Knocking engine - need your advise

HI everyone,

I went to look for a new bike today. Its'a 1981 KZ1000J.

The bike has around 50,000miles and never been rebuilt.

The bike seem to have been sitting for a few years without running. The new owner told me that the previous owner had put some oil in the gas tank to store it.

Now that the mix of oil and gas had pass, the bike start pretty well but revs around 3,000 to 4,000 rpm without any choke and after 1 minute or 2, it come back to normal speed.

My concern is on respect some bad knocking that can be hear at idle. It's not continuous but quite frequent. It' doest knock when riding but I doubt it.

The new owner tell me it might be the cam chain that need ajustment.

The carbs seem to need a good clean up. Would it be the cause for the high rpm and the knock in the engine (from too much fue in a cylinder?)

Thanks in advance for your help
Joce

If carbs are out of synch you can get a little cam chain slop at lower rpms,with that many miles it could also have a lose timing chain.

Ok. it aint no rattle. Really sound like a glunk glunk.... :ohmy:

Clean the carbs. When the carbs are dirty and a cylinder cuts out it often sounds like a knock. The revving also sounds like an air leak in the intakes somewhere.. While the carburetors are off, fully inspect your intake boots and any vacuum plugs for dry/cracked areas and replace them if in question. Unless you can do the work yourself, it might not be a good investment unless the bike is like under $600. Intakes and carb cleaning will easily set you back $400. And you might still have engine issues.....

A loose cam chain in those engines will make a knocking sound. It's the same in all Kaw motors with hyvo cam chains. Carburetors out of synch will enhance that noise significantly and can also make it knock at low RPM even if the cam chain is adjusted properly. You may have one or both problems. Both are easily corrected without braking the bank if you have mechanical skills.

Download the service manual.

Based on your symptoms the carbs need to come off for cleaning anyway. While they're off it's your perfect opportunity to address the cam chain tensioner. Follow the procedure in the service manual for tensioner installation.

Thanks

I can do all of that work. I just did'nt want to have to deal with major problem such has crankshaft or main main bearing problem.

The bike is clean and complete, so fir the right price, it might be a good bike

My guess is you might be hearing the clutch making noise because the carbs are not balanced. A rod bearing is going to sound deep. Keep in mind this engines are built to last. I have seen several Concours 1000's with 100,000 miles plus. There are a couple running around with 300,000 miles. Stand next to one of these bikes at idle and you'll swear the cams are coming through the valve cover at any second.

Like others have said, if the carbs are out of synch, these Z1/KZ motors will make some racket. In fact I thought the same was going on my 900. A friend of mine said with the amount of miles I had put on the bike it would have blown up if the noise was rod knock. A carb synch cleared a bunch of noise and it didn't sound like it was coming apart any more.

Might also check to see if the carb boots are old and cracked while you have the carbs off.

I wouldn't run the bike until you get the cam chain adjusted. I'm convinced a lose chain is what shredded my front cam guide. And that's a major a pain to replace.

Got the bike tonight.

#1 wasn't firing so this was causing the knocking.

Open up the carbs and they had a lot of dirt in it so cleaning them tomorow.

I've check the compression and was fine on all fine. #1: 125 , #2 : 120, #3: 125, #4: 135. Not motor was not really hot so will need to redo a little bit later.

Anyway, look like a score on a nice KZ1000J project.

Will post some picture soon.

Thanks for your help