XXSTAR Posted November 26, 2006 Share Posted November 26, 2006 it is a 1982 CB900C About a year ago I was coming back from Memphis, we were doing 100 to 110mph for about 70 miles when I got back to town the bike was running rough. next morning I check the compression # 4 cyl 0 compresstion, all the other cyl were ok. pulled the engine then the head it had one burnt ex. valve. my question did running it this hard burn the valve or was it going to burn anyway? was it running lean. the bike has always run great idel smoth. thanks Ron Quote Link to comment Share on other sites More sharing options...
airborneXX Posted November 26, 2006 Share Posted November 26, 2006 it is a 1982 CB900C About a year ago I was coming back from Memphis, we were doing 100 to 110mph for about 70 miles when I got back to town the bike was running rough. next morning I check the compression # 4 cyl 0 compresstion, all the other cyl were ok. pulled the engine then the head it had one burnt ex. valve. my question did running it this hard burn the valve or was it going to burn anyway? was it running lean. the bike has always run great idel smoth. thanks Ron If the carbs are stock you're running lean. How did the plugs look? Did you ever check the valve clearances, if the valve is out of adjustment it will burn. I've run mine at those speeds for longer amounts of time with no troubles and stock carbs, so I'm guessing the valve was out of adjustment. Hurry up and get it back on the road, they are a great bike. I still love riding mine once in a while. Quote Link to comment Share on other sites More sharing options...
rockmeupto125 Posted November 26, 2006 Share Posted November 26, 2006 it is a 1982 CB900C About a year ago I was coming back from Memphis, we were doing 100 to 110mph for about 70 miles when I got back to town the bike was running rough. next morning I check the compression # 4 cyl 0 compresstion, all the other cyl were ok. pulled the engine then the head it had one burnt ex. valve. my question did running it this hard burn the valve or was it going to burn anyway? was it running lean. the bike has always run great idel smoth. thanks Ron If that one carb was a bit lean, running that long may have overheated that cylinder, precipitating a valve failure. Or its possible that one valve was just at the limit of its adjustment due to incremental wear, and the prolonged trouncing took it past adjustment and then precipitated its failure. Good bikes, but that's asking a bit much of a classic vehicle that's not prepped for it. Quote Link to comment Share on other sites More sharing options...
XXSTAR Posted November 26, 2006 Author Share Posted November 26, 2006 it is a really great bike. it has little less than 20,000 miles on it. I should have had it back on the road. I like that ten speed in the hills. you can leave it in 5th on most hills, at " THE GAP " I ran it in 4th and 5th. if anyone has a change to buy one in nice shape I would get it. it does not do any one thing really well, just over all a very good ride. I hate typeing!!!!!!!!!! couple of stories about this bike. I bought this bike about 3 yre. ago. first bike in 30 yrs. I got it Thursday at 4 pm. had the shop check everything out, 4am Friday morning headed out to " THE GAP " with 13 other bikes, 6 H-D, { 2 NEW } of corse the H-D had to be out front, if i got out front they would have to stop, anyway at one of the stops the 2 NEW bike riders as me why I would buy a old bike like this when I could get a real bike like theres, I ask them how much they paid for theres $ 28,000 each I replyed I can buy 31 CB900 for what you paid for that one H-D, I didn't hear another word from them. I will tell the other story later to much typeing. I know I can't SPELL ASS HOLE Quote Link to comment Share on other sites More sharing options...
airborneXX Posted November 26, 2006 Share Posted November 26, 2006 It's real fun when you smoke 'em on a 20+ year old bike It's nice having two different bikes like a sport bike and a cruiser type bike. The high / low gearbox is awesome, plus I like it when people look at it and wonder why the 2 shifters. It's not the fastest or the best handling bike out there, mainly due to it's weight, but I've been known to lose a few inexperienced sport bikers in the twisties. I've got about 32,000 on mine now with no problems. I bought from the original owner about 3 years ago for $1500. He took real good care of her, so the restoration was very minor. I adjusted my valves at around 28,000 miles and several were out of adjustment, some tight some loose. It was the first time they were checked according to the original owner. I'm thinking this was more of the cause of the valve failure than a lean condition. Most lean failures I've heard of are piston failures, but anything is possible. Now may also be a good time for a big bore kit I have a bunch of odd parts laying around for these bikes, so if you need anything let me know. No motor parts though, I parted out an 81 earlier this year and sold the motor as a complete unit. Quote Link to comment Share on other sites More sharing options...
Warp11XX Posted November 27, 2006 Share Posted November 27, 2006 Here is my old '82 girl. She is always up for a good run. 90K miles on her and I've worked the motor over pretty well. She strokes out about 125 horsepower at the tire now...WAAAAY too much motor for the ancient suspension designs and handling qualities. She'll scare the shit out of you and make you love every minute of it. [attachmentid=5222] Quote Link to comment Share on other sites More sharing options...
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