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Discussion Starter · #1 ·
So I rebuilt my engine completely. Everything besides cases gears and cam replaced. I'm having trouble figuring out which size shims I should put in it to start with. I have a 12:1 cp piston, full kibblewhite valvetrain and hrc cam and this is my first engine build. It had 1.20 intake shims in both intakes before I rebuilt it. Now I'm just confused on which size shims I should use for initial break in or whatever. I'm new to this so someone please help me so I dont destroy 4 grand lol
 

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First and foremost, do you have a service manual?
Do you understand what the purpose of the valve shim is and how it works?
I ask, not to be a prick, only to be able too explain the answer better or faster as needed.

When you say, "you rebuilt the engine completely", did you use the head that was on the bike before rebuild w/new KB valve train components?
Or,
Did you replace the head and the KB hardware was installed for you?
Or,
Did you replace the head and you installed the new KB hardware?
It makes a difference if you want the right answers, as I was where you are once, and like you said, you don't want to waist 4 G's.
Assuming everything else is correct in the motor I'd start around 2.40 exhaust and 1.75 intake. I came to these numbers by looking in my shim box inventory and picking the 2 biggest shim sizes that had been used previous to the rebuild. So if you have all new shit then you might need bigger shims than I mentioned above.

As the valve and valve seat face wear against each other from opening and closing, (valve stem stretch) this in turn doesn't allow the valves to open all the way up (tighten up) A smaller and smaller shim is needed to keep the clearances within tolerance, so if new valves are going in your old head the valve seats need to be cut to fit your KB hardware. If new KB hardware is used that hasn't had the valve seats cut yet or old head used with seats cut to match your new valves, these parameters, will all change what shims are needed be used.

My setup used to give you the above mentioned starting points was an 04' w/complete rebuild, 11.5 high comp. piston, new APE head (OEM valve sizes), HRC cam and HR stage II cam, +3 stroker crank (this wont effect pistons max height)

Let me know if you understand what I'm talking about or not, and if you do or do not need a service manual. Let me rephrase that, if you have or do not have a copy of the service manual, because you'll definitely need a copy to reference for this job.
 

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I always do what I call a "Blind install" I start off with a 1.95 shim on the intake and 1.95 shim on the exhaust after brand new valves have been installed (assuming you have new valves with fresh cut seats).


Now here is how I do it.
I first install the 1.95 Shims in all 4, then I install the cam tower (Note - With the intake lobes facing to the back)

At the same time the cam sprocket gear and timing chain disconnected.

Now Torque the cam tower down and then measure your clearances while holding the cam in the "TDC" position. (I say not to install the came chain and gear just so you don have to remove all this stuff again and again)

Next I draw a diagram down on a piece of paper with four circles in a valve and head diagram because you need to keep track of what valve shim went where (example - 1.50mm shim went on the left exhaust valve and 1.80mm shim went on the right exhaust valve) same for intake valves.

So if a 1.95mm shim in there and you have a .016" thousandths gap just convert 1.95mm into thousandths which is .076" thousandths and ad that measured .016" Thousandths which comes out to .092" Thousandths, now you wanna count back 11 which is the desired gap that you want and you will be at .081" Thousandths which gives you a 2.05 Valve Shim you will need in order to achive a .011" Gap for the exhaust.

(this measures the total distance from the valve stem to the cam buckets and or rocker arm and then you just deduct the gap you want)



I do apologize I'm not the best with math but this is what works for me and is easiest for me to do.
 

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2004 TRX450R
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I always do what I call a "Blind install" I start off with a 1.95 shim on the intake and 1.95 shim on the exhaust after brand new valves have been installed (assuming you have new valves with fresh cut seats).


Now here is how I do it.
I first install the 1.95 Shims in all 4, then I install the cam tower (Note - With the intake lobes facing to the back)

At the same time the cam sprocket gear and timing chain disconnected.

Now Torque the cam tower down and then measure your clearances while holding the cam in the "TDC" position. (I say not to install the came chain and gear just so you don have to remove all this stuff again and again)

Next I draw a diagram down on a piece of paper with four circles in a valve and head diagram because you need to keep track of what valve shim went where (example - 1.50mm shim went on the left exhaust valve and 1.80mm shim went on the right exhaust valve) same for intake valves.

So if a 1.95mm shim in there and you have a .016" thousandths gap just convert 1.95mm into thousandths which is .076" thousandths and ad that measured .016" Thousandths which comes out to .092" Thousandths, now you wanna count back 11 which is the desired gap that you want and you will be at .081" Thousandths which gives you a 2.05 Valve Shim you will need in order to achive a .011" Gap for the exhaust.

(this measures the total distance from the valve stem to the cam buckets and or rocker arm and then you just deduct the gap you want)



I do apologize I'm not the best with math but this is what works for me and is easiest for me to do.
Ryan94Wright definitely did a better job explaining the process
 

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Discussion Starter · #5 ·
First and foremost, do you have a service manual?
Do you understand what the purpose of the valve shim is and how it works?
I ask, not to be a prick, only to be able too explain the answer better or faster as needed.

When you say, "you rebuilt the engine completely", did you use the head that was on the bike before rebuild w/new KB valve train components?
Or,
Did you replace the head and the KB hardware was installed for you?
Or,
Did you replace the head and you installed the new KB hardware?
It makes a difference if you want the right answers, as I was where you are once, and like you said, you don't want to waist 4 G's.
Assuming everything else is correct in the motor I'd start around 2.40 exhaust and 1.75 intake. I came to these numbers by looking in my shim box inventory and picking the 2 biggest shim sizes that had been used previous to the rebuild. So if you have all new shit then you might need bigger shims than I mentioned above.

As the valve and valve seat face wear against each other from opening and closing, (valve stem stretch) this in turn doesn't allow the valves to open all the way up (tighten up) A smaller and smaller shim is needed to keep the clearances within tolerance, so if new valves are going in your old head the valve seats need to be cut to fit your KB hardware. If new KB hardware is used that hasn't had the valve seats cut yet or old head used with seats cut to match your new valves, these parameters, will all change what shims are needed be used.

My setup used to give you the above mentioned starting points was an 04' w/complete rebuild, 11.5 high comp. piston, new APE head (OEM valve sizes), HRC cam and HR stage II cam, +3 stroker crank (this wont effect pistons max height)

Let me know if you understand what I'm talking about or not, and if you do or do not need a service manual. Let me rephrase that, if you have or do not have a copy of the service manual, because you'll definitely need a copy to reference for this job.
Ok, so let me try to answer that all lol. I disassembled everything completely, head to crankshaft. Sent head to racers edge along with my new kw ss valves so he could cut the seats for the valves. I also have kibblewhite dual spring kit (30-30720 I'm pretty sure is the part number) and kw keepers and lifter buckets....EVERYTHING is new except the camshaft, which I was told by a trusted builder was an hrc cam. But I really dont think it is, but he did my valves before I rebuilt it. I assembled the head myself, assembled bottom end, new oem welded trued crank, 12:1 CP piston, cometic top end gasket...I'm fairly confident in my abilities I just dont know which shim to start with for adjustment...and yes, I have 2 service manuals, a hard copy of a clymer manual and an oem one on my phone.

Before I got new seats and valvetrain, there was 1.20 shims in the intake and I didnt measure the ones in the exhaust, but the exhaust ones were considerably thicker and the valves in considerably better condition than the intakes.

I understand everything, maybe just having a dumb moment and it's just not clicking in my head idk
 

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Discussion Starter · #6 ·
I always do what I call a "Blind install" I start off with a 1.95 shim on the intake and 1.95 shim on the exhaust after brand new valves have been installed (assuming you have new valves with fresh cut seats).


Now here is how I do it.
I first install the 1.95 Shims in all 4, then I install the cam tower (Note - With the intake lobes facing to the back)

At the same time the cam sprocket gear and timing chain disconnected.

Now Torque the cam tower down and then measure your clearances while holding the cam in the "TDC" position. (I say not to install the came chain and gear just so you don have to remove all this stuff again and again)

Next I draw a diagram down on a piece of paper with four circles in a valve and head diagram because you need to keep track of what valve shim went where (example - 1.50mm shim went on the left exhaust valve and 1.80mm shim went on the right exhaust valve) same for intake valves.

So if a 1.95mm shim in there and you have a .016" thousandths gap just convert 1.95mm into thousandths which is .076" thousandths and ad that measured .016" Thousandths which comes out to .092" Thousandths, now you wanna count back 11 which is the desired gap that you want and you will be at .081" Thousandths which gives you a 2.05 Valve Shim you will need in order to achive a .011" Gap for the exhaust.

(this measures the total distance from the valve stem to the cam buckets and or rocker arm and then you just deduct the gap you want)



I do apologize I'm not the best with math but this is what works for me and is easiest for me to do.
Hey you explained it very well my man thank you. I love this community on here lol

I've always wanted to do a project like this and never have cuz of money and now I can afford it but I can't afford it all over again a week after it's done haha
 

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Hey you explained it very well my man thank you. I love this community on here lol

I've always wanted to do a project like this and never have cuz of money and now I can afford it but I can't afford it all over again a week after it's done haha
Glad that you understood my comment lol.

How to tell an HRC cam vs Stock Cam is if you look towards the side of the cam that the decompression mechanism bolts to you will see either 2 Lines or 1 wide groove. If it's 2 Lines it's a OEM cam, if it's a wide groove it's aFirst Gen (04/05 HRC Cam)

Also I work at Racers Edge ironically, so I might have even been the one who did the bowl blending job on your head after it's been in the CNC machine haha 👍🏻
 

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How to tell an HRC cam vs Stock Cam is if you look towards the side of the cam that the decompression mechanism bolts to you will see either 2 Lines or 1 wide groove. If it's 2 Lines it's a OEM cam, if it's a wide groove it's aFirst Gen (04/05 HRC Cam)

Also I work at Racers Edge ironically, so I might have even been the one who did the bowl blending job on your head after it's been in the CNC machine haha 👍🏻
Actually, this is incorrect. A stock 04-05 cam has two grooves, Early HRC has three grooves. 06+ stock cam has no grooves (nor do the CRF cams), and the late HRC cam has one wide band or groove on it.

And yeah, sometimes setting lash on a fresh head can be a crapshoot. But usually if it’s a reputable shop they can tell you where a good starting point is. Otherwise, start small and work your way up lol
 

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Actually, this is incorrect. A stock 04-05 cam has two grooves, Early HRC has three grooves. 06+ stock cam has no grooves (nor do the CRF cams), and the late HRC cam has one wide band or groove on it.

And yeah, sometimes setting lash on a fresh head can be a crapshoot. But usually if it’s a reputable shop they can tell you where a good starting point is. Otherwise, start small and work your way up lol
Thank you. You're 100% Right on the cams.
 
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