1.6i Posted February 4, 2007 Report Posted February 4, 2007 I did a compression test today, i warmed it up for about 10-15 minutes..removed both plugs and held it wot, kicked till the psi didnt go any higher.. both cylinders were @ 105psi I bought it in 04 brand new, all i have done to it is t5's k&n pods, 340's (switched to 330's last time out) needle moved one clip up. sea level. the numbers seem too low for me, i used a brand new matco compression gauge too.. unless i have a faulty gauge the numbers are low, the engine hasn't fouled one plug on me and runs great! i keep up with my boy he has t5's vforce 2's, a pro design cool head and k&n pods..his top end is alittle worn though but we're pretty even up the hill.... My question is, will compression numbers make that much of a difference from the engine simply being warmed up compared to the bike being ridden assuming that the engine gets alot hotter when ridden, given the chance for the rings to seal better??.... i have no where to ride the shee before a compression test, unless i take the bike out for the day then test it after a ride.. another thing i noticed was its been leaking coolant recently when i ride out in glamis..it doesnt leak all the time, just sometimes.. TIA guys.. Quote
FireHead Posted February 4, 2007 Report Posted February 4, 2007 Where is it leaking coolant from? 105psi is pretty low, but as long as it is even between the cylinders, that rules out quite a few things. You shouldn't need to have the engine warm to check the compression. How many hours do you figure you have on the engine? Quote
bansheefreak Posted February 4, 2007 Report Posted February 4, 2007 its lil low.. i would get a noss head and bump up the compression.. when you take stock head off look at cyls and see how they look might be time to rering or rebiuld.. Quote
dajogejr Posted February 4, 2007 Report Posted February 4, 2007 It is standard procedure to warm an engine to check compression...normally you'll see a few PSI higher when warm. Keep in mind also...if the threads on the tester are not as long as the threads on the spark plug, you'll show a few PSI lower, too...you're not filling all the volume in the chamber that a spark plug would. That being said...yeah, it's top end time. I'm sure it'll run fine for a little while.... Depending on clearances when you get it all apart, it might need a hone and re-ring, might need a fresh bore and pistons/rings. Where does it seem to be leaking coolant from? Quote
Snopczynski Posted February 4, 2007 Report Posted February 4, 2007 did you have the throttle wide open when checking it? Quote
dajogejr Posted February 4, 2007 Report Posted February 4, 2007 I did a compression test today, i warmed it up for about 10-15 minutes..removed both plugs and held it wot, kicked till the psi didnt go any higher.. both cylinders were @ 105psi Yep... Quote
1.6i Posted February 5, 2007 Author Report Posted February 5, 2007 thanks for all the responses, i have no idea where the coolant is coming from, it seems to be coming from the radiator area when it does leak, it doesnt leak a whole lot but some.. thats why its hard to see where its coming from.. As far as hours on the engine, well you figure ive had it since 04 i have taken it out these past 4 seasons about 4-5 times each season and i kill about 6-8 gallons roughly each time i go out running K2 @ 32:1 for a while then swtiched to 927 still @ 32:1.. i use to ride it hard all the time but not anymore..lol.. I was planning on putting a cool head soon, ill check out the cylinder and piston for and scoring at all... ima get a snap-on compression tester from a friend here @ work and see what the psi differences there is if any..ill keep you guys posted.. Quote
Banchetta Posted February 5, 2007 Report Posted February 5, 2007 At sea level, you should be up around 125-128psi..no doubt your ready for a rering, or rebuild if the cylinders are egg-shaped. Buying a head will increase your compression, but don't use that to solve your problem at hand...low compression is from worn rings or scarred cylinders. Where your cylinders are =, that is a very good sign meaning your jetting is not a culprit nor you have any air leaks. Most likely you just have normal wear of the rings...Thin rings will tend to break and pieces will scar the cylinders and get into the crank. Better to change them now and overhaul the shee. It'll be cheaper now and not ruin a day of riding..You WILL beat your boy after that. No doubt. Especially if you add a head as well as overhaul. Quote
Animalman294 Posted February 5, 2007 Report Posted February 5, 2007 At sea level, you should be up around 125-128psi..no doubt your ready for a rering, or rebuild if the cylinders are egg-shaped. Buying a head will increase your compression, but don't use that to solve your problem at hand...low compression is from worn rings or scarred cylinders. Where your cylinders are =, that is a very good sign meaning your jetting is not a culprit nor you have any air leaks. Most likely you just have normal wear of the rings...Thin rings will tend to break and pieces will scar the cylinders and get into the crank. Better to change them now and overhaul the shee. It'll be cheaper now and not ruin a day of riding..You WILL beat your boy after that. No doubt. Especially if you add a head as well as overhaul. Dead spot on, except I thought that stock compression was between 130-135 psi................. :thumbsup: Quote
dajogejr Posted February 5, 2007 Report Posted February 5, 2007 Dead spot on, except I thought that stock compression was between 130-135 psi................. :thumbsup: Mid 120's are always what I've found... Quote
1.6i Posted February 5, 2007 Author Report Posted February 5, 2007 so its normal for the rings to wear down so fast? i mean damn, after how many hours of riding are rings known for lasting especially on a stock engine? seems to fast to be needing a top end already imho.. Quote
Banchetta Posted February 5, 2007 Report Posted February 5, 2007 so its normal for the rings to wear down so fast? i mean damn, after how many hours of riding are rings known for lasting especially on a stock engine? seems to fast to be needing a top end already imho.. Well you are in San Diego, so I'm guessing your checking this at sea level?? Higher elevations will make your compression lower...2 years is not much and you should get more than that...You are running a good K&N w/ adaptor kit and outerwear right? The stock flange will let sand get by and wear your rings. Another thing is make sure you warm the shee up slowly. Revving the hell out of it on a cold motor will wear them faster as well especially w/ forged pistons...Also what are you running for oil? Try to stay at 32:1 ratio w/ a good oil. Some people like to run 50:1 or 80:1, thats just insane..I'm old school and got 5 years on my last build and only lost 3psi. Oil can only help. I also believe in the cast pistons like stock or pro-x. They warm up and expand at the same rate as the cylinder where forged pistons like wiesco will heat up and expand faster than the cylinder. There is a lot of controversy on this subject, so I'm just giving my experiences over the years. For longevity, go cast. If your at sea level, then maybe get another tester from someone and double check your numbers. Make sure you hold the throttle wide open on testing and don't stop kicking until the needle stops moving. Quote
Banchetta Posted February 5, 2007 Report Posted February 5, 2007 BTW, we're heading out the 12th-21st to Glamis. I'll be flying into San Diego. You guys should come visit us. We'll have 2 tractor trailers, 8 or more rvs and about 75 guys at Pad 2. We're the East coast group, most Glamis locals know of us. Maybe we'll meet up. :thumbsup: Quote
1.6i Posted February 5, 2007 Author Report Posted February 5, 2007 Well you are in San Diego, so I'm guessing your checking this at sea level?? Higher elevations will make your compression lower...2 years is not much and you should get more than that...You are running a good K&N w/ adaptor kit and outerwear right? The stock flange will let sand get by and wear your rings. Another thing is make sure you warm the shee up slowly. Revving the hell out of it on a cold motor will wear them faster as well especially w/ forged pistons...Also what are you running for oil? Try to stay at 32:1 ratio w/ a good oil. Some people like to run 50:1 or 80:1, thats just insane..I'm old school and got 5 years on my last build and only lost 3psi. Oil can only help. I also believe in the cast pistons like stock or pro-x. They warm up and expand at the same rate as the cylinder where forged pistons like wiesco will heat up and expand faster than the cylinder. There is a lot of controversy on this subject, so I'm just giving my experiences over the years. For longevity, go cast. If your at sea level, then maybe get another tester from someone and double check your numbers. Make sure you hold the throttle wide open on testing and don't stop kicking until the needle stops moving. im running K&N pods, with outerwears, installed them when the bike only had like 2-3 hours on it, never had them fall off while riding..yeah i learned in high school auto class that reving a cold engine is a big no-no, (oval piston in a round cylinder when cold)...so i never did that with anything ive owned .. i use to run 927 then K2 then switched back to 927 recently always 32:1.. ima try my buddies tester tomorrow and see what that gives me..thanks for your opinions.. Quote
FireHead Posted February 5, 2007 Report Posted February 5, 2007 Just for a sanity check in this coversation.............................everyone knows that most piston aren't oval shaped right? They are design as a series of offset ovals. THe manufacturing process they go through to get that shape is called cam turning or eccentric turning. Some oddball engines throughout history have actually used oval shaped pistons that were very noticeably shaped that way. I can think of a couple of Honda GP engines that did that. I think the design requirement that spawned that was a retardedly high rpm limit. I might be able to remember more after I eat lunch. :shoothead: Quote
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