camshaft chain replacement,pulling the trigger


26 replies to this topic
  • tom n

Posted March 07, 2011 - 05:21 PM

#21

I'm not sure I follow you? I was under the impression that if there is wear to anything then this would cause a TOO much gap situation?? So if I understand you correctly I would need to DECREASE the size of the shim under the ( Isn't it called a bucket?). What is the size of the stock shim? I'll look the manual over and I already looked over greyracers sticky and there is no mention of decreasing the gap. Also, how far can you go until new valves,etc. need to be put in the head? The things I didn't know.... Anyway thanks in advance again, Tom

  • KJ790

Posted March 07, 2011 - 07:27 PM

#22

I'm not sure I follow you? I was under the impression that if there is wear to anything then this would cause a TOO much gap situation?? So if I understand you correctly I would need to DECREASE the size of the shim under the ( Isn't it called a bucket?). What is the size of the stock shim? I'll look the manual over and I already looked over greyracers sticky and there is no mention of decreasing the gap. Also, how far can you go until new valves,etc. need to be put in the head? The things I didn't know.... Anyway thanks in advance again, Tom


Nope, as the valves wear the clearance gets smaller, so you need to decrease the size of the shims to keep the correct clearance. There is no such thing as a stock sized shim, they all come with different sizes from the factory. Due to machining tolerances it takes different size shims to get each valve in spec when the bike is new. Most new bikes tend to come with shims between a 170-190 though. I don't like to reshim more than once on a set of valves, so once they tighten up the first time I reshim them, then when they tighten up again I replace them. Running them beyond that point is a gamble as the face of the valves is getting pretty thin at that point. Once the valves have tightened the first time, they will tighten up again quickly after reshimming them because the hard surface coating on the valve has been worn off, so the soft titanium is now contacting the seat, allowing the valve to wear much quicker than when the valve was new.

  • CaptainKnobby

Posted March 07, 2011 - 07:59 PM

#23

After the coating on the valves wear is that when the valve head starts pounding into the valve seat? I guess that is when you have to have the valve seats laped Right?

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  • Mr. Neutron

Posted March 07, 2011 - 08:08 PM

#24

Someone please correct me if I'm wrong, but I don't think you lap titanium valves (if that's what you have in your bike....). The hardened coating that ti valves have will basically wear away when lapped, and leave a softer material to take the pounding that valves get subjected to......

Jimmie

Edited by Diesel Goober, March 07, 2011 - 08:08 PM.
poor proofreading......


  • KJ790

Posted March 07, 2011 - 09:33 PM

#25

Someone please correct me if I'm wrong, but I don't think you lap titanium valves (if that's what you have in your bike....). The hardened coating that ti valves have will basically wear away when lapped, and leave a softer material to take the pounding that valves get subjected to......

Jimmie


Exactly. Never lap titanium valves, just have the seats cut by a professional and drop in the new valves.

  • grayracer513

Posted March 08, 2011 - 11:22 AM

#26

What's been posted is correct. When the valves close, they move up toward the cams, right? As metal is worn off the valve sealing face and the valve seat, it goes up farther, and the clearance is less. Once a valve has needed a shim two sizes smaller (.10mm) than the original one used, it needs to be replaced.

And no, you NEVER ever lap Ti valves.

  • tom n

Posted March 08, 2011 - 01:06 PM

#27

Thanks for the wealth of knowledge on this thread! I'll go ahead and post a new topic on valves etc. Since this thread was started on cam chain replacement. I'm also not the kinda guy to just take take take without helping others if I can so i'll lurk alittle.... I do have a few more ques. on reshimming before I tackle that so if you dont mind...... thanks all in advance, Tom





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