Valve clearances

2138 Views 10 Replies 9 Participants Last post by allwalk, Jan 18, 2005

allwalk

Discussion Starter · Jan 16, 2005

As you all know I am currently working on a How To for the tappet inspection. Well I am glad to say that it has been completed, the inspection that is. All I have to do tommorrow is download and edit the pictures and prepare the written material.

First off let me say the more I take this machine apart the more impressed I am with it

I won't reveal my clearance findings here right now because I want to ask a couple of questions.
1) In the Shim under bucket configuration do the clearances tighten up with wear or loosen up? I think as the valve seat wears or the seat on the valve wears the tolerances would tend to tighten up. What do you folks know or think?

When given the tolerances for the exhaust valves @ 0.008"-0.012" , it would be better to have the readings near the larger end. Yes? No?

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billmeek

· #2 · Jan 16, 2005

As the valves seat they tighten up a bit don't they???

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pauljo

· #3 · Jan 16, 2005

I've always been told that they tighten up with wear, and therefore you would want to set them toward the "loose" end of the tolerance range.

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Monterey10

· #4 · Jan 16, 2005

stretch

I've heard that in some engines, the valve stems will stretch, thus tightening up the valves. I'm not sure if that would apply to the Burgie engine.

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NormanB

· #5 · Jan 16, 2005

Hi Allan
I note in the manual that if adjustment is required the cam shaft has to be lifted. But I do know of other bikes where the shim can be 'jiggled' out using a special tool. OR is that only applicable to 'shim over bucket' designs?

Looking forward to the full report!

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ted clement

· #6 · Jan 16, 2005

Allwalk, the valves on 400's definitely tighten up as they seat in. Don't see why the 650 should be any diff. And I would adjust them to the higher number, that is making them slightly loose, so that there would be room for any future tightening and you would still be within tolerance.

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dero

· #7 · Jan 16, 2005

Removed

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allwalk

Discussion Starter · #8 · Jan 16, 2005

Hey guys thanks for the quick responses. You've all basically confirmed my thoughts as well.

Norm , In order to adjust the tolerances on the 650 shin bucket design, you most definetely have to remove the cam. Pictures and report should be up some time today.

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lilleyen

· #9 · Jan 16, 2005

allwalk said:
Hey guys thanks for the quick responses. You've all basically confirmed my thoughts as well.

Norm , In order to adjust the tolerances on the 650 shin bucket design, you most definetely have to remove the cam. Pictures and report should be up some time today.

Remove the cam :shock:

Rrrrrgghh, shudder :?

I just hope I can change my own oil and plugs when the time comes.

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Timothy Ma

· #10 · Jan 17, 2005

Thats a good question....I think the valves would tighten. Let me give you my reasoning and just state from past experience, from owning over 35 bikes that everytime I've done valves clearances, they have tightened.

This all relates to the valves seating in their seats. As you can imagine with the closing and opening of the valves (billions of times), its the outer rim of the valve seat (angled equal to it's seat face) and their corresponding seats that will eventually wear and therefore the valve with climb into the seat and further up into the cylinder head.

Also the material that is used for the shims, is a hardened material and unlikely to wear. The camshaft has a similar treated surface hardening that will result in a durable camshaft lobe.

When I did a valve check on a GS450GA Suzuki, the valves were all tight (previous owner never checked them) and when I removed the shims and measured them, they measured exactly to what was stamped on each shim. Upon close examination, the surface was smooth. Also, when the engine is turning over, the camshaft lobe does not hit in the center of each shim. This actually rotates the shim so if there is wear its distributed over the whole face of the shim.

Now for the 650 Burgman, I would suppose the shims are quite small and also have a stamp on them. Their should be a chart in the workshop manual to help you decide on shim replacement.

Good luck with your job and thank you for sharing this with us. I'm going to pick a 650 this March and like you, I like doing my own work. I was wondering if you have access to a bunch of shims. I know for the older GS series, you could purchase a full kit included a special tool (not the same for the bucket under shim) that had the rull range of shims.

Just some advice, keep a detailed record of the measurements and shim sizing used. Timothy

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allwalk

Discussion Starter · #11 · Jan 18, 2005

Hi Tim and thanks for your response . I use to build gokart racing engines and know exactly the wear you are talking about. I was pretty sure about what I thought but questions never hurt.

No I don't have access to a shim set. I didn't require one so I never ordered one. The Suzuki Tappet shim set # is 12800-05820 . The service manual also has an excellent chart telling you exactly what shims to use as long as you know your clearance and the # stamped on the bottomside of the existing shim.

By the way my right up with pics is complete in the how to section. A heck here is a shameless link to said topic http://burgmanusa.com/forums/viewtopic.php?t=3442&highlight=

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