CB1000 top end blowout... - Sportbike Forum: Sportbike Motorcycle Forums
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post #1 of 6 (permalink) Old 05-21-2002, 02:14 PM Thread Starter
Join Date: May 2002
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CB1000 top end blowout...

Ok.. I love this bike and really don't want to ever part with something no one else has (for the most part). It's a 1994 cb1000 (exported to usa only in '94 and '95), liquid-cooled, etc... aka "The Big One" if you like nicknames.
I sought this bike out specifically and found one used in WA state. The bike has performed perfectly for me for the 4 years I've owned it now.. and now has about 50k miles on it.
Situation is.. I'm riding with my girlfriend to a VW meet.. long steep grade at 90mph. A little faster than normal highway speed and an extra passenger. Halfway up the hill without warning the power cuts on me. I can keep it revving a bit by treating it like a dirtbike throttle - but.. it's gonna die in 10 seconds as a I roll to a stop anyways. Towed it.. blah blah. Compression check shows 165 lbs on 1 & 3.. and 60 lbs on 2 & 4. Having hydraulic valves and such.. my mechanic can't deal with it and sends me off to Honda of Hollywood. There I am waiting for a diagnostic and the bad news.. I'm told, given the miles and the potential problem of bent valve stem, blown rings, whatever.. that just putting on a bandaid of a top end valve kit is wrong. I'm just dismayed with his wanted to do a total engine rebuild so this problem doesn't occur with the new top end. $2500 and ANOTHER month without my bike. /sigh... On top of this.. I have not ever really been able to find a CB1000 forum out there... Anyone here have one? or GOOD experience with one? In the meantime I'm riding my girlfriend's CB1 -- kinda like it's little brother. Thanks for reading this winded post. Advice on the bandaid fix or total rebuild would be appreciated..
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post #2 of 6 (permalink) Old 05-21-2002, 02:27 PM
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welcome to the forum, I'm sorry to hear about your troubles. I don't have much advise except to get another opinion, $2500 seems kinda high for a rebuild, how much for just the valve fix. is the engine stable, or was it before this happened? I've been in this situation with cars before, it sucks. I usually ended doing the rebuild myself rather then letting a shop do it, works out to be only a few hundred buck that way, and you only need a few days to do it, atleast with a v8
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post #3 of 6 (permalink) Old 05-21-2002, 02:45 PM Thread Starter
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ya.. new member here../thanks!
For just the valve kit, etc.. he kinda quoted around 400 bucks... and yes.. the bike has always been stable, reliable... pretty much perfect.. except.. I may have noticed over the past year.. the bike feels like it wants to bog down and stall (almost as if the kill switch is flipped, but not so severe) when I open throttle past three quarters.
Plus.. as for doing the job myself at home.. and not having any experience doing a rebuild... I don't have the special equipment for this bike. Even the local mechanic said he didn't have the right stuff for this one. This is the price of wanting a bike different from everyone else...
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post #4 of 6 (permalink) Old 05-21-2002, 03:04 PM
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does he take the engine out to do the valve kit, if so couldn't he just toss in a re-ring kit for a few hundred more, what about other honda dealers in the area? or even other bike shops (kawasaki, suzuki, yamaha) around here they all do pretty much the same jobs.
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post #5 of 6 (permalink) Old 05-21-2002, 03:45 PM
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hydraulic valves???
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post #6 of 6 (permalink) Old 05-21-2002, 03:54 PM
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Re: CB1000 top end blowout...

Originally posted by Pyrus
The bike has performed perfectly for me for the 4 years I've owned it now...... Halfway up the hill without warning the power cuts on me.
That doesn't sound like a burnt valve. They tend to go gradually because they don't burn all at once. I thought the engine in them was the same as the CBR-1000 and if so, they're not hydraulic lifters but screw adjusters. I have 55,000 miles on a CBR-1000 that I run the wheels off of regularly and the only thing I've done to it beyond regular maintenance and valve adjustment every 15,000 miles or so, is a cam chain and tensioner this past winter at 52,000. The symptoms there were not performance related but a little chain rattle when cold that quieted down after about a minute running. I would get a second opinion and look at carb diaphragms, dirty gas screen above the petcock, water in the gas, plugged tank vent, and things like that. If they are mechanical adjusters, check adjustment too, and if any are tight... then maybe you do need a valve job.

One word of caution when doing a compression check. The throttles should be open when turning the engine over. This is recommended any time you use a compression gauge but is not often done on cars to no real problem because they all draw from a common manifold with one set of butterflies. This affords a large reservoir of air to draw from and being common to all cylinders, still accurately detects disceptancies between cylinders. On a motorcycle, the very short intake runners and the fact that they have individual butterflies means you get a less than full fill of the cylinder with the butterflies closed causing your readings to be lower than actual, but worse yet, they are likely to be erratic from slight variations in carb sync. This will indicate trouble that may not be there. Make sure the compression check was done with the throttle open.

Another thought... I know you said a compression check was done but if someone made this call from spark plug coloration, remember that 1-3 and 2-4 are common to the ignition coils and ignition system. It could be coincidence but it makes me say hmmmm. Hope that helps. I'd get another opinion from a good independent. You must have some of those around your area. Maybe Hammer or somebody out there could recommend one. Hope that helps.

BTW, I'll ask around a little here and see if someone can confirm whether or not that has hydraulics, or are you sure of that yourself?

Edit add: If they are mechanical adjusters and you've never adjusted them, start there. I re-read your description and that sounds like it could be tight valves, too. If you do have any tight ones, they may seal up with adjustment but may burn in the near future from damage started by running tight.

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Last edited by Dad; 05-21-2002 at 04:18 PM.
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