Valve Adjustment - Kawasaki Motorcycle Forums
 
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post #1 of 5 (permalink) Old 01-18-2009, 08:13 PM Thread Starter
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Valve Adjustment

I have a 2007 Vulcan 900 Classic LT with 7200 plus miles. My question for anyone who knows for sure is, when or even why should you have to adjust valves on a motorcycle, when if you buy a new automobile you never have to worry about that. What are the signs that would let you know that the bike needs a valve adjustment? Would appreciate anyone's honest and knowledgeable answer. Thx
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post #2 of 5 (permalink) Old 01-18-2009, 08:20 PM
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Most cages have hydraulic lifters. Some bikes do as well, including the Vulcan 1500/1600. They are self-adjusting.

As engines age, the valves recede into the seats in the head. Another problem that is relatively uncommon is the valve stem will stretch (and it WILL fail if this is happening... but regular checks will reveal one valve closing tolerances faster than the rest and give you a clue to a potential problem).

As the valves recede, this closes the clearance, until eventually the valve does not completely close. This results in the valve not sealing, resulting in backfire through either the intake or exhaust, loss of power, and burned valves. This is particularly bad for exhaust valves. This valve has the hot exhaust passing it when it is open, and it is cooled ONLY by it's contact with the seat and head. It is rare for an intake valve to burn, but it can happen.

The US spec for the 900 is to check the valves every 15,000 miles. The AUS spec is every 26,000 miles. Different bikes are different... my 1981 CB750 specs a check every 7,000... at 12,000, two are toward the bottom of tolerance but are okay for another 7,000 or more.

Signs that it needs an adjustment?
It's too quiet.
Seriously... by the time you are showing symptoms, you are far beyond the need for a "check" and are potentially already looking at the need for a valve job.

- Rich
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post #3 of 5 (permalink) Old 01-18-2009, 08:31 PM
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Many cars do, in fact, require valve adjustments. And I'm not just referring to high performance cars or exotics...even something as mundane as a Honda CRV requires valve adjustments. Just depends on the car in question. As rich said...if it has hydraulic lifters...it wont need constant adjustment. But the 900 does not...so it does need constant adjustment.
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post #4 of 5 (permalink) Old 01-18-2009, 09:07 PM Thread Starter
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Does the way you ride( ie hard high rev or babying it) have anything to do with how often you should check them? And what is normal cost to have them checked?
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post #5 of 5 (permalink) Old 01-18-2009, 09:42 PM
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900 isn't hard to do.
Pull the tank, remove the plugs, pull the rocker covers, rotate the engine to TDC, and check the clearances.
If they're tight, slide the rocker arm to the side, remove the shim, and replace with a thinner shim (yes, this needs to be calculated, the service manual has all of the details).

Always calculate based on a target clearance in the middle of spec. If a shim is not available that will put you there, then use a shim that will put you on the high side of spec.

High RPM operation will increase wear, but so will increased cylinder temperatures caused by "short shifting" and lugging the engine. Factory recommended check intervals take this into account and it is unlikely that you'll go out of spec before 15k unless it's a track bike.

To have it done? Probably $300 to $500 depending on your dealer. Doing it yourself, an afternoon and the shims are about $5 each.

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