Hey guys,
I own a 1999 vmax 500 deluxe with 1100 mile. The sled is in mint shape and I bought it form the second owner. It has always started right up and run strong. The other day I took it out of the garage to fire it up for the first time since last season. It started up fine and I ran it for 15 minutes. After I ran it I though I would do a compression test on it. It turns our that both cylinders were exactly the same at 95 PSI. This has me worried because that seems very low especially because of the low miles. Could this be wrong. My throttle was not wide open, the engine was warm, and it hadn't been run in a long time. Im not an expert mechanic so let me know what you think. If it needs new rings I might just go on and sell it before its to late. Thanks any input is much appreciated.
I own a 1999 vmax 500 deluxe with 1100 mile. The sled is in mint shape and I bought it form the second owner. It has always started right up and run strong. The other day I took it out of the garage to fire it up for the first time since last season. It started up fine and I ran it for 15 minutes. After I ran it I though I would do a compression test on it. It turns our that both cylinders were exactly the same at 95 PSI. This has me worried because that seems very low especially because of the low miles. Could this be wrong. My throttle was not wide open, the engine was warm, and it hadn't been run in a long time. Im not an expert mechanic so let me know what you think. If it needs new rings I might just go on and sell it before its to late. Thanks any input is much appreciated.
super1c
Super Moderator
The number is not so much the thing to watch for. Its the difference between the two. If both cylinders are 95 i say your ok. Each comp tester is different, each way of testing is different. You can do it cold, warm, wet, dry ect.... Could be a bad tester, hose length makes a difference. Point is i think your just fine. Key is now to use same tester and same way to check the compression from time to time. I check mine with my preseason maint. Then as needed, always using same tester and same way. If you want you can try a different tester and see what you get. I know that number seems low but i doubt both cylinders would be down the same amount.
Devilin AblueDress!
New member
X2. Common thread in everybodys process is to have throttle wide open. The little bit of fuel/oil mix helps lube cylinder/rings for more accurate numbers. Guessing if you pulled the belt and WOT you would get a higher PSI, how much? Your guess would be as good as mine. Like Super1c said its them being even of close...except with vipers LOL!
Thanks guys I appreciate the help. Ill be sure to check the compression as the season goes on. One thing that concerned me also was I used the same tester on my other sled which is a 2000 vmax 700. I got 120 on the end cylinders and 115 on the middle cylinder. The only difference between that test and the one I did on the vmax 500 was that the 700 was cold and had not been run. But I do understand there are a lot of different variations that could occur when you are doing a compression test.
Also super1c when you talked about your pre season maintenance what kind of things do you look over. So far I just checked the chain case fluid because I changed it last season, changed out the plugs, replaced the air filter, and checked the oil lines. Is there anything else I should look over before I hit the trails?
Also super1c when you talked about your pre season maintenance what kind of things do you look over. So far I just checked the chain case fluid because I changed it last season, changed out the plugs, replaced the air filter, and checked the oil lines. Is there anything else I should look over before I hit the trails?
staggs65
Moderator
clean carbs
super1c
Super Moderator
X2 on carbs for sure. As far as preseason im a little to the extreme side im sure. But wrenching on sleds keeps me sane. I can only talk to myself for so long. LOL! (I have a lot of time off with my job, home all day by myself). For all the sleds i clean the carbs (complete tear down), clean the powervalves ( you wont have), drain and take apart the chain case for a once over then adjust. Adjust throttle, choke freeplay. Recopper seal exhaust joints. Pull, disassemble, and clean clutches and belts. Remove skid and take every wheel off and clean and repack. Redo all skid shims and replace bushings as needed. Remove drive/speedo bearing and jackshaft bearing for cleaning and repacking. I get made fun of by my buddies but my sleds run strong and are flawless. Oh yea then that compression test. I just do it dry and cold, (story of my life LOL! Except wet somtimes LOL!) full throttle with plugs out and belt off. Same tester same way every year. And always drain gas in spring when i put them away and alwayays use premium to fire back up in fall. I run premium at all times. Told ya i have way too much time on my hands.