Fre530d Posted September 25, 2006 Report Share Posted September 25, 2006 Hello Just bought a second hand banshee and from 2005, september so it's only a year old. The guy told me that he only drove 50 hrs with it. Now i have bought a compression tester today and tested my compression on a warmed up engine and I only measure 85PSi left and 90PSI right. It still runs real good, but it's my first shee so I have nothing compare it with. It start first kick and feels like it has enough compression. The engine is very clean , no oily gaskets etc. so probably my pistons and rings are worn. Is this possible after only 50 hrs or is the guy full of shit? What are the best pistons to buy? Will it be a big difference after I rebuild it? Wfg Fred Quote Link to comment Share on other sites More sharing options...
dajogejr Posted September 25, 2006 Report Share Posted September 25, 2006 What is your elevation? That can have a HUGE effect on static compression. Also...it starts first kick? I'd try another compression tester... Normally, if compression is that low...and you're at or near sea level...it won't start unless you push start it....or kick your leg off... Hell, my old bike had 105 or so PSI...and it took me 8 or 10 kicks to start it up.... Quote Link to comment Share on other sites More sharing options...
baddsheee Posted September 25, 2006 Report Share Posted September 25, 2006 90 is pretty low. Depends on you elevation. You should be looking at aroung 125PSI at sea level. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted September 25, 2006 Report Share Posted September 25, 2006 90 is pretty low. Depends on you elevation. You should be looking at aroung 125PSI at sea level. 125ish new. Not with 50 hours on it. Quote Link to comment Share on other sites More sharing options...
Fre530d Posted September 25, 2006 Author Report Share Posted September 25, 2006 (edited) Hello It starts first kick. I am at sealevel. (maybe 180 foot or so) I bought a 90 dollar "made in USA" compression tester so I don't think that will give any fault readings. Will test again tomorrow, maybe I didn't turn the threads hard enough to seat well in the cyl head? Grtz Fred Edited September 25, 2006 by Fre530d Quote Link to comment Share on other sites More sharing options...
dajogejr Posted September 25, 2006 Report Share Posted September 25, 2006 Also... Be sure the thread lenght of the compression tester is the same as the spark plug thread length...the chamber or dome must be full, as it would be in running conditions, to get a true reading. If the fitting is shorter....you can easily add quite a few PSI...but probably less than 10. For 60 bucks you can get a complete small engine and automotive tester...you went top dollar... If it still reads the same, try squirting some 2 stroke oil in each of the cylinders....and try the reading again. If it bumps up pretty good from the oil...then, you're due for a top end. I just can't believe it'll start that easy if the compression is accurate!! Another dumb question....you did hold the throttle wide open when kicking, and you kept on a kicking until it would no longer climb, correct? Quote Link to comment Share on other sites More sharing options...
Fre530d Posted September 26, 2006 Author Report Share Posted September 26, 2006 (edited) You asked a very smart question actually because I forgot to open the throttle :baseball_bat: Will do again today and post the readings Wfg Fred Edited September 26, 2006 by Fre530d Quote Link to comment Share on other sites More sharing options...
Fre530d Posted September 27, 2006 Author Report Share Posted September 27, 2006 Hello Tested compression again today with throttle fully opened. Only 90 PSI :shrug: I putten the longer threaded measuring thing in and still the same, engine was hot Sealevel Afterwards I put some 2-stroke oil in the cyl head and the compression raised only about 5 psi. And it starts first kick ALWAYS, strange isnt it? I unscrewed both plugs at a time and tested one side and then the other side, maybe I must leave the spark plug in the hole when i am testing the other one? WFG Frederick Quote Link to comment Share on other sites More sharing options...
dajogejr Posted September 27, 2006 Report Share Posted September 27, 2006 Nope...I remove both plugs (easier to kick...) Well...if your confident your gauge is accurate, it's top end time. The only other thing you can do is take the cylinders off and measure piston to wall clearance, then ring end gap...but, hell, once you get down that far...it makes sense to put a fresh top end it. To be honest...something doesn't sound right, I'd try another tester. 90 PSI and that thing would probably have to be pull started, IMO..... Quote Link to comment Share on other sites More sharing options...
peterlocal22 Posted September 27, 2006 Report Share Posted September 27, 2006 Nope...I remove both plugs (easier to kick...) Well...if your confident your gauge is accurate, it's top end time. The only other thing you can do is take the cylinders off and measure piston to wall clearance, then ring end gap...but, hell, once you get down that far...it makes sense to put a fresh top end it. To be honest...something doesn't sound right, I'd try another tester. 90 PSI and that thing would probably have to be pull started, IMO..... i know that yu have to keep kicking it over until the gauge stops moving but on average how many kicks is it? ive done like 20 kicks and the meter is only at 50 psi. yes it is still going up but it seems like i will have to kick it over 100 times. also some one told me to becarefulk building up to much pressure because it can blow out seals inside the motor? any truth to that Quote Link to comment Share on other sites More sharing options...
shatodavi Posted September 27, 2006 Report Share Posted September 27, 2006 You're making a bigger deal out of this than you need to. Just rering the sucker. It'll cost you about $150. From my experience, unless you are testing with either a snap-on or Craftsman compression guage your readings are suspect anyway. I would feature to guess that your compression is actually higher than the 90 reading you are getting but after 50 hours of running its time to re-ring anyway. Do it before the piston is ruined and you have to buy a piston as well. Or worse the cylinder walls get scored. Just my humble opinion. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted September 27, 2006 Report Share Posted September 27, 2006 also some one told me to becarefulk building up to much pressure because it can blow out seals inside the motor? any truth to that Nope...now...I wouldn't leave the gauge on for 3 or 4 days on end... You're measuring cylinder or cranking compression. Now, if you're talking leak down test, you don't use more than 6PSI...cause that can damage seals. Shato...I agree. My buddy is a city mechanic, and he has a snap on gauge. My other bud had an el cheapo automotive gauge. He tested his triple snowmobile, and I don't remember the exact specs, but one cylinder was 180, one was like 130...and the other was like 145. And this thing ran great. With the snapon....it was 140ish all across the board.... Quote Link to comment Share on other sites More sharing options...
Fre530d Posted September 27, 2006 Author Report Share Posted September 27, 2006 Thx for the answers guys, The compression tester is from the brand "midlock" Maybe someone got the same? Wfg Frederick Quote Link to comment Share on other sites More sharing options...
vitovito240 Posted September 27, 2006 Report Share Posted September 27, 2006 can i still check my compression even though my radiator and pipes are not hooked up? thanks Quote Link to comment Share on other sites More sharing options...
black sunshine Posted September 27, 2006 Report Share Posted September 27, 2006 Hey Fred, Just tested mine last night with a Matco PSI guage, got 85psi in both. Mine also starts first kick and runs pretty good. Im at about 1000'. My buddy is going to check the calibration on his tester tonight, just to be sure. Just thought I'd throw that out there 'cause I thought I'd have other telltale signs that my compression was that low, poor starting, ect. Quote Link to comment Share on other sites More sharing options...
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