Nitro engine tuning Guide!!

[Jeremy]

This was writen by John Adams
of Rc hobbies Online::::: Really good guide here should help out allot ::::::

Source: http://www.rchobbies.org/cars_eng-tuning.htm

Nitro Engine Tuning
MAXIMIZE YOUR ENGINE'S POWER POTENTIAL
So now you can get your engine started on a regular basis, but you’re still struggling with the fine-tuning that will score you a win at the racetrack (or bragging rights at the parking lot). Properly tuning a nitro engine can make that difference without jeopardizing its health. It takes time to learn how to really tune your engine, however. There’s a certain “feel” to how your car drives and a certain sound you’ll come to know when your engine has been ideally tuned. Other cues that you feel and hear tell you what to adjust when your engine isn’t running properly. When it’s time to tune your engine, there’s no substitute for plain old experience. Reading about engine tuning is helpful, but you need to experiment with your engine to improve your tuning skills. The good news is that the following tips will help you avoid some of the pitfalls of fine-tuning and achieve tuning proficiency more quickly.
BASE-LINE MIXTURE SETTINGS
Engine manufacturers often include base-line settings for the mixture needles, so it’s wise to start with these. If this information is not provided, then you must arrive at needle settings that will get the engine started. A universal starting point is usually about 1 turn open (counterclockwise) on the low-speed needle and somewhere in the 2- to 3-turn range on the high-speed needle. This varies among engines, but it gets you started running, and then you can make the necessary corrections. After the initial startup, follow the proper break-in procedure, then worry about performance tuning!

The proper sequence for adjusting the mixture needles is hotly debated. When you start to fine-tune the engine, it’s generally best to start with the high-speed needle, then set the low-speed. First, however, get your engine running, and keep it running before you worry about race tuning.

During break-in, the engine typically idles a long time, so it’s best to adjust the low-speed setting first so the engine runs slightly rich (loading up every 30 seconds or so). It requires an occasional “blip” of the throttle to clear out any raw fuel that has accumulated in the engine. Once break-in is finished, then get the high-speed needle in the ballpark.

Place the car on the ground and accelerate smoothly to give the engine a chance to build some heat. With the high-speed needle in the proper range, the engine should be able to rev relatively well up to full speed once it has been running for a few minutes on the track or parking lot.

FINE-TUNING
A word of caution first: there’s a fine line between the perfect tune and a blown or damaged engine. Nitro-engine fuel also contains engine lubricant, so as you get close to dialing in the mixture to where there is just enough fuel to burn and deliver maximum power, you also are close to having just enough oil to keep the engine lubricated. Anyone with experience in tuning 2-stroke engines can tell you that they run best right before they seize or blow up. Our engines are a little tougher and more capable of taking some abuse than bigger 2-strokes, but there’s no sense in pushing the mixture settings so lean that you risk damage to the engine. I can’t say this too often: get the engine up to full running temperature by running the car exactly as you would on the track or parking lot. The high-speed needle setting depends on the type of driving you do. I’ll start with a racing setup.

HIGH-SPEED NEEDLE
Racers will tune the high-speed setting to get from point A to point B as quickly as possible. (Performance also depends on a proper low-speed needle setting, but for now, let’s concentrate on the high-speed setting.) The best place to race tune your engine is on the track where you run. I prefer to set the high-speed mixture so the car can leg out the track’s longest straight section in the shortest time. Estimate the time by “feel” and gut instinct, or use a stopwatch for more accuracy. The high-speed mixture should be set to maximize engine performance for that particular track configuration. A short, tight track may require a main mixture setting just a shade on the lean side to provide maximum power out of the corners. You needn’t be concerned about high-rpm performance because the track is too small for the engine to ever reach peak rpm. A long, high-speed track may require a slightly rich main-needle setting. If an engine constantly revs at the upper limits of the rpm range, the fuel mixture should be richened to ensure proper lubrication across the entire rpm range. This slightly rich setting might reduce bottom-end acceleration to a degree, but longer tracks require a slightly richer mixture setting to let the engine rev to its limits without running dry of fuel and oil.

Why is it important to tune the engine to the track? A mixture needle can only provide optimum performance within a relatively narrow rpm range. Anywhere below this hypothetical rpm range, the engine runs slightly rich; anywhere above, it gets progressively leaner. Until we have fuel injection that constantly optimizes fuel mixture throughout the rpm range, there needs to be a degree of compromise with the mixture settings. So, ideally, set the mixture to provide the most power in an rpm range that is best suited to the track on which you run.

WIDE-OPEN RUNNING
Running in parking lots, particularly larger ones with a lot of breathing room, requires unique mixture settings. It’s a common mistake to establish mixture settings for maximum punch—as though the car will be run within the confines of a tight racetrack—and then to go out and run at wide-open throttle (WOT) in a huge parking lot for 5 minutes. This type of running is incredibly unhealthy for an engine to begin with, and compounding the problem with an excessively lean main-needle setting is a recipe for disaster. If you still insist on torturing your engine, the high-speed mixture setting needs to be as much as 1/4 turn richer than typical to provide optimum fuel for the upper rpm range. The engine will be a little softer when accelerating from a standstill, but it’s the only way to ensure there is an adequate supply of fuel and oil when running at the upper end of the rpm range. The inherent danger is that this type of running taxes the connecting rod and other engine components to their limits, but having the proper mixture setting will at least delay the inevitable.

LOW-SPEED NEEDLE
The high-speed needle is dialed in, so now let’s properly set the low-speed needle. It’s important to set it last because it simply regulates the fuel that flows from the main needle at low throttle settings. Lean out the main needle, and you automatically lean the low-speed needle as well. For this reason, it’s wise to finish with the low-speed setting.

Again, it’s imperative for the engine to be at full operating temperature. There are many methods of testing the low-speed needle setting; one is to pinch the fuel line. When you pinch the fuel line, the engine rpm increase slightly. Keep pinching it, and the engine will eventually stall. If the engine rpm increase dramatically, it indicates that the low-speed setting may be too rich. Or, if the low-speed setting is already too lean, the engine rpm may not increase much at all, and the engine will stall rather quickly. It’s a somewhat crude method and doesn’t tell you what to expect from the engine on the track, but it will get you into the ballpark.

Another common way is the “see-how-long-it-will-idle” method. The low-speed needle adjustment affects how long the engine will idle. A too lean fuel mixture causes the engine to race and possibly stall, limiting the duration of a steady idle. A too rich low-speed-mixture setting causes the engine idle to steadily drop and eventually stall. The ideal setting allows the engine to hold a smooth, steady idle for 10 to 20 seconds (max), and then the engine rpm decrease steadily because the crankcase loads up with fuel. Why? There are no awards given for the longest-idling engine. If the engine is able to idle steadily for a longer time, then it may start to lean out and heat up during a race and make it difficult to drive the car and keep the engine running. The only flaw in this method is that it doesn’t tell you whether you have an artificially rich mixture to compensate for an idle speed that’s too high.

 

[Jeremy]

More

Nitro Engine Tuning
MAXIMIZE YOUR ENGINE'S POWER POTENTIAL
So now you can get your engine started on a regular basis, but you’re still struggling with the fine-tuning that will score you a win at the racetrack (or bragging rights at the parking lot). Properly tuning a nitro engine can make that difference without jeopardizing its health. It takes time to learn how to really tune your engine, however. There’s a certain “feel†to how your car drives and a certain sound you’ll come to know when your engine has been ideally tuned. Other cues that you feel and hear tell you what to adjust when your engine isn’t running properly. When it’s time to tune your engine, there’s no substitute for plain old experience. Reading about engine tuning is helpful, but you need to experiment with your engine to improve your tuning skills. The good news is that the following tips will help you avoid some of the pitfalls of fine-tuning and achieve tuning proficiency more quickly.
BASE-LINE MIXTURE SETTINGS
Engine manufacturers often include base-line settings for the mixture needles, so it’s wise to start with these. If this information is not provided, then you must arrive at needle settings that will get the engine started. A universal starting point is usually about 1 turn open (counterclockwise) on the low-speed needle and somewhere in the 2- to 3-turn range on the high-speed needle. This varies among engines, but it gets you started running, and then you can make the necessary corrections. After the initial startup, follow the proper break-in procedure, then worry about performance tuning!

The proper sequence for adjusting the mixture needles is hotly debated. When you start to fine-tune the engine, it’s generally best to start with the high-speed needle, then set the low-speed. First, however, get your engine running, and keep it running before you worry about race tuning.

During break-in, the engine typically idles a long time, so it’s best to adjust the low-speed setting first so the engine runs slightly rich (loading up every 30 seconds or so). It requires an occasional “blip†of the throttle to clear out any raw fuel that has accumulated in the engine. Once break-in is finished, then get the high-speed needle in the ballpark.

Place the car on the ground and accelerate smoothly to give the engine a chance to build some heat. With the high-speed needle in the proper range, the engine should be able to rev relatively well up to full speed once it has been running for a few minutes on the track or parking lot.

FINE-TUNING
A word of caution first: there’s a fine line between the perfect tune and a blown or damaged engine. Nitro-engine fuel also contains engine lubricant, so as you get close to dialing in the mixture to where there is just enough fuel to burn and deliver maximum power, you also are close to having just enough oil to keep the engine lubricated. Anyone with experience in tuning 2-stroke engines can tell you that they run best right before they seize or blow up. Our engines are a little tougher and more capable of taking some abuse than bigger 2-strokes, but there’s no sense in pushing the mixture settings so lean that you risk damage to the engine. I can’t say this too often: get the engine up to full running temperature by running the car exactly as you would on the track or parking lot. The high-speed needle setting depends on the type of driving you do. I’ll start with a racing setup.

HIGH-SPEED NEEDLE
Racers will tune the high-speed setting to get from point A to point B as quickly as possible. (Performance also depends on a proper low-speed needle setting, but for now, let’s concentrate on the high-speed setting.) The best place to race tune your engine is on the track where you run. I prefer to set the high-speed mixture so the car can leg out the track’s longest straight section in the shortest time. Estimate the time by “feel†and gut instinct, or use a stopwatch for more accuracy. The high-speed mixture should be set to maximize engine performance for that particular track configuration. A short, tight track may require a main mixture setting just a shade on the lean side to provide maximum power out of the corners. You needn’t be concerned about high-rpm performance because the track is too small for the engine to ever reach peak rpm. A long, high-speed track may require a slightly rich main-needle setting. If an engine constantly revs at the upper limits of the rpm range, the fuel mixture should be richened to ensure proper lubrication across the entire rpm range. This slightly rich setting might reduce bottom-end acceleration to a degree, but longer tracks require a slightly richer mixture setting to let the engine rev to its limits without running dry of fuel and oil.

Why is it important to tune the engine to the track? A mixture needle can only provide optimum performance within a relatively narrow rpm range. Anywhere below this hypothetical rpm range, the engine runs slightly rich; anywhere above, it gets progressively leaner. Until we have fuel injection that constantly optimizes fuel mixture throughout the rpm range, there needs to be a degree of compromise with the mixture settings. So, ideally, set the mixture to provide the most power in an rpm range that is best suited to the track on which you run.

WIDE-OPEN RUNNING
Running in parking lots, particularly larger ones with a lot of breathing room, requires unique mixture settings. It’s a common mistake to establish mixture settings for maximum punch—as though the car will be run within the confines of a tight racetrack—and then to go out and run at wide-open throttle (WOT) in a huge parking lot for 5 minutes. This type of running is incredibly unhealthy for an engine to begin with, and compounding the problem with an excessively lean main-needle setting is a recipe for disaster. If you still insist on torturing your engine, the high-speed mixture setting needs to be as much as 1/4 turn richer than typical to provide optimum fuel for the upper rpm range. The engine will be a little softer when accelerating from a standstill, but it’s the only way to ensure there is an adequate supply of fuel and oil when running at the upper end of the rpm range. The inherent danger is that this type of running taxes the connecting rod and other engine components to their limits, but having the proper mixture setting will at least delay the inevitable.

LOW-SPEED NEEDLE
The high-speed needle is dialed in, so now let’s properly set the low-speed needle. It’s important to set it last because it simply regulates the fuel that flows from the main needle at low throttle settings. Lean out the main needle, and you automatically lean the low-speed needle as well. For this reason, it’s wise to finish with the low-speed setting.

Again, it’s imperative for the engine to be at full operating temperature. There are many methods of testing the low-speed needle setting; one is to pinch the fuel line. When you pinch the fuel line, the engine rpm increase slightly. Keep pinching it, and the engine will eventually stall. If the engine rpm increase dramatically, it indicates that the low-speed setting may be too rich. Or, if the low-speed setting is already too lean, the engine rpm may not increase much at all, and the engine will stall rather quickly. It’s a somewhat crude method and doesn’t tell you what to expect from the engine on the track, but it will get you into the ballpark.

Another common way is the “see-how-long-it-will-idle†method. The low-speed needle adjustment affects how long the engine will idle. A too lean fuel mixture causes the engine to race and possibly stall, limiting the duration of a steady idle. A too rich low-speed-mixture setting causes the engine idle to steadily drop and eventually stall. The ideal setting allows the engine to hold a smooth, steady idle for 10 to 20 seconds (max), and then the engine rpm decrease steadily because the crankcase loads up with fuel. Why? There are no awards given for the longest-idling engine. If the engine is able to idle steadily for a longer time, then it may start to lean out and heat up during a race and make it difficult to drive the car and keep the engine running. The only flaw in this method is that it doesn’t tell you whether you have an artificially rich mixture to compensate for an idle speed that’s too high.

 

[Jeremy]

By STEVE POND!!!!!!

This Info is by STVE POND!!!!!!! Allot of good info here..I have read this many times !!!!


Airtight is Right
In order for an engine to idle, transition and tune consistently it must be airtight- airtight meaning that no air can enter the engine except through the carburetor intake. Surprisingly, even brand new out-of-the-box high-end engines can have air leaks and until these leaks are found and eliminated, the engine won't run consistently and cannot be precisely tuned. The good news is, several years ago I figured out an easy way to check for and fix air leaks. You'll need the following:
• A small glass of soapy water
• A small brush
• About a foot of fuel tubing

Step 1. Be sure that the high-speed needle is open at least two turns out and the throttle is at fully open.
Step 2. Install one end of the fuel tubing on the carburetor nipple. You're going to be blowing into the other end of the tubing to pressurize the engine crankcase.
Step 3. Place your thumb over the carburetor intake to prevent air from escaping, then blow into the fuel tubing while brushing soapy water around the base of the carburetor, on both sides of the pinch bolt, around the fuel fittings, at the high and low speed needle valves, around the front bearing and even around the back plate.

If any bubbling occurs you've got an air leak. But don't be alarmed. Fixing the leak is easy and your engine will run remarkably better and more consistently when you've eliminated these leaks.


The Fix


Brushing soapy water around all possible air leak points while pressurizing the case will easily identify air leaks.
The most common air leaks seem to occur around the pinch bolt. Applying a dab of RTV (or silicon) over both exposed sides of the pinch bolt will fix this type of leak. RTV is also great for sealing any leaks around the base of the carburetor. Simply remove the carburetor and run a small amount of RTV around the base of the carb where the leak occurred. Reinstall the carburetor and allow the RTV to ooze out between the crankcase and the carb body. For leaks around the high-speed needle valve fittings, usually retightening the high-speed needle assembly will take care of these. Leaks directly at the high speed or low speed needle usually means there's a damaged O-ring that must be replaced. Many racers don't realize that the front bearing can leak air. That's why nearly every high-end engine uses a rubber sealed front ball bearing to not only keep out dirt, but also air. If your front bearing leaks air, it's time for a bearing replacement.

This simple leak check can easily be done even when the engine is installed in a car. After you've done this test on several engines you'll be surprised of two things: first, how often unwanted air leaks occur and second, how much better your engine runs, idles and tunes when it's airtight. To run right it must be airtight!

Airtight Fuel system
The Fuel system must also be airtight. If the fuel tank, tank lid, fuel lines or filter has a leak then the same kind of tuning issues as described above will occur. While you can check the fuel system by using the same method of brushing soapy water onto the suspected offending area while blowing into the tank, I generally find it better to simply remove the tank from the car and submerse it in a sink of water while blowing into the vent line and plugging the fuel line. If bubbles are present you've got a leak.

An engine at full throttle produces about 6 to 8 psi in the vent line and conversely in the tank. By blowing really hard you're also able to produce about 6 to 8 psi for a couple of seconds. If you're able to blow hard enough to cause the tank lid to open slightly and leak, it's time to replace the tank lid spring or bend more preload in the spring. The entire system (fuel tank, fuel filters, fuel lines, tank fittings, etc.) must be airtight to achieve consistent repeatable performance. I always that my fuel system is airtight when it's new but also recheck it every time I rebuild a car after a race. It easy insurance plus soapy water is a good way to thoroughly clean the tank. Just be sure it's totally dry before using it by flushing out any water left in the tank with fuel before installing it in you car.

 

[Jeremy]

More!!!!

Tuning in a Pinch

The pinch test.
Many racers find it difficult to properly tune the low speed needle. We've developed a method that makes it easy, even for beginners, to adjust the low speed needle to within 5% of peak performance and it's done right on the bench. We call it the pinch test and here's how it works.

Step 1. Start your engine and warm it up for about 30 seconds by revving the engine from idle to mid-throttle while holding the wheels off the ground.

Step 2. Allow the engine to idle for 10 seconds. If the low speed needle tuning is so far off that it won't idle, simply bump the idle position higher until the engine will reliably run at a higher idle.

Step 3. With the engine at idle, pinch and hold the fuel line near the carburetor, cutting off the fuel flow and carefully listen to the engine rpm.

If the low speed needle is set correctly, the engine should increase rpm only slightly and then die.

If the engine increases several hundred rpm before dying, then the low speed needle is too rich and needs to be turned in.

If the rpm doesn't increase at all and the engine simply dies, the low speed needle is set too lean and should be richened or turned out.

After doing this a few times you'll get the hang of it, and tuning the low speed needle will become easy. The only way to get that last 5% performance on the low speed tune is through careful track testing. By evaluating the engine as it accelerates from a dead stop or out of slow corners during actual race conditions is the only way to get those last few percent of power from your engine. Variables like the clutch setting, gearing, traction, atmospheric conditions and even the car's weight will have an effect on this last 5% of tuning performance, and the optimum setting can only be reached by careful on-track tuning.

Fine Tuning in a Punch
On high traction tracks instant throttle response and acceleration are the keys to being competitive. To get that last 5% of performance thru tuning, many top drivers and engine tuners use the punch test. Here's how it works.

With the high speed needle properly set and the low speed needle set per the pinch test above, run several laps at race pace to bring the engine up to temperature. Now stop the car at the beginning of the main straight and allow it to idle while you count to 15. At the count of 15, hit the throttle instantly full punch while carefully listening to the engine and note the rate of acceleration. If you did a good job with the pinch test above and the high-speed needle is properly set as described below, the car should rocket off the line with a powerful, crisp consistent engine sound. The trick here is to tune the low speed needle for even greater acceleration and an even crisper throttle response. Do this punch test several times until your very familiar with the acceleration rate (it helps to judge the amount of wheel spin) and the sound of the engine as it accelerates to full throttle. Now lean the low speed needle 1 hour (or 1/12th of a turn) and do the punch test again. Is the engine's acceleration rate and the crisp consistent sound better than in the previous test? Remember judging the wheel spin (the amount the wheels slip during heavy acceleration) is a good way to compare. If it's better or there's no change, lean the low speed needle 1 hour more and try the punch test again. At some point the engine will lean bog (hesitate) off the line during acceleration indicating that you've gone too far.

When you finally find this point through repeated punch tests then leaning the low speed needle one hour each time, richen the low speed needle 2 hours. This will be your engines peak setting giving maximum acceleration and throttle response for the specific conditions of the day. Just remember if you change anything, like gear ratios, clutch settings, exhaust systems, fuel, glow plugs and even changing atmospheric conditions like temperature and barometric will cause this optimum setting to change. Repeat the punch test often and especially just before a heat race to ensure maximum performance during the existing conditions.


The Dreaded Full Tank Lean Bog
If you've done much gas racing, you've probably encountered the dreaded lean bog that occurs right after a pit stop with a full tank of fuel. Right after the tank is filled, for about the next 3 or 4 laps the engine sags (lean bogs) when accelerating off of tight right-hand corners. On most tracks this happens when accelerating onto the straight. Seemingly, the lean bog magically goes away after a few laps but sure enough, after the next pit stop, it frustratingly returns-slowing lap times for several laps once again.
The key to eliminating full tank lean bogs is pressure tube position or adding a pressure reservoir as shown.
To solve this frustrating issue, it's important to understand what's causing it.
Here's the scoop. As the throttle is released entering a turn, the pressure in the tank is now greater that the reduced pressure in the pipe. When the tank is full, some of the fuel sloshes up into the pressure line. The centrifugal forces encountered in a right hand turn further pulls the fuel into the pressure line, causing reduced pressure in the tank. When the throttle is cracked open to accelerate, the engine goes lean because of this reduced tank pressure and hence the dreaded lean bog occurs. The reason it only lasts for a couple of laps is first, as the fuel level goes down in the tank it's less likely to slosh as much into the pressure line and second, as the fuel level goes down there is a larger open space in the tank that's pressurized, maintaining adequate pressure long enough to prevent the low pressure lean bog problem. (If your exhaust system is mounted on the left side, as with some of the latest monster trucks, then this phenomenon will occur in left hand turns.)

The Fix

Keep the fuel out of the pressure line! That's sometimes easier said than done. We've had the most success by rerouting the pressure line so that as it come off the pressure nipple, the tubing goes to the right side of the fuel tank, then makes a loop on the right side of the tank. This prevents the centrifugal force of a right hand turn from filling the pressure tube. We've also had good success by adding one of the big reservoirs (they look like a big aluminum fuel filter and are available from Mugen or OFNA) in the pressure line. Many manufacturers, like Mugen and Serpent, recognize this problem and are making special pressure pickups and tank lids with large open volumes in the lid itself. You may have noted that many top drivers' cars have several loops of fuel tubing wrapped in their cars and wondered what was the purpose. Now you know. The key to fixing this issue is to experiment with pressure tube routing and, if necessary, installing a pressure reservoir in the pressure line.


Vapor Lock

Compressed CO2 sprayed directly onto the carburetor is a great way to prevent vapor lock during long main flame-outs.
If you've ever had your engine flame out after a reasonably long run and then found it nearly impossible to re-start, you may have experienced vapor lock. Vapor lock occurs most often in .12- and .15-size engines, especially when they're enclosed in a body with a 1/10-scale gas sedan or stadium truck. Vapor lock normally occurs after the engine is shut off. Heat from the head and combustion chamber transfers through the crankcase, heating the carburetor to the point that the fuel that reaches the carburetor through the fuel line boils off. This makes it impossible to start the engine because it's starved for fuel. The only way to get the engine to run is to cool the carburetor below the fuel's boiling point. If you're sport driving, you can simply wait 5 minutes for the carb to cool on it's own and then restart. If you're in the middle of an important long main, here are some creative ways racers have (including at the world championship level) cooled their carburetors preventing vapor lock:

1. A bottle of compressed CO2 (or air like those that can be purchased to operate airbrushes) with a nozzle attached, allowing cold CO2 to be directed over the carburetor even when the body is in place. We've seen several top-level race teams use this CO2 method anytime the engine flames out to prevent the possibility of a vapor lock.

2. By pulling the air filter and simply dumping fuel from the fuel bottle over the carburetor, usually bringing the temperature back to a tolerable level within a minute. Just be sure to avoid getting fuel on the brakes, radio equipment or tires or you could be in for a bad race day!

 

[Jeremy]

http://www.teamassociated.com/basicshub/troubleshooting/index.htm

another good guide easy to read also!!!!!!!!!

 

[DOOBEEWHA]

a...YEah!! ,,,No doubt, SJ.. Great postings.

 

[puckamahow racing]

well worth the read ty!

 

[tonikeys]

This thread has certainly been the most informative thread i've read since I got my savage.

Thanks

 

[Shaun]

wow u guys have done it again! thats alot of good info, thanks guys!:10:

 

[Jeremy]

Your welcome this is what this site is for

 

[HPISF-POLICE]

Here is a couple vid's I found thought they might help
(Part 1)

(Part 2)

 

[Crash]

Jester thanks, this is an incredible source of info into the our mighty little engines

This is a must read and should be a stickyyyyyyyyyyyyyyyyy!

 

[scooter4478]

awesome info rep points awarded!!!!!!!!!!!!!!

 

[faisalbasha]

my k4.6 engine is making a constant popping sound when I'm in full speed. I'm not sure what is happening with the engine. anyone have any idea what that is??

 

[Jeremy]

Probably too lean .. Do you have a good somke trail ?

 

[faisalbasha]

ya theres a lot of smoke..

 

[bwl2828]

love it now this is why i stay here u guys just know sooo much thanks for the post man

bwl2828

 

[Grumpy1822]

I bought that book and the dvd. The book is great. Lots of info. The dvd isnt that great. Not near as helpful as the book.

 

[fouteros]

This thread has certainly been the most informative thread i've read PERFECT

 

[schwanklv]

this is an awesome thread so many helpful tips...

 

[tripledigits]

now that was simple. thanks. My little .26 should be running tip top in know time. thanks again.

 

[rikkidy]

now that was simple. thanks. My little .26 should be running tip top in know time. thanks again.

Thanx for the info guys it is excellent of you to share your knowledge. I could not get either link to work tho.
Keep it up, there are a lot of peeps out here that appreciate your work and help.

 

[mikelh]

k4.6 middle speed needle adjustment.
With HSN set just barely lean enough to allow engine to clear out and achieve top end RPM's my engine wouldn't want to idle down properly after WOT. By making small adjustments CCW (richening) the MSN I was able to get the engine to transition from correct HSN setting to LSN setting. Afterwords I needed to lean the LSN slightly and was able to close idle gap slightly as well.
I haven't seen this information anywhere and hope my experience from today can help someone who might encounter a similar situation in the future.

 

[olds97_lss]

Here's a lengthy tuning guide with heat cycle instructions from an engine modifier from back in the day, Ron Paris:
Ron Paris Tuning and break-in Guide

I downloaded a version of this many years ago and it was formatted really badly. I spent an hour making it a bit more legible. The "Break In" section starts on page 9.

 

[Nighthawk]

This was writen by John Adams
of Rc hobbies Online::::: Really good guide here should help out allot ::::::

Source: http://www.rchobbies.org/cars_eng-tuning.htm

Nitro Engine Tuning
MAXIMIZE YOUR ENGINE'S POWER POTENTIAL
So now you can get your engine started on a regular basis, but you’re still struggling with the fine-tuning that will score you a win at the racetrack (or bragging rights at the parking lot). Properly tuning a nitro engine can make that difference without jeopardizing its health. It takes time to learn how to really tune your engine, however. There’s a certain “feel” to how your car drives and a certain sound you’ll come to know when your engine has been ideally tuned. Other cues that you feel and hear tell you what to adjust when your engine isn’t running properly. When it’s time to tune your engine, there’s no substitute for plain old experience. Reading about engine tuning is helpful, but you need to experiment with your engine to improve your tuning skills. The good news is that the following tips will help you avoid some of the pitfalls of fine-tuning and achieve tuning proficiency more quickly.
BASE-LINE MIXTURE SETTINGS
Engine manufacturers often include base-line settings for the mixture needles, so it’s wise to start with these. If this information is not provided, then you must arrive at needle settings that will get the engine started. A universal starting point is usually about 1 turn open (counterclockwise) on the low-speed needle and somewhere in the 2- to 3-turn range on the high-speed needle. This varies among engines, but it gets you started running, and then you can make the necessary corrections. After the initial startup, follow the proper break-in procedure, then worry about performance tuning!

The proper sequence for adjusting the mixture needles is hotly debated. When you start to fine-tune the engine, it’s generally best to start with the high-speed needle, then set the low-speed. First, however, get your engine running, and keep it running before you worry about race tuning.

During break-in, the engine typically idles a long time, so it’s best to adjust the low-speed setting first so the engine runs slightly rich (loading up every 30 seconds or so). It requires an occasional “blip” of the throttle to clear out any raw fuel that has accumulated in the engine. Once break-in is finished, then get the high-speed needle in the ballpark.

Place the car on the ground and accelerate smoothly to give the engine a chance to build some heat. With the high-speed needle in the proper range, the engine should be able to rev relatively well up to full speed once it has been running for a few minutes on the track or parking lot.

FINE-TUNING
A word of caution first: there’s a fine line between the perfect tune and a blown or damaged engine. Nitro-engine fuel also contains engine lubricant, so as you get close to dialing in the mixture to where there is just enough fuel to burn and deliver maximum power, you also are close to having just enough oil to keep the engine lubricated. Anyone with experience in tuning 2-stroke engines can tell you that they run best right before they seize or blow up. Our engines are a little tougher and more capable of taking some abuse than bigger 2-strokes, but there’s no sense in pushing the mixture settings so lean that you risk damage to the engine. I can’t say this too often: get the engine up to full running temperature by running the car exactly as you would on the track or parking lot. The high-speed needle setting depends on the type of driving you do. I’ll start with a racing setup.

HIGH-SPEED NEEDLE
Racers will tune the high-speed setting to get from point A to point B as quickly as possible. (Performance also depends on a proper low-speed needle setting, but for now, let’s concentrate on the high-speed setting.) The best place to race tune your engine is on the track where you run. I prefer to set the high-speed mixture so the car can leg out the track’s longest straight section in the shortest time. Estimate the time by “feel” and gut instinct, or use a stopwatch for more accuracy. The high-speed mixture should be set to maximize engine performance for that particular track configuration. A short, tight track may require a main mixture setting just a shade on the lean side to provide maximum power out of the corners. You needn’t be concerned about high-rpm performance because the track is too small for the engine to ever reach peak rpm. A long, high-speed track may require a slightly rich main-needle setting. If an engine constantly revs at the upper limits of the rpm range, the fuel mixture should be richened to ensure proper lubrication across the entire rpm range. This slightly rich setting might reduce bottom-end acceleration to a degree, but longer tracks require a slightly richer mixture setting to let the engine rev to its limits without running dry of fuel and oil.

Why is it important to tune the engine to the track? A mixture needle can only provide optimum performance within a relatively narrow rpm range. Anywhere below this hypothetical rpm range, the engine runs slightly rich; anywhere above, it gets progressively leaner. Until we have fuel injection that constantly optimizes fuel mixture throughout the rpm range, there needs to be a degree of compromise with the mixture settings. So, ideally, set the mixture to provide the most power in an rpm range that is best suited to the track on which you run.

WIDE-OPEN RUNNING
Running in parking lots, particularly larger ones with a lot of breathing room, requires unique mixture settings. It’s a common mistake to establish mixture settings for maximum punch—as though the car will be run within the confines of a tight racetrack—and then to go out and run at wide-open throttle (WOT) in a huge parking lot for 5 minutes. This type of running is incredibly unhealthy for an engine to begin with, and compounding the problem with an excessively lean main-needle setting is a recipe for disaster. If you still insist on torturing your engine, the high-speed mixture setting needs to be as much as 1/4 turn richer than typical to provide optimum fuel for the upper rpm range. The engine will be a little softer when accelerating from a standstill, but it’s the only way to ensure there is an adequate supply of fuel and oil when running at the upper end of the rpm range. The inherent danger is that this type of running taxes the connecting rod and other engine components to their limits, but having the proper mixture setting will at least delay the inevitable.

LOW-SPEED NEEDLE
The high-speed needle is dialed in, so now let’s properly set the low-speed needle. It’s important to set it last because it simply regulates the fuel that flows from the main needle at low throttle settings. Lean out the main needle, and you automatically lean the low-speed needle as well. For this reason, it’s wise to finish with the low-speed setting.

Again, it’s imperative for the engine to be at full operating temperature. There are many methods of testing the low-speed needle setting; one is to pinch the fuel line. When you pinch the fuel line, the engine rpm increase slightly. Keep pinching it, and the engine will eventually stall. If the engine rpm increase dramatically, it indicates that the low-speed setting may be too rich. Or, if the low-speed setting is already too lean, the engine rpm may not increase much at all, and the engine will stall rather quickly. It’s a somewhat crude method and doesn’t tell you what to expect from the engine on the track, but it will get you into the ballpark.

Another common way is the “see-how-long-it-will-idle” method. The low-speed needle adjustment affects how long the engine will idle. A too lean fuel mixture causes the engine to race and possibly stall, limiting the duration of a steady idle. A too rich low-speed-mixture setting causes the engine idle to steadily drop and eventually stall. The ideal setting allows the engine to hold a smooth, steady idle for 10 to 20 seconds (max), and then the engine rpm decrease steadily because the crankcase loads up with fuel. Why? There are no awards given for the longest-idling engine. If the engine is able to idle steadily for a longer time, then it may start to lean out and heat up during a race and make it difficult to drive the car and keep the engine running. The only flaw in this method is that it doesn’t tell you whether you have an artificially rich mixture to compensate for an idle speed that’s too high.

First of all I just want to say I am new to nitro engines so please be gentle lol. I am trying to get the right tune on my savage x. At first I thought I was doing it right.. I used a feeler gauge to set a .50 idle gap then with high and low needle set to factory I began. I first started with the HSN 1/8 at a time till I got a nice speed with still a good amount of smoke.. I think in total was about 1 and 1/4 turns. But I noticed that the car would bog on acceleration, from what I've learnt this means the LSN is too rich.. I adjusted this 1/8 at a time till I got her to accelerate at full throttle. But I now have an issue that the car bogs after a prolonged idleing time (2mins). It soon rights itself after a bit of running. I tried to tune it out, but I ended up ruining the nice tune I had, didn't fix the problem and the car sounds like it peaks and troughs on idle now. Any advice you can give would be received very gratefully, thank you.