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1979, CX500, Z, shaft drive.
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Discussion Starter · #1 ·
CX500 1979.Hi - I checked and adjusted the tappet clearances today as by the Haynes manual no problem. However when I rode today the bike did sound a bit more tappety. I correctly set the clearances on a cold engine. The gaps were a little tight if anything before I adjusted them and the engine wasn't as noisy. Should I tighten the gaps a little to reduce the tappety noise. The feeler gauges did slide in with a bit of resistance after adjustment. The engine ran well, pulled well, accelerated throughout but was a bit noisier. Thanks in advance
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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Do it again with each cylinder at TDC on the compression stroke. The clearances were tight yesterday because the exhaust valves were being pressed by the tappets
I don't know what process the Haynes manual describes (I haven't seen mine in years), but if you follow the procedure in the Factory Service Manual, you'll have it right.
 

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1979, CX500, Z, shaft drive.
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Discussion Starter · #3 ·
Thanks. The Haynes manual does give the correct procedure. I did set the pistons at TDC on compression on each side right hand first and adjusted to a sliding fit. I checked each valve before adjustment and the inlets in particular were quite tight. I adjusted each valve to the same feel on the gauges as well. Like I said the engine pulls and runs well just seems a bit noisier.
 

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These will sound a little like a sewing machine.
The FSM's procedure begins with the left cylinder (from the seated rider's perspective) at TDC on compression. (Adjust the camchain here, too, if you have a manual adjuster.) Turning the engine clockwise from the front, the next TDC of the right cylinder will be on the compression stroke.
I tend to set mine a little on the tight side, to keep the noise down, but not enough to burn a valve. If the specified gauge fits between the tappet and valve stem, but the next larger size doesn't, it will be in spec.
 

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tappety valves are happy valves. If you set them correctly cold do not tighten them up. Better to have them a little loose than a little tight. Another trick on 4v/cyl bikes is to use a long feeler and adjust both valves at once. Maybe this is already mentioned in the service manual.
 
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The Factory advises Left (shifter side) first and do the cam chain adjustment while you're at it, then the right. Take your time adjusting, make sure the drag is equal on all valves when pulling the feeler through. These are like solid lifters and should make a little noise. Sewing machine-like. It takes practice. Murray sells a tool that makes finding TDC a breeze.
 

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When set properly the next larger feeler gauge will not pass through.
 

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1979, CX500, Z, shaft drive.
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Discussion Starter · #10 ·
The Factory advises Left (shifter side) first and do the cam chain adjustment while you're at it, then the right. Take your time adjusting, make sure the drag is equal on all valves when pulling the feeler through. These are like solid lifters and should make a little noise. Sewing machine-like. It takes practice. Murray sells a tool that makes finding TDC a breeze.
Thanks for the information. I redid the settings as others said and am happy with the results - happy days.
 

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'84 CX650E that is evolving into a GL500
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These bikes do tend to have a bit more valve train noise than some other models because of the pushrods and the valves are easier to hear because the heads stick out past the tank.
My summer bike (GL1100) has the heads at ankle level with belt driven overhead cams and when I change to the CX in the fall it takes me a while to get used to how noisy its engine is.
 

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tappety valves are happy valves. If you set them correctly cold do not tighten them up. Better to have them a little loose than a little tight. Another trick on 4v/cyl bikes is to use a long feeler and adjust both valves at once. Maybe this is already mentioned in the service manual.
Yeah off-topic but owners of honda dohc bikes always go Looser than Fsm values... but on those bikes clearances diminish with kms/ miles...
 

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Discussion Starter · #13 ·
I wasn't happy with the noise still from the tappets so decided to redo them. I followed the instructions closely and got set up to do the left cylinder with piston correct at TDC. No real issues here although the gap was a bit tight. Loosened off and moved onto right side. Again set piston at TDC and checked gaps only to find the inlet was massively over the .08mm. Transpired that when I set them I hadn't noticed the .08 and .09 feelers guages were stuck together meaning the resultant gap was twice as big!!! Readjusted and now runs sweetly again. So the moral is check how many feeler gauges you're measuring with!!!!
 
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