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Discussion Starter #1
I'm curious what people have been running into when checking the 650 valves. Do you find they have needed adjustment when Yami recommends or do they stay in spec long past?
 

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At 6000 mi. I had a loose exhaust [.001"] and at 12000 mi. an intake was .001" tight . Well maybe a little less than .001 but I loosened it anyway.
 

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I got my 2006 VS650 with 9k miles on the odo.

I checked the clearance around 25k miles, and they were all within spec.

The bike has 42k miles on it now, will check them again maybe this summer.

It would be interesting to see if anyone checks them every 4000 miles like the schedule calls for, and kept careful records for which way they wear (if they get tighter or looser) and how long it takes for them to get out of spec.

There are two wear mechanisms going on with an overhead cam:

1. the valve wears against the face seal on the head, which will reduce the clearance, making it tighter.

2. the rocker arm wears against the cam lobes, which will increase the clearance, making it looser.

Interestingly, if the valve face wears and makes it tighter, the rocker arm contact to the cam would have pressure on it all the way around the cam, which would tend to make it wear faster and loosen up again...

so the two tend to cancel each other out, if the wear is the same on both metal to metal contact areas.

If it tends to wear to the loose side, the tappets will get noisy, but until it gets really loose it wont hurt anything, you just lose a bit of valve opening.

If it wears tighter eventually the valves will not close all the way, and the hot gasses will blown thru the exhaust valve burning it, and the intake valve will backfire into the carbs - both are not good. The odd thing is the tappets will quiet down when they are too tight, which sounds 'better', but its a negative indicator of trouble. A quiet air cooled engine without hydraulic lifters is an engine that needs adjusting.

Tappets gonna tap.
 

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The old saying "tappy valves are happy valves".
 

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Discussion Starter #5
I checked the clearance around 25k miles, and they were all within spec.



It would be interesting to see if anyone checks them every 4000 miles like the schedule calls for, and kept careful records for which way they wear
That's the kind of report I was hoping to hear. My last bike was a Honda DS and Honda calls for valve checks every 6k I think it was. Riders on the forums regularly reported that well past 20k they were still in spec and needed no adjustment. Glad to hear my new Yami might be the same.
 

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Discussion Starter #6
I got my 2006 VS650 with 9k miles on the odo.

I checked the clearance around 25k miles, and they were all within spec.

The bike has 42k miles on it now, will check them again maybe this summer.
I've always paid the shop to maintain my bikes (other then the basics, fluids and filters are easy for me to do), I'm curious why you would wait so long to check them? I guess you can just tell by the way the bike responds and how it sounds that they are not needing adjustment?
 

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I bought my 650 with 17,000 miles on it and I found the both exhaust valves tight by .003. From what I found out about the rest of the bike, I doubt the valves had ever been adjusted.
 

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If you check them yourself and follow the service manual procedure its a 3 hour job the first time you do it

when you get good at it maybe 2 hours

if you have a shop do it, 2 hours is at least $160 labor

I use to own air cooled VW beetles, I could do the valve adjustment in about 15 minutes. Its much more complicated on these bikes.
 

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why wait so long to check them? from what I have been able to find they do not drift out of spec very quickly.

If you read the maintenance schedule in the 650 owners manual they want you to check or lube or change bearings and parts just about every 4000 to 8000 miles, including pulling the steering head and swing arm apart and greasing the bearings.

To me that seems excessive for a casual rider. If I was racing the bike or running it full throttle all the time over very rough roads then maybe it would be more appropriate.

Back with air cooled VW beetles the valve adjustment was easy, and it was the same interval as the oil change: 4000 miles. I would usually find 2 or 3 of the valves were not in spec, or were at the limit, and I would tweak them back. But the difference is, that was a 1600 lb car with a 53HP engine. When driving a beetle it was normal to have your foot to the floor taking off from a stop, merging into traffic, and just about any hill was pedal to the floor in 4th or 3rd gear, all the way up. The engine was being run very hard at full throttle, and its max speed on level ground was 82mph.

By contrast I seldom have my VS650 WFO, its actually a long twist on the grip to get it all the way around to full throttle. On my Royal Star even less often, that bike takes off like bats from hell at half throttle from a stop.

So the short answer is: it takes me 2 hours to check the valves on the 650, and the last time they did not need to be adjusted, so that was two hours (and 4 new $4 orings) for no change.

When I check them next time I plan to leave the fake chrome plastic head covers off, so I can get to the exhaust valve tappets without taking anything off the bike. I think then if I check the exhaust tappets and they are good, I might not bother taking the carbs off and doing the whole two hour deal to check the intake tappets.
 
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