bode1 Posted November 20, 2008 Report Posted November 20, 2008 Just installed new top-end with ported jugs, new pistons, and 20cc cool head. My compression is 140 & 145, I am at sea level. This is after about 15 minutes riding. Everything seems OK. Does my compression seem like it is in the right ballpark, and how long after rebuilding are the rings seated enough to get a accurate compression reading. This is with a crappy tester, I lent mine to someone and it's not even really that good. Plus with my better one, I have to take my tank off to test it. Quote
06shee325 Posted November 20, 2008 Report Posted November 20, 2008 Glad to see you're back up and running. Sorry i don't know accurately about your question but i have seen some wheres on here if you are under 110 you need a rebuild, so i would say that is great compression. P.S. Howd them shocks work out for ya? Quote
dajogejr Posted November 20, 2008 Report Posted November 20, 2008 Use the good tester.... I've seen a crappy tester vary 30PSI from one cylinder to the next on my buddy's triple sled, slapped my snap on gauge, dead on. After 15 minutes, your rings are seated. Quote
bode1 Posted November 20, 2008 Author Report Posted November 20, 2008 The shocks are sitting on my workbench. One project at a time. I have to check something first, but may be able to ride tomorrow, may change my jetting too Quote
bode1 Posted November 20, 2008 Author Report Posted November 20, 2008 Use the good tester....I've seen a crappy tester vary 30PSI from one cylinder to the next on my buddy's triple sled, slapped my snap on gauge, dead on. After 15 minutes, your rings are seated. That's the thing, my father in law gave me this tester. It's kinda like a homemade pocket type of deal. He is a mercury mechanic. My better tester is a $30. one from an autoparts store that I can't use w/o taking off the tank. it seemed like it was only fire intermittently on the left cylinder after a few minutes warmup, and a couple of passes around the yard. I called my buddy, and he felt that I just fouled a plug due to some oil used during assembly. So, I checked compression was 140L & 155R. Changed plugs (left was fouled) ran for maybe 15 minutes on some trails behind my house and came back and rechecked compression and than it was 145L & 140R. Overall, it seems to run good, I was hoping to be a little higher with my compression, but was told I would not be able to run pump gas with smaller domes. They're close, so I'm happy I guess, Will try to get a better tester for a more accurate reading. Thx Quote
dajogejr Posted November 20, 2008 Report Posted November 20, 2008 A 30 dollar auto store tester is one I've seen give false readings... Craftsman, Snap On, Matco...etc. I promise a good compression tester is cheaper than a new top end...LOL. Depending on how agressive the port is...those numbers seem about 10PSI low, give or take. Quote
bode1 Posted November 20, 2008 Author Report Posted November 20, 2008 A 30 dollar auto store tester is one I've seen give false readings...Craftsman, Snap On, Matco...etc. I promise a good compression tester is cheaper than a new top end...LOL. Depending on how agressive the port is...those numbers seem about 10PSI low, give or take. It's an HJR dune port. You're right about the better one being cheaper in the long run. I'll probally buck up and buy a craftsmen tester. or borrow lol a good one. Quote
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