Should I go up .001" on valve clearances as I've read in a couple threads here?

If it's broken or just needs tweaked

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juntjoo
Posts: 294
Joined: Fri Nov 10, 2017 6:19 pm

Should I go up .001" on valve clearances as I've read in a couple threads here?

Postby juntjoo » Tue Jan 01, 2019 8:45 pm

What's the consensus on this? The info I read by some on sohc.net was a bit too technical for me so I didn't quite understand it but the claim is that it increases the life of your valves, particularly the exhaust ones, that otherwise within a few k miles your valves could fail I think I read. Since I'm doing my valves now I'm considering taking this advise.

I think from my experience I will experience "clacking" from this. If I'm correct and do do this adjustment and get "clacking" should I go back to book spec?

And happy new year to ya'll
82" cb650 Nighthawk

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Volker_P
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Re: Should I go up .001" on valve clearances as I've read in a couple threads here?

Postby Volker_P » Wed Jan 09, 2019 5:11 am

There is no need or reason to deviate from book specs unless you really know what you do.
Special fuel or special cams might be a reason for things like that.

If somebody should run into valve overheat problems with book specs, this is probably due to too lean. And this is most probably due to pod filters on piston carbs without adequate rejetting. So I would not be too surprised if CB650 exhaust valves are reported in forums to be "susceptible". But I would not think this finding holds for stock airbox and carb systems though stock jetting is also already on the lean side.
Cosky's great (free) online manual: http://cosky0.tripod.com

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juntjoo
Posts: 294
Joined: Fri Nov 10, 2017 6:19 pm

Re: Should I go up .001" on valve clearances as I've read in a couple threads here?

Postby juntjoo » Wed Jan 09, 2019 5:17 am

Volker_P wrote:There is no need or reason to deviate from book specs unless you really know what you do.
Special fuel or special cams might be a reason for things like that.

If somebody should run into valve overheat problems with book specs, this is probably due to too lean. And this is most probably due to pod filters on piston carbs without adequate rejetting. So I would not be too surprised if CB650 exhaust valves are reported in forums to be "susceptible". But I would not think this finding holds for stock airbox and carb systems though stock jetting is also already on the lean side.


Thanks. I just went with book specs.
82" cb650 Nighthawk


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