spinner11

My Feedback: (37)

This may seem like a simple question but since this is my first truck I'm just starting to learn about it. I have set my slipper clutch at about 1/4 to 1/2 turn out. I just like the way it feels that way. The truck is really responsive but throttle management is critical especially on pavement or it will flip. It really rips on grass and dirt though. The problem is that at an idle the clutch is slightly engageing just enough to put load on the motor, making a prolonged idle very difficult because it eventually stahls. The truck even tries to roll a little. My other concern is that it is wearing on my clutch. I have adjusted the low end needle properley per the manual and the idle down as far as I can with out it stahling. I also replaced the glow plug.

What I'm wondering is if by setting the slipper so tight I have created a problem at idle. I thought that the slipper and clutch were seperate but I'm not sure now.

DaveG55

If you cannot lower the idle enough to keep the clutch from engaging then your still a bit off on your tuning. My LST will set and idle for several minutes w/o moving or dieing.

spinner11

My Feedback: (37)

Does it have anything to do with the slipper adjustment??

DaveG55

Nope, shouldn't. The clutch shoes on the crankshaft must engage the clutch bell to turn the spur gear. Only then does the slipper clutch come into play. The idle should be set to keep the shoes from engaging the clutch bell. That is directly related to engine speed and has nothing to do with the slipper.
Have you done a pinch test to see how the lsn is set?

spinner11

My Feedback: (37)

OK, thats what I thought about the clutch and slipper. I have a Dynamite .28 in this thing and I don't know if its the same as the stock .26 as far as needle adjustments go but it has a high needle, low needle, and idle screw. The manual says to pinch the fuel line just before the inlet nipple after the engine is at operating temperature. If it idles up just a touch then dies its perfect. Thats how I set the low needle. As far as the idle screw goes I have set it so that it idles as low as possible without stahling imediately.

Come to think of it I'm pretty sure that the idle screw just opens and closes the throttle and has nothing to do with the fuel/air mixture at idle. It's the low needle that needs to be tweaked for that and then the idle screw for the final adjustment. I don't think that the pinch methode is very accurate.

Here's what I'm gonna do and tell me what you think.
-Set the truck up on a block so the wheels will spin freely after its started.
-Adjust the low needle to the rich side while its running and checking throttle response
-then adjust idle screw to lower the RPM's after the low needle is good.



I think th

marzac2

I wouldn't put the car on blocks. The wheels shouldn't be allowed to rotate freely without load for long periods of time. Put the truck on the ground. Adjust the high speed needle first. Adjust the low speed needle next using the same method you used before. Than set the idle just as you have done before. If the problem still exists. I would open up the clutch area. You could have a clutch spring out or broken. Can you spin the clutch bell freely while it is still on the truck? If not, you definitely need to check the clutch. You might even have to shim the bell differently for that engine upgrade.

DaveG55

Of course the pinch test is not terrably accurate any more than saying you should run your engine at xxx degrees is accurate. Every nitro engine is different and tunes differently and constantly changes in response to ambiant conditions. It is, however, a good indication of how an engine is tuned and gives you an idea of what needs to be done. If your engine revs up right away and dies right away it is indicating a lean lsn condition. An engine with a properly tuned lsn will die between 4-5 seconds using the pinch test. It sounds like your engine is dieing before that so it is probably lean.
Do not tune the engine with the truck on blocks. You will not get an accurate tune and can damage the engine. It is important to run the truck for a short high speed run between each needle change during tuning to allow any accumlated fuel in the engine to clear out and give you a true indication of what changes your adjustments made.
If I were you I'd reset the needles to factory and retune the engine. Preset the idle screw so that there is a 1-2mm gap when looking down the carb throat - be sure that the throttle trim on the tx is turned all the way down before making any adjustments..
Tune the hsn 1/8 turn at a time for performance, smoke and sound. Run the truck on a short high speed run between adjustments. When you no longer notice any improvement in performance back the hsn off 1/4 turn. If you have a temp guage 240 - 260 is a good range to shoot for at final tuning. Now tune the lsn so that you get good response and power on take off. When you return from the high speed run the engine should return smoothly and evenly to idle. When you think you're right, do a pinch test. Remember you're shooting for 4-5 seconds but that's not exact. However, less than 3 seconds and more than 6 means you're still off a bit. Short means lean, long means rich. After you're satisfied with the lsn, recheck the performance of the hsn and, finally, adjust the idle screw if you need to.

There is an article out there that was written by the late Ron Paris of Paris Racing that explains tuning far better than I do and is worth finding and reading. If you do a search for "carb needle ballance" you should find it.
Hope this helps some.

spinner11

My Feedback: (37)

THanks for the advice guys...It's really appreciated. I should get a chance to work on it tomarrow and I'll update then to let you guys know what I found.

spinner11

My Feedback: (37)

Alright, I figured out what the problem was. After turning needles for about an hour today I took the clutch apart and found that 2 of the 3 clutch spings were broken. Pretty weird.