compression test

easytravel · Posted: October 5, 2008, 5:05 pm Post subject: compression test

O.K. folks...simple question... what should my compression tester read for a stock '78 650 and the max deviation in reading? I will test tomorrow morning and post my results. Thanks in advance.

jayel · Posted: October 5, 2008, 5:38 pm Post subject: Re: compression test

below 100 rebuild 100- 145 ok 145-160 very good, should be within 10% of each other (5-6 lbs) prop the slides open and full open throttle butterflys when testng

xsjohn · Posted: October 5, 2008, 5:38 pm Post subject: Re: compression test

Throttle held wide open........150 great.......140 good.......130 ok........less not doing well........10 deviation might be livable for me.....but I can see it running along real smooth.............xsjohn

5twins · Full Member Joined: Aug 05, 2006 Posts: 1616

Testing a warm engine usually gives better results as well.

easytravel · Posted: October 5, 2008, 7:05 pm Post subject: Re: compression test

thank you fellas...full throttle, warm up first, I only use the kicker because the electric leg sounds like a coffee can full of marbles, this is sufficient yes? 3-4 kicks each side should give me the readings I need to determine the condition of the top end and rings? What can I say guys.. thanks again!

skippyp · Posted: October 13, 2008, 10:37 pm Post subject: Re: compression test

OK, so let me get this straight. Warm up the bike, remove the plugs and thread in the tester. It should only take 3-4 kicks to reach the desired numbers? What if it takes more kicks to reach a good pressure but the pressure still holds. I did a test before (not really knowing what I was doing) and didn't open the throttle, it took probably 10-15 kicks to reach 150psi, but it held that pressure for a long time. I am going to test again now that I see how it should be done. Anymore tips would be great, man this site is helpful!

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