ok some what new to nitro

[bbl993]

Got a traxxas revo. I retuned the carb cause the previous owner had it all out of whack. Runs for about 10 mins then cuts out. Let it sit for about 15mins it starts up again and will run for another 10mins then cuts outs again. I re-set the carb back to factory. It runs a little better but same cut out issue. Any Suggestions? The old glow plug I pulled out was white so the previous owner was running it pretty lean. Got a new one and still up agaisnt a wall with it cutting out. Any ideas?

 

[RC Addict]

When it cuts out and dies you say you let it sit for 15 minutes and it starts up again. Do you refill the fuel tank before starting it again, or restart it without topping the tank off?

 

[bbl993]

no i dont refill the fuel. I just let it sit. I think its low on compression. seems once it gets hot thats all its got. spun the engine over by engine it hits the top stroke i can move it past it with me finger.

 

[stevecz28]

your revo did the same thing mine did...my engine was tired. when you start it up itll run about 10 minutes or until the engine is warm, then die because the sleeve expands soo much that there is no compression/pinch left in it. you let it sit for abut 15 minutes or enough to cool down and shrink back to normal size and start over...time to replace that engine or find a good hobby shop and try repinching your sleeve for about 20 bucks

 

[RC Addict]

+1. Just wanted to rule out a fuel tank pickup leak before proclaiming your mill toast.

 

[traxxas t-maxx]

Yup your engine is gone I did the erp through traxxas and I liked it they send you a brand new engine of coarse at your cost and you get a new one back in about two weeks.

 

[bbl993]

so I'm pretty at building Gas engines for cars there shouldn't be much at taking one of these apart and getting a sleeve and piston for it. I did already take the engine apart (good tip with the cable tie to get the sleeve out via the exhaust port ) The crankcase has a rusty brown color to it. Am I safe using brake parts cleaner for the lower end to clean it out or just soak it in some nitro fuel? Theres not a lot of play with the crank seemse pretty tight. I for the life of me can't get the 8mm nut off for the flywheel so I didnt bother. So clean it with some nitro fuel or find somthing else. I dont want to wash the bearings out. Hobby store opens at noon. I plan on having this running this afternoon. .


Being how easy this was to take apart an reccomendations on nice connecting rod or just reuse the old one. It seems good, no scoring on the bearing race. And the crank lobe for the bottom of the connecting rod seems good.

when i go back together whats the orentation with the piston and the sleeve. I notice there is a notch in the bottom of the piston...

 

[ThunderTiger]

i would say replace the conrod aswell, that way, you know its good, plus, it wont break on you.

I'm about to replace a piston and liner, so i will also be ordering a new conrod as a matter of course.

As to which way round the conrod goes, check the way its fitted to the piston b4 you remove it. The piston has a cut-out (The "Notch" u mention) at the bottom which clears the crank counter balance. This cut out faces towards the front end of the engine when fitted. Therefore, if the conrod has a "Groove" and/or "Lube" hole on it, and they face away from the notch (towards the rear end of the engine), that is how it must be re-fitted.

 

[Dandyfunk]

Hey bbl993, I once had the same problem with a Traxxas T-Max It turned out that I did not break the motor in correctly causing the problem. If the rig runs for 10 mins then dies it will be becouse it has overheated...most likely due to in-proper break in. Sometimes it is possible to go back and re-do the break in proceedure. Follow the directions provided by Traxxas to the letter!! You might get lucky...if not the motor will need a rebuild (do we still do that these days??) or replacement. It is possible there may be anouther cause but I can't think of one....You can check my overheating theroy by temp checking the head when the rig dies and compare your temp to another Revo that has been running for the same time. Sorry I dont know what the head temp should be on a Revo. Hope this helps Dandyfunk.

 

[bbl993]

ok well I was thinking the burn in didnt take so i put it all back together (hobby store around here didnt have a piston and sleeve). Tried it again. I can't even get it to start on the bench. Wifes a nurse so she had some large syringes around and I got one that fit the extra piece of fuel line I had laying around. Just to see if it would start I lightly clamped it in vice and spun it over with me easy start pig tail i had laying around. Is it possible to have the back plate on too tight? I had trouble spinning it on the flywheel with my fingers. But a few pulls with the easy start it loosened up a bit. It wants to start I keep enough pressure on the syringe to see fuel going in. After about five mins the easy start isnt so easy...

Had I got it to start I know enough not to rev it just to let it idle so I can dial the cold start in. But no dice. I think I'm going to wait a couple weeks and bite the bullet and do the ERP...

 

[bbl993]

ok my wife let me get a new 2.5r engine from the LHS. 90 bucks plus tax got me a new traxxas 2.5r. WOOT! Even came with a free pull start. I think I'm going to ditch that ez start crap. I'll let you all know how this thing works. Thanks for your help!!!

 

[MotoGod]

Traxxas has a nice Engine Replacement plan as well. I believe with a 2.5 and $80 you can get a brand new 3.3