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Discussion Starter · #1 ·
I just completed my second valve clearance check at just under 53,000 miles. The second time through took less than half the time, about 2 hours, that my first attempt at 26,000 took just to get to the point that the valve cover was off and I could get to point of checking the clearance. The intakes are all within spec .008" fits - .009" doesn't. The spec in the book is .006" to .009". However, all of the exhausts are just a hair tight. A .006" fits snuggly but a .007" doesn't. The spec in the book for the exhaust is .007" to .010". What's your opinion on whether .001" of an inch tight is likely to cause any issues? The first time at 26K all were within spec and no adjustment was required. It seems like a lot of extra work for measly .001". Especially since removing the cam to change shims involves a lot more risk to screw something up than just doing the check does. Plus it means the bike will be down for several days to order the correct shims as the dealers don't seem to have an assortment on hand. I might suffer withdrawal you know.
 

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Sounds like there is a little wear between seat and valve. It doesn't sound excessive to me. If the wear rate continues at this rate the exhaust clearances may have closed to be significantly tighter than recommended specs if you use the same service interval. Watercooled engines are much more temperature stable than air cooled so its less likely to burn a valve with a very high "spike" in engine temp and clearance closure. However a worst case is for extremely high engine temp coupled with inadequate clearance. Excessive or reduced clearances also affect valve timing. Exhaust valve surfaces and seats ajar at the wrong part of the engine cycle can be exposed to very high temps - not good.

You could probably get another 10,000miles before clearances close into the risk zone but if you've got the engine exposed and open to check the clearances why not do the adjustment now. Peace of mind and confidence in your equipment is very important if you want to enjoy the ride and be fully free from nagging concerns about the engines integrity.

Cheers
Lenz
 

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You're two thirds of the way there, so may as well do it now. The gaps are already outside spec and as lenz says they'll only deteriorate.

Look on the bright side, it's not the worst time of the year to be without the bike for a day or two, would be a lot worse in the summer.
 

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Discussion Starter · #5 ·
Thanks for the responses guys. That's the decision I had come to as well, what with all the rain we've been having here lately in the PNW the riding hasn't been all that pleasant anyway.

That is until I came to the realization this morning when I woke up and was thinking back. And low and behold, my dyslexia had gotten me again. I had switch the exhaust and intake positions in my head and in fact the clearances were spot on. Intakes at .006" and exhausts at .008". Both in the tolarance range. So back together again tonight. Maybe they'll need something at the 78K service, but for now they're good. Sorry for the false alarm.
 

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Yes its a problem when you can't see properly until you turn your hearing aid on.

I have found with checking clearances on multiple cyl valve gear that its worth using a sketch to make sure all the data goes to the right place. A simple clearance measurement and note on the existing shim thickness is very quick, helps with security of location / orientation and if engine temp is raised reduces the temp difference effects between start to finish. A sketch is a great source of engine history for future work.

Cheers
Lenz
 
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