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shim selection

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First time I've had to change shims. AS rebuilt the head last summer and this is the first time I've checked them, about 25 hours on the rebuild. Intakes were REALLY tight, .002 and .004 but exhaust were both at .010. I've done the calcs for the shims I need but went to the local Honda shop and they did not have exactly what I needed. Do you guys usually measure in mm or convert from thousandths? First time I did it all in thousandths then converted to mm. Did it the other way around and results were about the same but I think this gives me a better "feel" for what I can get away with for shims. I really don't wan to buy the whole set of shims, this is the only stroker in my garage.

Feedback?

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Just get them as close as you can, I really doubt that any valves are precisely accurate.

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hasn't anyone done this themselves without buying the whole kit?

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Why waste your time using standard measurements. I use only metric. This way there is no bull s*** converting. Shims come in metric sizes so why not just use the metric numbers on the feeler guages. In my valve adjustments I will use the shims that put them at the top of spec range or what will make both the valves closest in clearence.

The problem with buying just one shim is sometimes your feeler measurement is not exact. Especially when the valves are slammed shut. Good luck to you.

Just my two cents

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hasn't anyone done this themselves without buying the whole kit?

I always buy them as needed.

Just do the equasion in MM.

A good set of feeler guages has both MM and IN marked on it those make it easy to do the calculations both ways if you want to.

A digital caliper that measures in MM is a great thing to have.

Part of the calculation is nowing the existing thickness, figure out how big of gap (clearance)you want to have and then choose a new size shim that will get you the closest, its that simple.

Your local shop should have shims individual, take your caliper to double check at the shop.

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I always buy them as needed.

Just do the equasion in MM.

A good set of feeler guages has both MM and IN marked on it those make it easy to do the calculations both ways if you want to.

A digital caliper that measures in MM is a great thing to have.

Part of the calculation is nowing the existing thickness, figure out how big of gap (clearance)you want to have and then choose a new size shim that will get you the closest, its that simple.

Your local shop should have shims individual, take your caliper to double check at the shop.

thanks, I'm going to Harbor Freight on the way home to pick up a digital caliper that measures mm and inches. Only have an inch caliper now, that's why the OP. Once I can measure the existing shims in mm I'll confirm my calculations in mm. I can read the thickness on all but one shim, but checking them is a good idea as mentioned. Will err on the "loose" side to be sure, loose is always safer than tight.

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thanks, I'm going to Harbor Freight on the way home to pick up a digital caliper that measures mm and inches. Only have an inch caliper now, that's why the OP. Once I can measure the existing shims in mm I'll confirm my calculations in mm. I can read the thickness on all but one shim, but checking them is a good idea as mentioned. Will err on the "loose" side to be sure, loose is always safer than tight.

.04 IN and .06 EX is the way:thumbsup:

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.04 IN and .06 EX is the way:thumbsup:

Assume you meant to say .004 & .006 right?

Never thought I'd say too tight but that does sound a bit close doesn't it? Spec. is .006 intake and .011 exhaust.

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Assume you meant to say .004 & .006 right?

Never thought I'd say too tight but that does sound a bit close doesn't it? Spec. is .006 intake and .011 exhaust.

Yes I meant .004 and .006....Its tight its right:thumbsup:

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Going all metric was the way to go. picked up a digital caliper from Harbor Freight that measures in. and mm. Went back through the calcs. in mm. then went to Honda and they had ones that were close, erred on the loose side (sorry Kanyonkritter!) to be safe. Buttoned it all back up and exhausts are right at .011 and intakes are at .008.

Thanks again for your suggestions.

But my god, $10.00 per shim!!!! And that was with an AMA "discount" Next time I bite the bullet and buy the kit, will pay for itself in a couple of uses. Where else can you buy the individual shims? How do you replenish the kits' used shims?

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:banana:

erred on the loose side (sorry Kanyonkritter!) to be safe. Buttoned it all back up and exhausts are right at .011 and intakes are at .008.

Dont apologize to me....apologize to your bike. If you ever want to know why tighter is better I will explain the mechanics behind it:thumbsup:

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Going all metric was the way to go. picked up a digital caliper from Harbor Freight that measures in. and mm. Went back through the calcs. in mm. then went to Honda and they had ones that were close, erred on the loose side (sorry Kanyonkritter!) to be safe. Buttoned it all back up and exhausts are right at .011 and intakes are at .008.

Thanks again for your suggestions.

But my god, $10.00 per shim!!!! And that was with an AMA "discount" Next time I bite the bullet and buy the kit, will pay for itself in a couple of uses. Where else can you buy the individual shims? How do you replenish the kits' used shims?

Unless you are doing multiple bikes you should never need to replentish the kit. As I recall the kit had four of each size shim. Plus the ones you pull out can be put into the kit. If the numbers are worn off mic it with your caliper and place it accordingly.

Glad to hear you got it all taken care of.:banana:

Kanyonkritter I would like to hear the mechanics behind it. I am always interested in new-different information.

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Kanyonkritter I would like to hear the mechanics behind it. I am always interested in new-different information.

The way that it has been explained to me is that the valve will follow the contour of the cam longer, hence the cam "sets" the valve down into the seat rather than the valve snapping closed from the valve spring psi.....At first I thought the notion of running a tighter clearance was ludacriss I am a "go by the manufactures numbers" kinda guy but when it was explained to me like this it made alot of sense. I ened up getting damn near 500 hrs. on my stock valves. Unlike most I was so happy with the OEM's that I put OEM's back in when the motor was rebuilt. Round 2:ride: BTW for what its worth I hold an A&P certificate and was a profesional aircraft wrench for several years.

Edited by kanyonkritter

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