Scootdog: a compression test is done with the engine turning, just to see how much pressure the cylinder developes. A leakdown test is done with the engine stationary and sealed (valves closed...) to see if it can maintain pressure. This is to check the condition of the cylinder walls and rings. An engine in good condtion should lose pressure pretty slowly. Typically if the engine is losing pressure dry, they'll squirt a little oil into the cylinders to help seal the piston rings. If it maintains pressure then, you look at the valves instead of the bottom end for problems.

 

Scootdog: a compression test is done with the engine turning, just to see how much pressure the cylinder developes. A leakdown test is done with the engine stationary and sealed (valves closed...) to see if it can maintain pressure. This is to check the condition of the cylinder walls and rings. An engine in good condtion should lose pressure pretty slowly. Typically if the engine is losing pressure dry, they'll squirt a little oil into the cylinders to help seal the piston rings. If it maintains pressure then, you look at the valves instead of the bottom end for problems.

 

Jason,

They checked the compression last week and found it to be low, right? So now they are using the leak down test to isolate the area of the problem, as AJ650 states, rings or valves. 98% leak-down? Is that on both cylinders or is it only on one? If the compression was low on both cylinders then the most likely cause is worn rings. There's not much chance that you've got a valve problem on both cylinders. The main thing I don't understand is that they have had the bike for over 2 weeks? What the heck have they been doing? Do they not consider you a priority, are they waiting for Kawi approval or are they just slack. Did you have any luck with Paula or are you waiting on your dealer?

Steve

 

If that leak-down test indictes 98% leakage, that is indicative of a MASSIVE failure ,as in hole in piston(s), or burnt/bent valves. Did the tech tell you WHERE the leakage was going? Pressure in crankcase=pressure getting by/thru the piston. Pressure out airbox=open/bent/burnt intake valve. Pressure out exh.pipe=open/burnt/bent exh. valve. On the other hand, if the leak-down is only 2% YOU have a tight engine! I believe that up to 10% leakage is acceptable to most auto manufacturers, anyway.

 

You guys are right, the reason we go by leak down tests instead of compression tests is the compression release. The only thing a compression test will tell you is what your compression is when your engine is being turned over by the starter. On the other hand a leakage test will tell you everything you nead to know about the cylinder, rings and valves. When we do a leakage test we use a tool with two pressure guages, one that tells you what the pressure is going into the cylinder and one that tells you how much is pressure is left over in the cylinder. And by turning the crank slowly you can check the whole cylinder for gouges or holes. Like trx450 said when your engine is cold around 10% of leak by is acceptable, if you got 98% you got problems. Tell the guy thats doing the test to make sure bolth valves are closed and put him on the spot a little and ask him where the leak is from, if its from the carb its intake valve, if its from the pipe its exhaust valve and if its from the oil filler its rings or cylinder if he tells you where its leaking by and they fix it ask to see the parts. Oh yea how many miles are you at now?? I've seen some 650s around here with over 10000km and still run like new and the valves settings were still in spec. Pretty toough motor. Let us know what you find out though.

 

i realize what a leakdown and comp test is aj, you do it at the top of the comp stroke. doing it anywhere else ,
would be giving a bad reading.

 

scootdog--- You are among the living! Have you been punching your pal in the neck lately?

 

Yes BTW I'm haveing a massive heart failure. I've beem Bike less since (April 11th I think so next week is a whole month). We are waiting on mine side right now because I don't want to move until a final word from Kawi shows up, so indirectly we are waiting for Kawi because I don't want to do a thing until Kawi says whats up. Paula was great and she couldn't do a thing so off to her boss she sent me... I got good feelings there and time will tell. Freedom is very busy but doing as much as they can for me I really hate waiting however when it comes to importance I don't want anyone else to suffer because of my issues. I'm starting to get antzy now because I'm missing runs and my stress level at work is a record high so I NEED MY BIKE BACK SOON. Now what I need to know is if they can be testing the bike wrong I'm aware of everthing so far in this fourm for issues. Next is if it's that bad how come I can pass a suzuki vision, I don't think they are that slow LOL Next is it clears up and runs great after it's going, and most of all there wasn't one weird noise? and it idles at normal. and if I'm riding with 2% of my engine left you would think it would run like $hit. Also this happened fast; I started it up let it warm up and loaded it on the truck drove for a 1/2 hour and from there it took an hour to start it, but before this happened I would say it wasn't starting easy but it would start normally like choke one small prime and 1/4 throttle and it would start in about 5 seconds. Since then we only got it started twice. I'm interested in the leaking around the air intake that alltoys was talking about. I haven't been on it for weeks so I'm still 62 km shy of 15000 km ~760 hours. When I get it running it doesn't backfire or burn oil and I dried the little oil I leave in my airbox and no oil is comming in. I also think I noticed that my fan wasn't cutting on as often but it was hard to tell cold day etc... I've been adding oil on a 1-2 week basis (about every 400 km) since the 8000 km mark but plugs always looked good even the rear one! With 98% failure I don't feel I can get that result by normal wear any comments? I just found out everyone that I need to talk to I can not reach until monday[img]i/expressions/face-icon-small-sad.gif[/img] so here goes another week.

 

Jason,

I'm betting on worn rings. Especially since you've been adding oil for the last 7000k. With low compression it would start real hard but probably run fairly normal after warming up. As far as the 98% failure, they must have done something wrong in the test. For it to be that bad the bike wouldn't run, period. If you need a ride fix come on down, maybe my wife will let you run her 360. LOL [img]i/expressions/face-icon-small-smile.gif[/img][img]i/expressions/face-icon-small-wink.gif[/img] Seriously, hope your up and running soon. I know when the stress level is up nothing beats a blast through the trails. Hang in there, we all feel for ya.

Steve

 

Kawi650,
I think Scotia650 nailed it dead on the head with rings as the problem. I used to race Harley with oval shaped pistons they would go perfectly round after being warmed up. The only way to start the little darling was with ether you should try this. If it will start fairly well after warmed up then it is rings. If you have to replace anything whether it be rings, or valves or bearings. If either one of these need to be replaced then do the entire engine not just what needs to be done. If you do only the part that needs to be replaced stress will be ten fold on the other worn parts and they will wear even faster than before resulting in more engine work. If you need one thing do it all it will save you in the long run unless you intend to dump it.