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Compression testing a 90' RM250

Joined
Aug 24, 2007
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#1
The guy at my bike shop suggested I check the compression on my RM250 and said to pick up a good compression tester at Autozone.. My problem is.. I have the compression tester but unsure how to use it! lol I kick it once, I get one reading, I kick it again, it goes higher.. every time I kick it I get more compression.. Whats the proper way to do this and what should I see copmpression wise for a normal RM250?

Also, when I pulled the plug out, I noticed the outside rim looked new, but the center looked dark brown. The tip was dark brown as well.

Dennis
 
Joined
Sep 12, 2006
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#2
Hold the throttle wide open, hold the kill switch in and kick the bike over until the gauge quits climbing, this will be your reading.

You can't read the plug under this circumstance, warm the bike up, shut it off, install a clean plug and then go do a throttle chop, stop the bike and read the plug.
 
Joined
Jan 10, 2008
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#3
I got a 1991 RM250 - they're fun bikes - and did the same. Top end isn't new but not bad. I did it awhile ago like posted above and the reading was around 140 - 150psi IIRC. A new top end, I believe, should read somewhere around 150-160psi depending on displacement. Someone correct me if i'm wrong.

On a side note - did your bike come with a kickstand? I got a bracket that looks as if that's what it's for but not sure haha Thanks and hope the above helped

TNutcher