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07' CRF450r Decompression Arm Clearance

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Excuse the ignorance as I'm from the "blue" camp, but my buddy tore down an 07' CRF450r and we're having trouble figuring out the .025" clearance for the decompression arm. Where and how do we measure this? The intake side was easy, but this damn sprung arm has us banging our heads on the wall. With everything all set at TDC, the intake side is good. Should we be able to get an .011" feeler gauge on the exhaust valves, and a .014" at the lobe side of the arm? We don't have any manuals, so the the whole deal has got us a bit confused to say the least.

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The 07 has a different style decomp mechanism. You dont need to check/adjust it. I didnt know this when I bought my 07 and it was really hard to start. I took the valve cover off and thought a piece was missing because at the time I didnt know in 07 they changed the decomp. Just make sure the exhaust valves have .011 between the rocker arm and the valves. On the sprocket side of the cam you will see a small weight with a spring hooked to it. There is a rod inside the cam hooked to that weight, and on the other end that rod goes into a dowel which you can see sticking out of the exhaust cam lobe. The small amount it sticks out of the lobe is enough to open the exhaust valves while kickstarting it. Once the engine starts the centrifigal force from the cam spinning fast will shift that spring loaded weight and retract the dowl back into the cam.

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there is no adjusting the 07+ decomp. check the sticky about timing the bike at the top of the forum for pics

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So what do I tell my mechanic? Is he supposed to set a clearance at TDC with the decompression arm engaged. That sounds stupid, if i read the other posts, the decompressor is always engaged and the exhaust valves are open to allow the kickstart. someone please clarify...

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tell your mechanic to get a manual and learn what he/she is working on. Personally pick up the bike and take it to someone that knows what they are doing. Or learn yourself.

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So what do I tell my mechanic? Is he supposed to set a clearance at TDC with the decompression arm engaged. That sounds stupid, if i read the other posts, the decompressor is always engaged and the exhaust valves are open to allow the kickstart. someone please clarify...

Again, did you read the 07+ bikes do NOT have an decompression arm or adjustment. It is a weighted style decompression system now like the other brand bikes. Look at the sticky to time your bike for pics.

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actually adjusting the clearance on the exhaust valve will increase or decrease the amount the decompression opens the valve when kicking. deal with this all the time, when youre putting 14:1 compression in a 450, you gotta figure out how to make it easier to kick. but if youre just doing an OEM rebuild(stock compression, cam timing etc.) then set your exhaust valves at .011 and run it.

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I put this up a couple weeks ago regarding the decompression adjustment or lack thereof of an 07 450r. My mechanic adjusted my valves and they are perfect at TDC. The bike has a super hard spot that makes me think the decompression function isnt working. The decompression spring and cam projection are working, just cant figure out why it is so much harder to kick. I know he is missing something. Any ideas

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