questions about crank and piston on trx 3.3

[big jilm]

Hey guys, I'm tearing down both of my 3.3 mills to clean and reseal.. I got the first on ready to go. It just has to set up.. Then I will tighten everything down, I learned from my last job..

Question is on the newest mill. It has about 1 1/2 gallons on it and is in pretty good shape but once I tore it down I noticed that when you turn the flywheel there seems to be a little binding when the piston is at the top.. The piston is fine but Theres a little play in the crank shaft, Maybe 1/10th of a turn where the piston doesn't move... Thats also where the binding happens also. If I spin the fly wheel a little I can get it to bind where you can't move it. You have to go the other way then it will free...The everything turned smooth before I took it apart but I'm sure I haven't gotten anything in there...
I've never worked on the piston or crank and they both look like their in good shape.
Any ideas???? My wife has the camera but I can get some pics or a vid later If it will help... Thanks guys...

 

[surgemaster1970]

If there is play in the rod i would change it.You should also mic the crank to make sure the new rod will be tight enough when replaced and if not get a new crank also.Any play can change the engines attitude big time and make tuning harder by making port timing erratic,-theres also a chance at snapping the rod at WOT..Totally disassemble the engine and have a good look at the engine bearings they may be bad aswell...Good luck..

 

[big jilm]

This sucks!!!

 

[olds97_lss]

Look for actual play. At TDC or BDC, you will be able to move the crank a little bit without the piston moving hardly enough to be noticeable.

 

[big jilm]

Thanks guys... I played around for about another 10 minutes before I realized that the rod was catching on the housing because I had the backplate off and the back of the motor facing the ground. There was play but when I put the backplate on it was all snugg... I haven't worked on the mills much so I'm still learning...

Olds, the play at TDC was what I was refering to... Glad to hear its normal...

I got this mill back together and took both trucks for a spin.. This mill is screeming!!! I thought it was pretty fast before but now I'm pulling wheelies all day.. I'm running 250 degrees at factory settings whith this kind of power... Time to tune..

I've only had used trucks and both mills were in need of some work so I've never actualy seen a good running trx 3.3

 

[bobbyc1127]

man if your running 250 a stock settings you may wanna consider looking into some air leak issues. but there again i am hoping you mistyped that. no way a motor should be running at 250 with stock settings. or at least in my experience anyhow

 

[revo_rob_1984]

+1 on a hopeful misprint there
i don't have a TRX engine any more but my picco runs phenomenal at 255-260 and thats after i leaned it out about a turn and a half from stock (mayble a little more) but if your running that hot at stock settings you def, have some issues somewhere, start from the fuel tank and make ur way to the mill and see if there are any air leaks (fuel tank o ring, fuel lines, carb, backplate) i was having the same issue with my 3.3 when i had it and it ended up being my actual carb was cracked letting air in. . .so check that too

 

[hamz9561]

The Traxxas engines tend to run a little hotter than other brands, in my experience. With my 3.3, i remember running about that in the summer in South Texas on a stock tune.

 

[bobbyc1127]

i live in east tx and it is humid and hot there as well. but wow on a stock setting i never saw one that hot unless i had a head bolt loose or a fuel system issue.

 

[big jilm]

I have no leaks. I replaced everything.I was running alot hotter so I think sealing the mill has stoped that. I got this thing tuned up and it is screeming.. Running about 270. Pulling wheelies on comand, and that temp is ridding hard...
That 250 was after running wot for 5 minutes.. I'm in ga with 90 degrees out side and about 20% humidity..
I was hitting 300 before and it wasn't even running this well.. At 270 ,I think I have this one solved..

man if your running 250 a stock settings you may wanna consider looking into some air leak issues. but there again i am hoping you mistyped that. no way a motor should be running at 250 with stock settings. or at least in my experience anyhow

250 was max temp it reached. Was staying around 230.