putting my first rebuild back together?

[MajesticTRX250R]

any tips or suggestions?

i have the cylinder, piston, rings, gaskets, intake boot, ect sitting in front of me about to throw it all back together in a couple hours.

do i need any kind of spray or anything for the gaskets? i've heard and read that some people use some adhesive or something.


first timer here....on the bright side i have the book lol.

[MajesticTRX250R]

alright guys....thanks for the tips so far!!

i normally run straight 110 racing gas with 50:1 amsoil dominator....should i use a different ratio for the break in? or half 92 half 110...normal 2 stroke oil and not synthetic? ect?

[1promodfan]

O.K. I'm gonna break the ice. When I put mine together, I didn't use any kind of sealant. I know some people use 1211, but I didn't. Do you have a o-ring head? If you do, I usually rub a little bit of vasoline around the rings just to help them stay in the groove. If you have a regular style head, I think most recommend using some 1211. (Maybe someone will chime in that knows for sure)

I usually coat the cylinder wall and the piston with the oil that I mix with my gas. As in your case, I use Amsoil as well. For your break-in cycles you could mix it a little thicker, maybe 40:1 or 32:1. I think the race gas is fine for break-in. I used Amsoil for break-in and that all I run.

[Aceman]

Coat everything that's going back in your cylinder with premix oil. Piston, rings, wristpin, connecting rod bearings. I pour a little on the crank pin too just to make sure there isn't a dry start. When you install your reeds I'd put a little adhesive on both sides of the gasket too. Base gasket probably wouldn't hurt either looking back on it. Everytime I've leakdown tested I've found a base gasket leak and a reed gasket leak, don't take a chance, put a little adhesive on it now and save yourself some trouble. Folks seem to like the Threebond 1211, I picked up a tube but haven't had a chance to try it yet. I was using orange hi-temp silicone, works pretty good, but it's a pain to scrape off at disassembly.

[MajesticTRX250R]

got it all back together yesterday and started the break in procedure...got to step 4 where it says to run it for 10 minutes no more then 3/4 throttle....got up to 4th or 5th gear at a nice moderate pace and it died on me.

put it back in neutral and it started on the first kick but runs boggy...as soon as i put it in gear and start letting out the clutch it just dies...won't let me go anywhere but starts in 1 kick everytime....its idling like crap....i think she might have some gunk in the carb and jet....what do you guys think?

[MajesticTRX250R]

ok so here;s where i'm at....i cleaned the carbs and now i can ride again but it feels weak and definatly isn't running how it did before....maybe its running like that because of the rich oil and 50/50 gas mix i'm using for the break in?


reading the jetting thread in this forum and they say switch jets for the break in but i havent been doing that is that gonna cause problems? i haven't messed with any of my settings on anything except for the idling so it would idle...i got my cylinder honed and bored a size up would that make me need to change things?


i'm running everything the same before it blew up except for a more rich of a oil mix and i used a 50/50 mix of 92/110.

[MajesticTRX250R]

well now she will only start if i give it gas...then it won't idle or let me take off....carbs and jets are spotless.

won't start at all unless i give it gas while i kick it though.

[1promodfan]

Originally posted by MajesticTRX250R
well now she will only start if i give it gas...then it won't idle or let me take off....carbs and jets are spotless.

won't start at all unless i give it gas while i kick it though.

Well when I start mine, at the very bottom of the kick I'll give it a little bump on the throttle. It usually fires up then.

Majestic, where do you live? That has a MAJOR part to play in your jetting. Now even for my break in I usually mix a little heavy........like I went to 32:1......but when I ride I mix it at 40:1. I run Amsoil too and I've not had any problems.

As far as getting the jets right start with your pilot. You can even take your main out if you want. What carb. combo are you running now? What setup do you have? That'll help in getting some answers. Its hard to tell you where to go because every bike is different and so is the atmosphere.

[cdrookie]

once you settle on an oil ratio and jetting combo that works for you never change it unless you're adding parts(or taking parts off).

how does the spark plug look?
compression psi?
flywheel key still good?
flywheel tight?
crankbearings?
loose electrical connection?
carb vent tubes not pinched or plugged(same for the gas cap breather)?

[MajesticTRX250R]

alrighty, got it running and idling again but my idle screw has to be turned in all the way. its still running boggy i think thats because of the oil mix and the 92 gas.

i got a new rubbler sleeve going from my reeds to my carb i think that might of been leaking it had alot of little cracks in there....cleaned the carbs again and put in a new plug.


i did a compression test and i came out with 135...seems low to me? it has a 310 big bore, cool heads, rad valve, lrd big bore pipe, over sized radiator, ect....normally run 50:1 amsoil with straight 110.....i'm wondering if i need to torgue the bolts down tighter....i went by what the book says i don't know if its different or not? I'm about to go take her for a spin and try to run some of this gas and oil mix out of it.

[Aceman]

I gained 20 psi after break-in but was around 215 psi when I started, 135 seems way to low even for a pump gas dome. Maybe somebody else can verify that. If it was mine, I'd pull the head and verify the dome is correct. If that checks out, I'd check the ring end gap.

I'm actually getting ahead of myself here. You were holding the throttle wide open right? Verify with another compression tester before tearing into the motor.

[MajesticTRX250R]

yeah that was my thoughts too...way to low...i'm waiting for my neighbor to get home so i can borrow his tester and see....i had 90psi when it was blown 135 isn't much better lol.

how do i do a leak test? maybe i'm leaking somewhere?