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Discussion Starter #1
I am considering buying the GYTR headgasket and the Graves cam sprokets. Has anyone done this that may could perpare me for any surprises. The other thing is since I'll have the head off I figure I could do a little machine work, any areas that need particular attention?
 

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check, check, and re check your valve clearances. The tolerances are so tight right now, you can only drop about .1mm without breaking something at 215*F

a lot of time on the dyno if you're going to be degreeing your cams.

Look into the GYTR cam sprockets, they are designed already for several different degree combos that are impossible to screw up.
 

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Discussion Starter #3
If the GYTR sprockets are set-up for particular degree angles, how would i know which ones would be best for the motor? I guess what i mean is the Graves sprockets seem like they would be a much easier to adjust. In either case I am alot more familiar with the slotted design. I have built tons of car engines, but this is going to be my first bike engine, so all the insight i get is welcome.
 

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Och-

I can only find Yamaha sprockets made for racing which degree the cams at 103 intake/112 exhaust. You made it sound like the ones you are talking about have several degree options. Are these not the sprockets you are talking about?

Where do you buy the ones you are talking about?

On a semirelated note if you install the skinniest head gasket, how critical does that make piston to valve clearance with stock cams?

Matt
 

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Look over the SS Race Kit Manual (Located in the Maint. and Tech), it explains the cam sprockets and how you can adjust them up to 5 different settings.

It also lists all the ‘Race’ specs for the engine, and clearances that need to be maintained.

With my experience, I dropped my head gasket from .6mm to .4mm and snapped a valve, after it warmed up. I did not measure because I was under the impression it would be fine. When I tore into it again I measured and found I was really only comfortable dropping .05mm.

In the past I also did some calculations on the expansion coefficients of the valves, and piston, and deducted that the most you could remove is about .1~.15mm without running into problems.

I am hoping to tear into an engine very soon, and spend a lot of time looking over everything and doing some R & D on it for sportbikehowto.com.

The compression gains that can be made with this engine will only come if you machine the head and reduce the area piston compresses into. A squish height of .6mm is needed at all times. This happens to be the size of the stock gasket, and the piston does not come up to the top of the case, so you can safely reduce the gasket by the distance from the top part of the piston and the case. In the case of my ’99 motor just over .05mm.
 

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YamRZ350 said:
Did you leave the cam timing stock when you installed the kit head gasket and broke a valve?
yes.

D, you going to let me tear into your 06 if we come up?

On a side note, there are some guys on here that said they've been able to machine both the case and the head, and still install a .4mm gasket. But the math doesn't add up, and until it does, I don't believe them.
 

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ochlocracy said:
yes.

D, you going to let me tear into your 06 if we come up?

On a side note, there are some guys on here that said they've been able to machine both the case and the head, and still install a .4mm gasket. But the math doesn't add up, and until it does, I don't believe them.
Do you have all the measurements?
 

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Discussion Starter #11
ochlocracy The compression gains that can be made with this engine will only come if you machine the head and reduce the area piston compresses into. A squish height of .6mm is needed at all times. This happens to be the size of the stock gasket said:
I am confused, I would assume that machining the head and using a thinner head gasket would provide the the same thing, an increase in compression. Because the thicker head gasket would act as more distance between the valves and head, as would the "excess" head material. Now I can understand how machining the head will have a direct effect on the size of the combustion chamber in the head. But then if I reshaped the combustion chamber to suit then I would defeat the purpose of shaving the head. Right? Please someone point me in the right direction.
 

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ochlocracy said:
yes.

D, you going to let me tear into your 06 if we come up?

On a side note, there are some guys on here that said they've been able to machine both the case and the head, and still install a .4mm gasket. But the math doesn't add up, and until it does, I don't believe them.
I asked because (as you probably already know) you can run into piston to valve clearance problems with altered cam timing before and after TDC, when the piston to head clearance is good at TDC.

There is a guy selling a 1st. generation head in the race/track day section here that says there is .025" taken off of it! (And he says he raced it that way).
 
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