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1976 XS500 Valve Adjustment


corlon
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i recently got my xs500 running after sitting for 3 years. the last issue i'm having is a noise coming from the right upper side of the engine. i'm assuming its the valves i hear. wondering if anyone can give me the specs for adjustment and the procedure.

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i recently got my xs500 running after sitting for 3 years. the last issue i'm having is a noise coming from the right upper side of the engine. i'm assuming its the valves i hear. wondering if anyone can give me the specs for adjustment and the procedure.

Clearance specs are .006-.008" for intakes, .008-.009" for exhausts. Adjust them at TDC on power stroke, using the TDC ignition timing marks in the breaker point housing. Adjustment is with a screw and locknut.

The noise could also be a loose timing chain. When you have the valve cover off you can see if the chain is loose. There's an "acorn" nut located near the cylinder/crankcase joint at the right front corner. If you loosen this nut the cam chain tensioner should "snap" against the loose chain and tighten it back up. Then tighten the nut back up. If it doesn't tighten up, something is worn...chain or rubbing blocks.

You should get a factory service manual for this bike. They are availible on eBay in CD form or paper. They aren't the greatest manual ever written but are much more informative then a few lines of infor here. And they have pictures!

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pulled the cam cover off today and checked the exhaust valves. they were within spec. the cam chain seems tight on top, but couldn't tell if the tensioner was good or bad from above. tried to adjust it by loosening the acorn nut on the right front of the engine, but nothing happened when i did that. if i pull the right side engine cover off will i be able to see the tensioner for the cam chain, or does more then jusy the one cover have to come off? curious as to why you only gave specs for the exhaust and not the intake? thanks again.

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Clearance specs are .006-.008" for intakes, .008-.009" for exhausts. Adjust them at TDC on power stroke, using the TDC ignition timing marks in the breaker point housing. Adjustment is with a screw and locknut.

It's possible I'm seeing things, but it looks like both the intake and exhaust specs are there to me....;)

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pulled the cam cover off today and checked the exhaust valves. they were within spec. the cam chain seems tight on top, but couldn't tell if the tensioner was good or bad from above. tried to adjust it by loosening the acorn nut on the right front of the engine, but nothing happened when i did that. if i pull the right side engine cover off will i be able to see the tensioner for the cam chain, or does more then jusy the one cover have to come off? curious as to why you only gave specs for the exhaust and not the intake? thanks again.

The specs for the intakes were listed: .006-.008".

If the chain seems tight at the top it's probably fine. The manual says if you loosen the tensioner nut you should hear it "snap" the chain in place...so I assume if you hear nothing then the chain is already tensioned correctly. There are some sprockets and some "rubbing blocks" in the assembly that I suppose could be worn and causing trouble. Maybe try turning over the motor by hand and watching the chain to see if all the rollars are there and there's no obvious worn spots on the chain. I think to investigate further you'd need to remove the motor from the bike and do more major disassembly.

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