New Owner - Valve adjustment?

If it's broken or just needs tweaked

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Joined: Wed Oct 17, 2007 9:13 pm
Location: New York

New Owner - Valve adjustment?

Postby AR_Guy » Wed Oct 17, 2007 9:22 pm

My Nephew and I just bought a 1980CBc with 15,xxx miles on it. It runs a little rough but has been sitting. The issue we have is that the engine is VERY noisy. Someone told us it needs a valve adjustment. Where can I find directions on doing this and is there something else I should watch for?

Thanks in advance. I look forward to learning a lot on this forum and plan on posting updates on our project.

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Re: New Owner - Valve adjustment?

Postby Volker_P » Thu Oct 18, 2007 1:01 am

Welcome here! :D

When the bike was sitting for longer, checking all the things and settings like valves, plugs, camchain is a good idea. Also replace air filter, oil and oil filter. Engine noise may in fact origin from the valves, however my first look would be the cam chain. There is a semiautomatic tensioner, you just release the 10mm closed nut at the rear center of the cylinder bank a few turns and tighten it again while turning the engine by hand at the crankshaft right side with a 24mm wrench or socket. Sometimes the tensioner is blocked and it helps to release also the upper bolt (just a bit, you probably won't get it in again otherwise!) just above the adjuster nut which is the second mount of the tensioner. Cam chain tension can be directly checked best with a screwdriver when the top center engine cover is away e.g. for valve adjustment. The valve settings are quite tight, 0.05mm intake and 0.08mm outlet.
What you really want to have before you start is probably the online manual where all the procedures are described with pictures: and
Don't hesitate with further questions.

Looking forward to the photographs. :wink:

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Postby Ibsen » Thu Oct 18, 2007 1:02 am

Welcome to the forum. 8)

A couple of things that normally adds noise to these engines are an untesioned cam chain, valves that needs adjustment, and carbs out of synch. You start with the cam chain adjustment, then the valves, and if it still isn't idling smooth you synch the carbs.
How to adjust valves and the cam chain: ... et=tlx_new ... et=tlx_new

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Joined: Wed Oct 17, 2007 9:13 pm
Location: New York

Postby AR_Guy » Thu Oct 18, 2007 10:01 am

Thanks Guys! I'll try it this weekend. My engine looks slightly different than the one shown in the those pictures, but I'm sure it will work fine.

My Nephew wants to rush in and modify the bike. My experience with old cars tells me different. I want to get it running right (adjust engine, bleed brakes, etc) and ride it some before the weather gets too bad here in New York. Riding it will tell us what needs fixing during the cold winter months.

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