been posting over on dirtrider.net since it's the biggest 2-stroke forum i've found, but it seems there's really only one guy there that knows much (nickyd)...  i'm messing around with an old 87 RM250, and need some feedback.

would greatly appreciate any feedback or opinions on the questions in this post:
http://dirtrider.net...ad.php?t=127295

TIA~ Trace

what the other guy said.  sure, you could stuff the new piston and rings in, and who knows, it could last a long time.  may as well do the job right- hone (and bore, if needed) the cylinder, use NEW gaskets, and make sure you got all the pieces of broke piston out of the bottom of the engine, or you will be doing it again very shortly!

I dont know where you ride, I ride trails and am often up to 30 miles from my truck.  I would rather miss one ride, fix it the right way, and be sure that I am not getting stranded out in BFE.  Also riding it this way could make it that much more expensive to repair later if it grenades.

thanks for the feedback.  i ride around a 130 ac ranch, so never too far from the truck.  the thing is it's more than a matter of just honing the cylinder - it needs to be bored & sleeved or re-plated.  ($$$)

i guess my biggest problem is i just want a newer bike, and will probably sell this one pretty soon.  if i rebuild the whole bike to totally pristine condition, it might be worth $800.  if it's clean, starts easy, and goes thru all the gears it's worth probably $500.  (full disclosure on condition, of course)  sleeving & boring the cylinder is going to cost at least $250 more.

my buddy had a 87, I dont think it had a plated cylinder.  Either way if you take it out and she blows, it aint worth much, if you dont ride it and sell as is with disclosure, you will likely get $500.  Then again you might ride it for months without probs.

Yo Trace, is there any play in the crank bearings? (Grab the magneto/flywheel by hand and lift up and down on it) If there is a definite movement or clonk from the main bearings then you are looking at ripping the motor apart. I've recently done the same with my '92 model and replaced every bearing in there. It just depands on how good you are with the spanners. I wouldn't bother wasting time on the top end if the bottom end is knackered. Sell it as it is to someone who doesn't mind repairing it, (oh, and don't reuse the gaskets). Cheers.

no, the bottom end seems solid, but i'm gonna have to split the case anyway because i have a blown crank seal.  (which was probably helping lube the bottom end too)  wouldn't be a bad idea anyway since the piston fragments were (are still?) down there.  i rinsed them out with my parts washer, but might not have gotten them all.

i've also found a broken exhaust valve which i have to repair or replace.  regardless, i've become determined to ride this thing again.    i did buy replated cylinder for $50 and a ball hone, and it looks like that's going to work.

Firstly, I better forewarn you that Wiseco pistons offer a shorter life span than that of most other manufacturers (about 6 hours on the rings, and 12 on the piston if you're an aggresive rider.) Be sure to watch the ring gaps, because I've seen several engines running Wiseco pistons after shattering their skirts.... and they're not a pretty sight. I'd recommend something like a Vertex next time.

      If my mind serves me correct, '87 or '89 was the year that Suzuki began plating their cylinders with Nikasil. So if you did get it plated, it does have an advantage as far as longativity goes compared to an iron-sleeved RM of the era. Be sure to mention that if you try and sell it and you may get a little more. If you haven't already, be sure to clean up any carbon deposits and check the ring gaps once you get the cylinder jug back on.

      The only gaskets I wouldn't recommend re-using are the cheap paper gaskets the factory offers on older bikes (newer, too? I wouldn't know.. too poor to own a new bike. ) Anything else is fine, just be sure to inspect for any damage to them and don't re-use them more than one or two re-builds. Some prefer to replace them every time, but it's not a must if they are in good condition.


      As for break-in, follow this: http://www.off-road....atv/breakin.htm

      When at idle during break-in, periodically give the throttle a little twist while staying in the lower RPM range to better lubricate the rings and cylinder wall, since low mixture velocity at idle allows most of the oil to remain in the crankcase. This is crucial during break-in because it allows your rings to seat more properly and offer much more life out of your rings and cylinder plating.

      Goodluck with your re-build, and I hope you found this helpful. Be sure to let us know how the ol' beast runs!  


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