rebuild, what should i do

[byza_dog]

k, doing a rebuild on my 08 250exc

went raceing at the local mx track on the weekend, 2 firsts and a dnf coz me powervalve is stuck shut, just carbon, so i am cleaning it all out and seeings the bike has 87hours on it i am going to do a piston, rings and all the gaskets and stuff.

so the questions

1, seeing i can do it all without takeing the head off the cylinder should i just leave it on or take it off and put new o rings in?

2, the manual shows 4 different gasket thicknesses for the base gasket, i think standard is .5mm what will a thinner gasket do for me? or thicker?

3, should i do the crank bearings? if its something you check on when its appart how do i check?

4, which parts are interchangeable from the 08 sx and the 08 exc? coz the shop couldnt get me a powervalve gasket when i did the rings last time, so i had to make one from gasket paper.

just keen to know the differences betwene sx parts and what i should do while ita appart, i have no rush to get it done and want to do anything i should while i am at it even if it doesnt need doing quite yet. and i have all the tools and stuff to do it myself so it wont cost much.

thanks for any help

[RayIn]

Use the same thickness base gasket as the old one. Measure it, or take it in to the shop to match it up. That way you don't have to unbolt the head - if you can get the head and jug off together.

The more complicated way is to use the base gasket that gives you the correct X-dimension. You can search how to do that right here, but you have to take the head off.

I wouldn't do the crank bearings unless there was a signal they are bad. Changing them requires splitting the case.

[byza_dog]

thanks for the reply.... i am relatively new to 2 strokes so any info helps

this is my first one, had it since last november

what would be a signal that they are bad...

i just took the jug off and left the head on cylinder to do the rings so its pretty easy, was just checking if its worth my while doing the head.

and yeah i will just use the same gasket again

[roverracer122]

never reuse gaskets

[Stephenjmccoy]

I always reuse gaskets. On much higher performance sleds too. Never gave me a problem. And a signal that the crank bearings are bad is, well you would hear them. Good luck!

[urgreathero]

if ur doin whole rebuild why wouldnt u put new gaskets in it, why even gamble with a chance with your old ones failing lol

[Ttoks]

gaskets only fail if you fail to put gasket sealant on them, there's no harm that can be done by reusing gaskets, sure buy a new set incase you brake the old one, but if you can reuse the old one keep the new one as a spare.

as for crank bearings, the the clutch and flywheel cover off, and see if theres any side/side or up/down movment in the flywheel or primary drive gear out of the engine (may need to remove the clutch basket to check the engine side), any movment at all warrents replacment, a little in/out movment is normal

[byza_dog]

thanks ttoks trust an australian to give me a good informative reply that answers my question i appreciate it

and no i dont re use gaskets i meant same gasket as in same size maybe i needed tomake it more clear but thats too ****ing bad sorry for the language give me bad gas ?

bye and thanks