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Discussion Starter #1 (Edited)
I am in need of a little advise. I bought earlier this year my dream bike: an air cooled '85 GPz750 (ZX750 A3/ Ninja750R) with full original fairing. It was one of those bikes I really wanted when they just came on the market but at the time never was able to afford. The fact that I was 13 at the time had also something to do with it.

Earlier this year I thought that the time was right to search one out. I wanted one with a bit of work and found one on E-bay. Paid £300 for it and to my surprise it passed the MOT first time round.

I spent the rest of this year not only riding the bike but also returning it to an original state and I am sort there or there abouts.

However, like any good old air cooled 750 Kawasaki it has a very noisy bottom end at tick over. I have been told that the primary chain could be the cause of this or maybe the clutch basket is worn. although the latter is a new one to me.

If the problem was the chain the engine will need a complete strip down in order to replace the chain and I am OK with that. But is it like a normal chain to the rear wheel whereby you would also need new new sprockets? because that would mean a new crankshaft as well. Has anyone replaced a primary chain before and are there any tips you could share with me.

Obviously before I strip the engine down I'd like to know if there are any other causes of a noisy bottom end (keep it clean!) that might be a bit easier to to repair. Is the clutch basket a common problem?

Thanks

Ben
 

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U may not need to strip the bike down too get the chain and sprockets off, Replace chain and front and rear sprockets. always. if that doesn't fix it, you may have a drive gear problem, check your oil change as needed. (these sounds should be on the left side) Right side noise (clutch side) when ideling and it feels like its clunking around inside and the same feeling wail moving it may need springs or a new assebely. U can get someone to do your drive line or pick yourself up a chain bracker (that may save u down the road) rivet kind no master link those may fail..... oh ah what kind of noice...
 

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Discussion Starter #3
Thanks Bobbyhill,

I've already changed the chain and sprockets recently. The primary chain I was referring to is inside the engine. On these old air cooled bikes the drive from the crankshaft to the clutch was a "hy-vo" chain. I will take you up on your tip to check if the noise comes from the clutch end though.

The noise is a very loud rattle from inside the block at tick over. At about 1500rpm it's gone. It is worse when the engine is cold.

Ben
 

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sync the carbs propery, this will fix alot of your problems..

there is really no need to replace this chain. it is loose and sloppy from the factory, it doesnt stretch. i recommend you do not open the motor unless absolutely necessary.

I raced one of these bikes last year and had the motor apart a few times solving issues with the wiseco piston kit and some annoying oil leak issues (i never had a failure). The motor always scared me while idling (with increased compression it makes even mre noise!) and even on the track if i did not wear ear plugs for a practice session the engine noise was almost too much to bear!! :):)

with a bike of this age, although i got quite a bit better at putting the engine back together is not something i would recommend the average bloke to do on his own.
 

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A buddy is having the same kind of issues, And he found that its the cam chain and cct. doing this is not all that hard. bike haven't really changed all that much in this area.
 

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Discussion Starter #7
A buddy is having the same kind of issues, And he found that its the cam chain and cct. doing this is not all that hard. bike haven't really changed all that much in this area.
FYI you have to split the cases to change the cam chain.
Ta gents,

Much appreciated. I think I'll try to balance the carbs first before I do anything else. See if I can get a carb balancing set from somewhere.

Ben
 

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Alot of the noise in my 84 went away when I cleaned up/deburred/lubed the cam chain tensioner: I would say a "must do" before cam chain replacement. I did mine during a head gasket replacement, but I did not see where the head needed to come off. The carbs? Very likely, but this is the piece of maintenence that you should do. Like valve adjustment and those swingarm bearings!

Just my experience on a 35,000+ mile motor.
 

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Hello, I'm assuming you have a Turbo model and if thats the case it is more than likely the cam chain tensioner. You can pull it off and clean it or you can convert it to a manual tensioner. If you go to www.750Turbo.com you will find a wealth of information on how to do it. David
 
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