Need help with Traxxas Revo 3.3 tuning
 

Ok, im fairly new to rc and nitro and made a trade for a used revo 3.3. Ran good, started to make some upgrades and now it won't run. I've been workin on it for 3 weeks now and nothing helps. It idles very high. high enough to spin the spur gear. Reset the needles to factory and it wont stay running at all, starts and dies immediately. If I richen the LSN it will idle. Sometimes it will idle for a little bit then it sounds like its flooding out and dying. When I have it warmed up if i throttle it more than about 1/4 it will die immediately. If i ease on the throttle it smokes like crazy and starts to stumble and dies. I thought it was an air leak so I changed the block and bearings, tried 2 different carbs, 2 gas tanks, 2 exhaust pipes. It is also dripping oil out of the ez start. Changed backplate and havent run it yet so I don't know if that helped. To me it seems to be running really rich, but if I lean it out it doesnt run at all. Please help!
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RE: Need help with Traxxas Revo 3.3 tuning
 

have you tried a new glow plug?

RE: Need help with Traxxas Revo 3.3 tuning
 

thats what i was thinking, same thing happened to me.

RE: Need help with Traxxas Revo 3.3 tuning
 

I have tried a couple glow plugs. They are not traxxas but are the O'Donnell plugs for my engine. I did notice it will stay running as long as the glow plug ignitor is on itwithout stalling out. Has anyone had problems with these glow plugs?

RE: Need help with Traxxas Revo 3.3 tuning
 

what condition is the engine? is it sealed? have you checked carb?

RE: Need help with Traxxas Revo 3.3 tuning
 

the engine is in pretty good shape. has just over a gallon of fuel through it. I did a leak test and the front bearing behind the flywheel seemed to be leaking excessively so thats why I bought the new block with bearings. Everything seems pretty tight now. I'm probably gonna go get a new traxxas glow plug to see if that helps, but I would think once the engine is warm and the glow plug ignitor is off it wouldnt matter. Traxxas said that it could be low compression, but it hasnt been run that much and I can barely get it to turn over by hand, feels pretty tight still.</p>

RE: Need help with Traxxas Revo 3.3 tuning
 

I dont know man, im stumped. Try the new glow plug and lets us know.

RE: Need help with Traxxas Revo 3.3 tuning
 

make sure you clear the engine before removing the ignitor. give it full throttle slowly to burn any excessive fuel in the bottom end.

RE: Need help with Traxxas Revo 3.3 tuning
 

New glow plug did no good.  Took it to the LHS today.  Its running better, but still not right.  Idles and will drive slow.  The minute you go wide open throttle it dies.  They tinkered with it a little and now you can slowly bring it up to wot, smokes and is sluggish, but once ur up there if you let off and wot again it sounds good, but then you can hear it load up with fuel and die.  Also there is fuel dripping off the ez start.  Anyone know why it would be getting so much fuel at idle?  Pretty sure its not the carb tune.  It also had good compression.  Don't know exactly, but he said it was over 60 psi. 

RE: Need help with Traxxas Revo 3.3 tuning
 

New glow plug did no good.  Took it to the LHS today.  Its running better, but still not right.  Idles and will drive slow.  The minute you go wide open throttle it dies.  They tinkered with it a little and now you can slowly bring it up to wot, smokes and is sluggish, but once ur up there if you let off and wot again it sounds good, but then you can hear it load up with fuel and die.  Also there is fuel dripping off the ez start.  Anyone know why it would be getting so much fuel at idle?  Pretty sure its not the carb tune.  It also had good compression.  Don't know exactly, but he said it was over 60 psi. could it b a leaky backplate?

RE: Need help with Traxxas Revo 3.3 tuning
 

Probaly the back plate. I'm just saying lol hope you get it fixed.

RE: Need help with Traxxas Revo 3.3 tuning
 

New backplate.  same problem.  Wont stay running.  Will start then you can hear the engine flooding out.  Still runs ok with the glow plug ignitor on.  But you take it off and sounds terrible and dies.  Anybody?

RE: Need help with Traxxas Revo 3.3 tuning
 

have you tried a different carb?

RE: Need help with Traxxas Revo 3.3 tuning
 

I've tried 3 different carbs all with the same results. Figured out the exhaust pipe was cracked and that was causing the oil on the ez start. I assume it is something with the engine itself. As far as I know theres not much that I could reassemble wrong inside the engine. Never took the rod off the piston. Cutout on the piston skirt goes toward the intake, right? I had it at idle and was watching a bubble in the fuel line. As soon as it started to sound rough the bubble started to go back toward the tank. That doesn't make sense to me. Should there be a check valve in the fuel tank somewhere? Just stabbin in the dark, but I really don't want to send it to traxxas.

RE: Need help with Traxxas Revo 3.3 tuning
 

how good is compression?
heres a good video

[youtube]http://www.youtube.com/watch?v=AP_7hBvyWbs&feature=related[/youtube]

RE: Need help with Traxxas Revo 3.3 tuning
 

thanks for the help so far. LHS checked compression and he said it was above 60 psi and that was pretty good. A friend of mine said maybe it was building too much pressure in the tank forcing too much fuel through. I'm bangin my head against a wall. I have watched several videos on rebuilding. I've had it apart about a dozen times now and nothing seems to help. I give up.

RE: Need help with Traxxas Revo 3.3 tuning
 

You have your needles set right?

RE: Need help with Traxxas Revo 3.3 tuning
 

yeah. I reset it to 4 turns out on the hsn and flush with the barrel on the lsn. Tried tuning with it running but nothing seems to help.

RE: Need help with Traxxas Revo 3.3 tuning
 

do you have a video?

RE: Need help with Traxxas Revo 3.3 tuning
 

Well took it back in to the LHS and left it overnight.  Went back the next day and they had it running.  He said he leak tested everything and all was sealed.  Brand new glow plug was shot also one way bearing was shot.  Cost me $47 but its running much better.  He also said the LSN was acting funny.  said if he just touched it, it would mess the idle up.  I wish it would have been something more definitive, but Im just glad its running now.  Thanks for all your help everyone.

RE: Need help with Traxxas Revo 3.3 tuning
 

glad ya got it running, I had a truck do that once. New glow plug and it ran like a champ

RE: Need help with Traxxas Revo 3.3 tuning
 

If you know the idle is set right, you can turn the lsn in 1/16 turn at a time til it idles. You're looking for that nice clean sounding idle for at least5 seconds, then when you nail the throttle it should take off nicely, without loading up.
If you think it might be the hsn then you can turn that out until it runs noticeably richer and then lean it little by little from there.