[golferab05]

I just purchased a 2007 CRF450R and I'm trying to check the valve clearance. The exhaust valves check good, but the intake are so tight I can't get any of the feeler gauges into them. My question is if anyone has any idea of where I should start with shimming? And secondly, with how much force should I be using to get the feeler gauge to slide in?

Thanks,
Adam

[JimDirt]

Welcome to the site !!

Well you have a few issues here , if you have the HotCams Shim Kit , then start with a 1.75 and go from there , if that does not fit you will have to keep dropping sizes till you get to the right one , you will know when it slides in with a slight resistance , but not forcefully , if you get down to a 1.20 and its tight or still does not fit , then you are done and have to either replace the head or valves , since 1.20 is the smallest shim available

Now the issues:

If its that tight then the valves are on their way out , and its only a matter of time (a very short time/hours) that they go completely , or if you get to 1.20 then they are done , and your done riding till its fixed

Then you will have to decide (depending on your budget) on what you want to do , do you want to replace the valves with Titanium ?? , or Stainless ?? , the cost difference is minimal , but the cost can be anywhere from $200 to $1000 depending on if you do the majority of the work (except machine work) , or if your paying a shop to do it all(the latter is where the expense lies) , the major cost will be the seat cutting and any replacement parts needed to do the job correctly , depending on how worn the head is you may consider just replacing the head with a already done unit , ready to bolt back on ($500-$600 on up)

The options are plentiful , depending on your budget and needs , Ken (the owner here) does great work at competitive prices http://www.crfsonly.com/catalog/index.php/cPath/258 , or you can go locally or to one of the "big" companies like Pro Circuit , but be prepared to just hand them your wallet and the quality will be no better than what Ken does here , you will be paying for the name with them , its all dependent on your budget and what you want to do , but the bottom line is , once the valves start to move then its only a matter of time , for most people around here , we usually go with Stainless , they will last far longer than the Titanium , although with some of the specialty stuff , the Titanium can last much longer than before

Hope that helped some (though probably not what you wanted to hear)

[crfsonly]

Welcome to the site. Jim is correct. Once the valves start to tighten you have no choice but to have the valve seats professionally cut and new valves installed. Shimming them to clearance now will only yield a few engine hours before they tighten up again.

As for PC results being as good as ours, well to cut the seats they use a Serdi CNC machine and we use a NEWEN CNC machine. Anyone with a Serdi wishes they had a NEWEN.

Ken

[golferab05]

Thank you so much @JimDirt and @crfsonly! That was exactly what I needed and I appreciate all the valuable knowledge. I have the Hot Cams Shim Kit in route and we'll see what I find once I start that process.

But what I hear is that the valves are on their way out, and it sounds like sooner rather than later. You mentioned just replacing the head, I looked at the units on here and couldn't tell, do they come complete with valves, or are they strictly the metal block? It sounds like after buying new valves, and having them installed, the cost is going to be almost as much as just buying one of the new heads(OEM, not one of the performance units), which seems like a lot less of a hassle.

Any more knowledge you're willing to share is welcome. Again I thank you guys immensely!

[crfsonly]

New heads can come as just the head alone or with our CNC seat work and new valves installed.

New head with our CNC performance seat work and new KW valves and springs installed:

http://www.crfsonly.com/catalog/product ... ts_id/3167

Ken

[golferab05]

I received the shim kit and was able to get the bike into limits using 1.20's, so I need to have the valves done ASAP.

However, after putting the cam shaft holder assembly back on, and re-installing the cam shaft sprocket and chain, when I attempt to turn the motor via the crankshaft, the chain and camshaft sprocket only rotate about 1/4 of a turn before stopping. After which I can continue to turn the crankshaft but nothing up top moves. I have feeling this shouldn't be the case?

Any help?

[JimDirt]

What was the procedure you did to remove and reinstall everything ?? (step by step so we can see if you missed or did anything to cause this)

Are you doing this using a Service Manual ??

[golferab05]

I was checking the valve clearance using the how to article from here, and then followed the procedures for the camshaft removal from cyclepedia, which are to:

1.verify TDC
2.release tension from cam shaft tensioner
3.remove camshaft sprocket bolts
4.remove camshaft sprocket, secure chain to prevent from dropping inside
5.remove camshaft holder bolts
6.remove camshaft holder assembly

I did the opposite to put it back together.

[JimDirt]

And your positive the Tensioner is holding correct ??

Are you sure you had ALL 3 timing marks aligned ?? the one on the flywheel (the little round plug on the ignition side) , the 2 notches on the cam sprocket (it would look like this - - ) , along withe the cam lobes facing about 2 o'clock looking at it from the ignition side , the marks on the Balancer gear and case on the clutch side behind the big round plug

The only things it could be is the chain hanging up , or the tensioner not working , or the timing is off , if those have been eliminated , the other and most likely possibility would be the shim itself popped out of the recessed part on top of the valve stem when you lifted the cam tower again , and is holding the bucket up , which would lock everything up like your describing , this would be my first guess if the tensioner and timing is correct , that is about all that could make the engine lock up

[golferab05]

Thanks JimDirt, I'll double check everything and see what happens.

I really appreciate the help!

[golferab05]

Does anyone know if the decompressor shaft (located in the camshaft) only be installed in one (the right) position?

[golferab05]

I went through and verified the intake shims were seated properly, motor was TDC, reinstalled the cam assembly with lobes at 2 oclock (towards back of bike), and the cam sprocket marks were level. The when I try to turn the crank arm, the motor and cam shaft turn approximately 1/4 of a turn (till the lobes are straight up), at which point the crank will continue to turn, and the cam and chain no longer turn.

Could the chain be coming off the crank at the bottom?

Timing was mentioned earlier, could this be an issue?

[JimDirt]

I the chain is off the bottom , that would mean the chain stop is bent and the chain is off the crank gear , the only way to confirm this would be to remove the chain from the top and hold tension on it , and slowly rotate the engine by hand using the chain to move it , if its off the chain will not move the crank , and the engine will still not turn over , this will eliminate any timing issue , since if the cam is disconnected , the only thing moving will be the crank and tranny gears

If the crank does not move back and forth exactly as the chain does , then your only option would be to remove the ignition cover and see if you can get behind the flywheel to get it back on , otherwise you will have to pull the flywheel , do not pull the flywheel unless you have the correct flywheel puller , otherwise , you will ruin the end of the crank and then its new crank time , but that test should tell you if the chain is attached or not , remember , holding the chain and holding tension on it , you will feel if its attached to the gears , and it will move the crank exactly as your moving the chain back and forth ....follow ??

[JimDirt]

Here is how the de-compressor is assembled

[mossman77]

Sounds like the chain came off the crank. Happened to me when I was shimming my bro-in-law's 250R. Pulled off the left cover and put it back on the gear. No need to pull the flywheel, at least on the 250R. Not sure about the 450R. I wouldn't think so. You'll want to replace the gasket, so order one of those asap.