1990 RM 250 maintanence

Joined
Dec 6, 2003
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#1
I was wondering how often I should replace my rings and piston? I read the manual and it says every five races. The problem is, I don't race the bike and would like to know these answers in hours. My bike puts out a lot of white smoke for the firt couple minutes. What causes this? Is 20:1 sound like the wrong mix? That's what the manual says for the bike. Any suggestions would be great!
 
Joined
Nov 18, 2003
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#2
dear mud;
u can save yourself many hours and many more $$, if u will spend ~20 now, and buy eric gorrs book. i have ridden for 24 years now, and it has much in it even i did not know. tons of pics, etc. see excerpts from it at www.ericgorr.com.

anyway, it will diagnose your issues here, but until then: i think that bike has only one piston ring, in which case this requires more freq replacement than 2 ringers...so, if u are slow, which u probly are (nothing in the world wrong with that), AND you use top grade oil, AND you keep your air filter clean and oiled with a quality air filter oil, AND you allow your bike to warm completely up before riding it, THEN you can probly go 20~25 hrs of Novice style riding...."probably" being the key word. FYI: a 2-stroke is ready to take a slow lap once you have idled it long enough that you cannot leave you bare hand on its head no more than 2 secs.
 
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#3
whoops, sorry mud, forgot your other q's:
1. if the smoke is blue/bluish, then it is running too rich at that particular moment.
2. if the smoke is truly white, then u may have a bad rt hand crank seal.
3. so, before confusing u wit hdiagnosing a bad seal, try this:
buy some bel-ray mc-1, and mix it according to the directions (50:1). ride your bike and see if this helps. if so, u r on the right track. your jetting is apparently off, given all other variables are ok (clean air filter, fresh gas, etc.)
At this point you will need advice from a local pro at your track, or better yet eric's book.
 
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#4
it all depends on how hard u ride your bike, how well you warm it up b 4 rifing it, the quality of premix oil u use, and if u religously clean and oil your air filter with air filter oil.
if u obey the above rules, AND you ride at the novice level, on a single-ring piston (as most suzuki's are), then i would expect u to get 20-25 riding hours on it, or 15 racing hours...
 
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Dec 6, 2003
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#5
I will try all of the above out and see what happens! Thanks for the advice on the maintanence! As for a ragular mix should I go with something like 40:1 or 32:1. I take it the 50:1 mix is only to run the product you talked about to test with. Other than that thank you both for everything!
 
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Oct 22, 2003
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#6
Have a local shop do a compression test and that will tell you the true condition of the ring, but if it was my bike put a vertex piston in it. Suzuki 250's runs a 2 ring since 1995. Do you hear a rattle, common in 1990-1993 when the piston/rings were worn? Kick it over and you should have some resistance, if not replace it. A 2 stroke almost always smokes when started until it is warmed up, but if it is WHITE smoke, you have a problem. It will also have a smell of antifreeze if you are blowing white smoke, and it doesn't go away after it is warmed up. Ask a local pro at the track and he can tell you immediately by seeing it.

Back in 1991, we added a extra base gasket and had a performance shop mill the head to compensate for the extra gasket and it will plain rip. This changes the port "timing". In 1996 yamaha offered in its Yamaha YZ Wrench Report and recommended racers to do this, although it was offered as a kit. This will do the same thing for the Suzuki of the 1990 vintage. It will give it a sweet pull throughout the range...invest in eric gorrs book...enough said...