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What are some early signs you will hear/see on your bike that will notify you that your bike may need a valve adjustment soon?
 

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Dunno really - I've always just done it by the maintenance schedule so, they've never gone out of spec. I imagine that you'd hear some valve noise and may loose a tiny bit of power. If you ignored it long enough it could get ugly - if they were really loose they could come into contact with the piston and if they got really tight you could burn 'em. Either way it gets pricey fast.
 

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Well, it depends on whether the valve clearances on your bike tighten or loosen over time.

On a Ninja 250, for example, the valve clearances tighten over time. So some early symptoms of this are: engine hard to start, excessive knocking noises, lack of power at the bottom end. If the clearances are way too tight, you run the risk of head damage (eroding valve seats/guides e.g.), maybe even allow the valves to touch the top of the pistons if the piston-to-valve clearance is tight?

On bikes where the clearances loosen over time, I would imagine these would be early symptoms: excessive valvetrain noises, lack of power on the top end.

If the clearances are too loose, the cam lobes will not be putting enough pressure on the valves, thereby not opening the valves far enough. Conversely, if the clearances are too tight, then the cam lobes are putting too much pressure on the valves, thereby opening the valves too much.

On my Ninja 250, before I adjusted the valve clearances, my bike was very hard to start. I would have to apply full choke to start the bike, and I would have to leave the choke on until the bike "warmed up". When I checked the valve clearances, they were all too tight. After adjusting the clearances toward the looser end of the spectrum, my bike now starts with partial choke, and I can almost immediately turn the choke off after it has started. Now, instead of hard knocking sounds, the engine makes a nice sewing-machine-like ticks.

Anyway, this is probably more than you wanted to know!
 

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by the time you can "hear" a difference, it's already too late. Joel is dead on with the $$$$ line.

Just check em every 6k miles with a feeler guage. If you aren't sure when they were last done, check em anyways.
 

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BMW-K said:
by the time you can "hear" a difference, it's already too late. Joel is dead on with the $$$$ line.

Just check em every 6k miles with a feeler guage. If you aren't sure when they were last done, check em anyways.
How hard is it to do? Do you really have to tear into the engine to get to the valves?

I have a service manual for my 9R, and was thinking about doing my own valve adjustment. :confused
 

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I've never done it on a 9R, but i have on a ZX-11 many times. The biggest difference is the cams have to come out on the 9R, where the 11 has a rocker arm setup. You can look in the KB for my writeup on the 11.

If you've never done a valve adjustment before, I'd recommend you study the factory service manual pretty carefully before you start turning wrenches, then give yourself a whole day to spend with the bike.

It's really not all that hard though. Once you've done it a few times your time will come down dramatically, and you'll have a real sense of accomplishment. Plus you'll know the job was done right.
 

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What Joe Cool said! It's pretty easy if you can follow the directions in the service manual & use a feeler gauge. I think my first one ever took me a morning but, now it takes me longer to take the body work off.

Shim are kinda of a PITA 'cause after you measure all the clearances and figure out what size shims you need you have to run down to your local motorcycle shop to trade/buy the shims you need. Head home put 'em in realize you miss measured one and head back to the shop, etc. That's one fo the reasons threaded valve height adjusters get bonus points when I picking out a bike.
 

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rick said:
That's one fo the reasons threaded valve height adjusters get bonus points when I picking out a bike.
What bikes have this feature?

Newbie question: Why do you have to adjust the valves on bikes? I've never heard of this on cars.
 

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Paradigm said:
What bikes have this feature?

Newbie question: Why do you have to adjust the valves on bikes? I've never heard of this on cars.
Good question! :thumb

:confused
 

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www.google.com

search for the following:

desmodromic
"shim under bucket"
"screw type valve adjuster"

It's all out on the web and is better explained than I could.
 

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Paradigm said:
What bikes have this feature?

Newbie question: Why do you have to adjust the valves on bikes? I've never heard of this on cars.
The maitnance intervals are usually longer (~25kish), but you do have to adjust vlaves on many cars.

OTOH, some cars have what are known as hydralic lifters. These "inflate" with oil pressure to maintain proper valve clearances. My '83 Toyota Supra was setup this way. The Honda Nighthawk 750 is also setup this way, and it makes a great commuter/tournig bike for just this reason. Change the oil, filter, chain/sprokets, tires and brakes, and you'll have a 100k+ bike easy.
 

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Valve chatter or loss of performance are the signs. increased valve end clearence will decrease Cam duration and valve lift Causing loss of upper RPM effciency. Basically changing your cam timing out of the range your cylinder head is designed to Flow.

Chris
 
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