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anybody done a compression test to a cr 500

15K views 12 replies 11 participants last post by  coolcatmat11 
#1 ·
hi i have a cr 500 engine in a trx 250 and finally get a modification done to the kick start to start it .but i found dat it ain t had much compression when i try to start it .i get 90 psi i m at sea level .the compression tester new and i use it on my shee already .so let me kno wa i m suppose to get and the cylinder has a full drag port job done to it .thanks :blob5:
 
#2 ·
I'm not sure how much comp. it should have, it varies thoughout different model years, but 90 psi is way too low.
 
#3 ·
thats way to lie should be 170+
 
#4 ·
90psi is too low to run any bike. Put some new rings in her and it will be okay. If the cylinder is scratched with grooves then a bore job is needed.
 
#5 ·
yeah that sounds way to low. sure you kicked it fast so the air didnt leak thought the rings? on a side note i saw this on ebay. i wish i could have been there see them try to do this....

"I LEARNED A VALUABLE LESSON WITH THIS MOTOR: ALWAYS GET THE COMPRESSION READING WITH THE MOTOR IN THE FRAME! I TRIED AND TRIED WITH ANOTHER GUY TO GET A GOOD READING FOR ALL YOU POTENTIOAL BIDDERS. IT WAS ABSOLUTELY INSANE! BOTH OF US ENDED UP WITH BUSTED ANKLES AND WRISTS! (YOU CR500 GUYS KNOW WHAT I MEAN) THE POINT IS, THIS MOTOR HAS REDICULOUS COMPRESSION."

http://cgi.ebay.com/ebaymotors/ws/e...STRK:MEWA:IT&viewitem=&item=300180918329&rd=1
 
#8 ·
90 lbs compression

when a cylinder is ported to drag race the exhaust port timing is usually raised a bit, which would lower comression when the motor is kicked over, but the pipes sonic waves overcome this, filling the cylinder better a high rpm,s. However i,d pull the pipe and reed cage and take a peek at the damage.
 
#9 ·
fourtrax250r said:
"I LEARNED A VALUABLE LESSON WITH THIS MOTOR: ALWAYS GET THE COMPRESSION READING WITH THE MOTOR IN THE FRAME! I TRIED AND TRIED WITH ANOTHER GUY TO GET A GOOD READING FOR ALL YOU POTENTIOAL BIDDERS. IT WAS ABSOLUTELY INSANE! BOTH OF US ENDED UP WITH BUSTED ANKLES AND WRISTS! (YOU CR500 GUYS KNOW WHAT I MEAN) THE POINT IS, THIS MOTOR HAS REDICULOUS COMPRESSION."
If these guys broke their ankles and wrists they have no business owning a 500cc smoker. Stupid people do stupid things. :angry5:
 
#12 ·
150 ish on a stock motor...
 
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