Stupid Tmaxx....Stupid TRX 3.3....

[olds97_lss]

Haha, no, not from round those parts at all

I've already done the pinch anyway, warmed the sleeve up in a bearing oven at work then quenched it in some nice clean oil. The piston is nicely nipped about 3-4mm from the top of the sleeve now.

Gonna give it a go at lunch time.

Let us know how it works! I wonder if since you used heat, that once it warms up a few times if it will retain the smaller size.

Always more than one way to skin a cat!

 

[Beddo]

Rebuilt yesterday and gave it another whirl, but still didnt work.
It really wants to, but it didnt quite fire up. I dont know why but I decided to fit my EZ start and see if that would help. The EZ spins faster than the Roto, so I guess I just wondered if it might help.

.....and it did

Ran it up at lunch time, did a couple of tanks break in for the new pinch and its running quite rich still, but it seems really good so far.

Damn am I chuffed

Thanks to all for your help. I'm not sure if I could actually pin-point the problem, probably lots of small issues, but at least now its a runner again.
Frustratingly, this engine was new about 8 weeks ago and has only had about 6 litres through it.....

 

[Metalhead Matt]

+1 for the ez start! I love it when you pull start guys get the screws put to ya! Pull start your mowers; start your rc's the ez way!

 

[Old2.5]

But more likely.......stupid Beddo.

Firstly, sorry for the long post, but I feel I need to explain everything I've tried.

OK, so I've got a TRX 3.3 which I have run about 3/4 gallon through of 25% (1st Monster Juice but now Byrons). The motor used to start no problem, warm or cold, and whilst I have had some tuning issues in the past, since I got these sorted it has been running like a gem.

Then the main bearing gave up, so that was changed for a new one. The sleeve and piston were checked and are in excellent condition. Compression and pinch seem good. I took the opportunity to completely seal the engine and it was at this point I noticed that one of the holes in the carb body where the larger blank plug fits had stripped its threads. I ordered a new carb body and at the weekend built and sealed the motor again.

Now I can't for the life of me get the thing to fire up.

I'm running a roto start and it just turns over, and over again, never really looking like its gonna fire. I've tried priming by plugging the exhaust and watching fuel go into the carb. I've gently blown into the pressure pipe and watched fuel go into the pipe. The only time the motor looks like it may start is if I drop a small amount of fuel into the mouth of the carb, then it will chug a bit, like its about to start, then continue just turning over.

I've done a pressure test on the fuel lines by plugging the fuel line at the end that goes into the carb, and blowing into the pressure line off the exhaust, so I'm confident that the fuel system is air tight, as is the engine.

I've tried new plugs, new batteries in the glow starter and in the roto start (I've even used a 7 cell pack to try get a bit more spped from the roto start)

I'm at my wits end as I simply dont know what to try next. I'm considering doing a home pinch job on the liner, but I'm sure that its OK since the compression feels pretty good.

I wondered if there wasn't enough fuel getting into the cylinder, the top of the piston never seems to be very wet when I take the plug out. Also if I try to start without the filter on (not something I would normally do obviously) there seems to be plenty of fuel coming back out of the mouth of the carb, especially if I plug the exhaust port, almost as if the fuel isnt getting into the motor?

Any ideas or suggested would be greatly appreciated. I've ordered an )S .18TZ, but it wont be here for a couple of weeks and I'm lost without my Maxx

put it back to factory settings which is 4 out on the hsn and 2 1/2 on the lsn

 

[olds97_lss]

The EZ spins faster than the Roto, so I guess I just wondered if it might help...
Frustratingly, this engine was new about 8 weeks ago and has only had about 6 litres through it.....

I had thought about mentioning that, but figured if it started with it in the past, not real sure why it wouldn't be fast enough to start it now. Listening to it crank over, it sounded really slow. The roto sounds fast, but the turns of the engine were very slow.

6 liters and you've already worn the pinch that bad? Have you been running it really hot?

 

[Beddo]

put it back to factory settings which is 4 out on the hsn and 2 1/2 on the lsn

Thanks, but you really need to read the whole thread, not just comment on the first post.

I had thought about mentioning that, but figured if it started with it in the past, not real sure why it wouldn't be fast enough to start it now. Listening to it crank over, it sounded really slow. The roto sounds fast, but the turns of the engine were very slow.

6 liters and you've already worn the pinch that bad? Have you been running it really hot?

It doesn't normally get above 210-220f, not knowingly anyway

Had another quick blast with it on my home from work last night........runs like a treat now, so well I managed to crack one of the grey chassis braces underneath :whhooo:

Still, at least now its a runner again I can splash some cash and get some alloy skids and braces