Hi

I have been advised by a main dealer mechanic that I have low compression in all cylinders on my (8500 miles on odometer)03 600RR. Theproblem manifested itself as the bike refusing to start, despite a fully charged battery. I checked oil level, fuses and everything that the Honda service manual suggested. I thought I had it traced to the oil pressure sensor, but that wasn't it either. The low oil pressure light was still illuminated and the engine wouldn't start. I took it to the main dealer on a trailer with what I thought was an electronic/electrical problem. They tell me that it is either a valve, cylinder or cam chain problem most likely caused by a lack of oil. It'll be at least $800 (on top of the $300 to get this far) in labo(u)r … before any parts! Some have suggested that it would be cheaper to source an engine on ebay and have it switched for the one in my CBR.

Any advice would be welcome.

Thanks

Gavin

 

Have you tried putting a bit of oil in each cylander?

I had a friend who had his pistons get gasolene washed... no compression at all. A bit of oil and voila, compression was back... once it was running he was fine.

At all but the shadiest dealerships that should be cheaper to fix than buy unknown from ebay. Unless there is more to the story than you've told us, I can't think it should be as catastrophic as all that.

 

The cheapest I have seen a used motor for is around $1,000.00. So, you really wouldnt be saving alot, plus it could be damaged as well. I never really heard of what Woot said. But at this point it couldnt hurt to try.

 

I gotta tell you, something doesn't sound right about that ! Even a low compression engine will start. I get cars in all the time that have 1/2- 1/3 the compession they should, and they still run. Gas washed rings will cause low compression, but should not cause NO comp. Unless s/thing nasty happened the last time you rode the bike, s/thing that would make you think the engine was failing, you should consider getting a second opinion before you spend any money w/the guy telling you its a comp problem. Also ask him what the readings were, and verify. 50lbs in an engine designed to produce 150 would be a real problem, but say 110-120..... should still run fairly well, altho w/a lack of power. Sounds really fishy tho, and I'm not usually one to bad-mouth mechanics. Did the bike quit last time ? Stall ? Or was it ok when parked then would not start ? The former may indicate a problem like the one he is describing, the latter would make me think he's wrong, or trying to rip you off. Also possible that he doesn't know whats wrong and is covering his @ss by telling you its an engine problem.

 

+1, get a compression tester and see for yourself, $15.00

 

Check th e cam timing, I'm willing to bet one of the cams jumped a tooth or two. A buddy of mine (old guy, but he'll kick all our asses on the track!! hahah) just bought a "new" track bike for $500 ('98-ish Kawi ZX-6R), bought it cuz it didn't run and had low/no compression in all cylinders. I was over at his house right after he brought it home, and we started tearing into it. Sure enough just as he suspected, intake cam was 1 tooth off. Check it out, might be all it is! I find it quite rare to have a motor with ALL cylinders low compression without having some sort of valve timing issue. 1 or 2 maybe due to head gasket, rings, burnt valve, etc, but not all 4, especially if they're equally low. Try the oil in the cylinders first though see what that does.. I've had cars get fuel washdown before, and they'll crank and crank and crank and won't start

In this case with my buddy, he's still scrapping the motor cuz he found other problems (tranny won't shift into any gear but 1st), and a few other things, so he's just gonna find a good used motor to stick in it.

 

I've worked on a CBRwith the problem you described.After doing everytning possible I pulled the head off and found that everything was so carboned up that the valves weren't closing all the way. the bike would start hard and run like crap. So I had to take all of the valves out and clean everything. Your timing shouldn't have jumped and if it did your very lucky a valve didn't hit a piston. thats how sport bikes get thier high performance by having such tight tolerances and if everything isn't perfect something bad will deffinetly happen.

 

alot of good advise here, but NONE of us here can say "thats exactly what it is" because there is alot of things that cause low compression.. my advise to you is to just get a buddy and rip apart the motor... i did that myself with my DR650S (single cyclender) but still. turned out all that was wrong with it was my timing was off 1 tooth on my single cam.. lol.. alls im saying is find out what is wrong your self (with a buddy) THEN start guessing what it could be and so your notspending money to fix what you THINK is wrong. you will be spending money onwhatyou KNOW iswrong..

example #2.)
one of my buddys XR600R's stoped running all of a sudden,but it had spark, comprsion and fuel.. and it blew our minds why it would not even fire! Turned out, a tiny little key in the magneto was shredded! 4 bucks later it fired right up!