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1978 kz 650 sr - rocker cover removed - questions about service to top end 14 May 2024 13:16 #899024

  • xstreamcanadian
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I have a 78 kz650 with an auto tensioner. I just took my cover off also, no need to touch the tensioner that I could see on mine. I assume its different? I also checked my valves and all seem to be right on spec but two are slightly tighter clearance wise that the spec. its a low mile bike and it appears that it had some top end work done by the torque paint on the rocker clamps or whatever they are called and the timing marks as well. my tensioner wasnt working due to sitting forever and i had adjusted it earlier. I thought possibly i had jumped a tooth which is why i popped the cover off. Counted links, aligned marks, checked clearances. are slightly too tight clearances a sign of valve issues? everything appears to move freely and easily. 

anything else i should check? found out that the gasket is NLA, ordered one from fleabay and the guy sent a broken one... helpful. ordered the rubber caps from the stealership. 

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1978 kz 650 sr - rocker cover removed - questions about service to top end 14 May 2024 13:25 #899026

  • Wookie58
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Valve clearances reducing due to wear over time is normal
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1978 kz 650 sr - rocker cover removed - questions about service to top end 14 May 2024 13:26 #899027

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Valve clearances tighten with mileage.  If you have valves measuring at less than the required clearance, you should change the shims.  And while there, you may as well adjust them all.  Aim for the top end of the clearance range, since that will give more time before the next time you need to adjust.
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1978 kz 650 sr - rocker cover removed - questions about service to top end 14 May 2024 13:32 #899028

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ahhh... ok makes sense. here i was thinking less is better... doh!  ok. looks like Ive got a bit of work to do. pull the tensioner i assume, remove the cams and the caps just pop off? shims underneath? 

cheers 

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1978 kz 650 sr - rocker cover removed - questions about service to top end 14 May 2024 13:38 #899030

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ahhh... ok makes sense. here i was thinking less is better... doh!  ok. looks like Ive got a bit of work to do. pull the tensioner i assume, remove the cams and the caps just pop off? shims underneath? 

cheers 
First thing, measure the clearance for each valve and write it down.  After you remove the cams, and buckets, take note of what shim size each valve has currently.  Then, it's simple math to figure out what shims you need.  Many times, when doing this, you can move shims from one valve to another, reducing the number of shims you have to purchase.
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1978 kz 650 sr - rocker cover removed - questions about service to top end 14 May 2024 13:50 #899033

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That makes good sense. Thank you sir. Any magic to removing the cams? Ill have to go through the book again and of course youtube. What is the running symptom of low clearance? I guess depends if its intake or exhaust? I believe only two were out of spec but all were very close to the minimum so I suppose all would need different shims to get to the top of the spec. Thank you so much by the way. Much appreciated. Im wondering if this could be my hard start gremlin

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1978 kz 650 sr - rocker cover removed - questions about service to top end 14 May 2024 13:53 #899034

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would the procedure be:

take clearances and note
remove tensioner 
remove timing chain and secure somehow up top (zapstrap?) 
remove intake cam
remove exhaust cam
adjust with new shims
install cams and set up timing marks 
install tensioner 
take clearances again
install new gasket and cover 


 

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1978 kz 650 sr - rocker cover removed - questions about service to top end 14 May 2024 13:58 #899035

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That makes good sense. Thank you sir. Any magic to removing the cams? Ill have to go through the book again and of course youtube. What is the running symptom of low clearance? I guess depends if its intake or exhaust? I believe only two were out of spec but all were very close to the minimum so I suppose all would need different shims to get to the top of the spec. Thank you so much by the way. Much appreciated. Im wondering if this could be my hard start gremlin
Not necessarily, from new they would not have all been the same (compensating for manufacturing tolerances) so it is not uncommon for some to be right for a different valve. Symptoms of tight clearances would be low compression, lack of power, fouled plugs etc. They would need to be very tight to cause hard starting (not impossible) ultimately the long term effect could be burnt valve seats etc.
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1978 kz 650 sr - rocker cover removed - questions about service to top end 14 May 2024 14:05 #899037

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the plugs were pretty fouled. i guess once done at least Ill know they are correct and ill move back to the carbs. 
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1978 kz 650 sr - rocker cover removed - questions about service to top end 14 May 2024 16:48 #899050

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I just recalled a 650 motor i tore apart and was in boxes. I recovered 8 random spacers from the depths of my crawl space. I also have a complete bike in the back yard behind my greenhouse so I will pull the cover and cams and grab those ones too. Fingers crossed i will only need to purchase a few or none. I can also practice on the parts bike to get some confidence in removing the cams and replacing them in the correct spots 

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1978 kz 650 sr - rocker cover removed - questions about service to top end 14 May 2024 17:31 #899055

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Sounds like you have a good plan. Good luck. 
1976 KZ 900 A4 kzrider.com/forum/11-projects/613548-1976-kz-900-a4
1976 KZ 900 B1 LTD
1978 KZ 1000 B2 LTD
1980 KZ 750 E1
Kowledge Speaks, But Wisdom Listens.
Jimi Hendrix.
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1978 kz 650 sr - rocker cover removed - questions about service to top end 14 May 2024 18:32 #899062

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1978 should have a manual tensioner. Not 100% manual, but not automatically adjusted. The way this tensioner looks is it has a 10mm head bolt sticking out the side with several threads visible and has another 10mm head nut on the bolt tightened against the tensioner. The way you adjust this tensioner is rotate the engine to the correct position outlined in the manual which I can't remember off hand, then loosen the 10mm head nut, loosen the 10mm head bolt. Spring tension then takes up chain slack. Tighten the bolt, Tighten the nut and you are done til next time. With this tensioner no need to worry or fool with in any way during valve adjustment.
The fully automatic tensioner they used in 1979 and later for a few years can be identified by a single 10mm head bolt tightened flush to the body. This tensioner you need to put in a longer 10mm head bolt during valve work to lock the tensioner from moving, then when done reinstall the short bolt. I say this just so you know what to expect from the tensioner as someone can replace either version for the other.
For valve clearance adjustment in my opinion and experience, work with one camshaft at a time. It doesn't even have to be removed completely. First of course remove the center tensioner, then loosen and remove the cam caps on one camshaft. Lift the cam up carefully keeping all chain slack between the cams, keep the chain tight going down into the engine. Lay the cam in the center of the engine. Now you can remove the buckets and swap shims. Carefully move the camshaft back in position the same way keeping the chain tight going down into the engine. Reinstall and torque the caps, but you'll regret if you go more than 6ft/lb at most.
Now you've done one camshaft and haven't fricked up the timing. Do the other camshaft the same way. No worries of timing errors.
321,000 miles on KZ's that I can remember. Not going to see any more.
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