Hard to kick (issue with decompression?)

[mx473]

I have posted the following in the CRF450 forum, but since there are some very knowledgeable people in the CRF250 forum (Charlie comes to mind:smirk:), I double post.

I have a 2004 CRF 450 that was always easy to start until the valves zero'd out. I put SS kibblewhite, and I also re-ring my Wiseco piston. I also "played" with the decompressor arm clearance, but made sure that I was eventually in spec (0.011 + 0.014) ... The bike fired up first kick BUT the compression is WAY higher than it was before. It almost looks like the decompression is not working. Is it due to the stronger KB springs, new rings on the piston, did I mess up somehow the decompressor arm clearance ???

[Charlie C]

It's not hard to set the decompression on the 450's so I doubt that you did something wrong with the set up, unless the cam gear was in the wrong spot. The 450's run forever with low compression and you hardly notice the difference in the power because it's so extreme. So when you installed the new components, I'm sure that was a giant compression boost. Just make sure that the decompression spring isn't broke. If it is, that will drastically increase the compression on starting.

[mx473]

Charlie, thanks for your valuable suggestion (as usual:smirk:), I'll check that spring.

[tagmetals]

I have a issue with my 07 crf 450. One of the cam chain bolts came loose from the sprocket. It was just luck it did not fall down in the crank case. I took it to a mechanic and he told me the de compression spring was broken. I ended up having to buy the sproket and decompression assy since this year of bike they cannot be bought seperatly. Ive got the bike back and i have to wait until i get just past TDC before i can kick it over. This guy is telling me this is normal. The bike will start on the first or second kick once i get past TDC. everything turns over just fine when the plug is out. Timing is good as well. Does anyone have anything that would help me eliminate this hard starting issue?. Thanks in advance. JR

[Grinstead_77G]

Listen for the decompression lever "click" when going past TDC. This will at least give you some feedback to indicate the decompression lever's lobe is lifting the exhaust valves.

I have had a few decompression lever pivots on CRF cams bind up due to the end flat spring being bent, and the pivot gets bound up with the decompression lever lobe in the retracted position. If you are not hearing the decomp system click, remove the cam cover and make sure the decomp shaft turns freely in the cam and check to see if the wire return spring is intact. In the non-running position, the decompression counterweight should be held in by the wire spring rotating the decompression lobe into position to slightly lift the exhaust valves. When the engine starts, centrifugal force from the spinning camshaft causes the counter balance to swing out and rotate the decompressor to retract the decompression shaft lobe into the camshaft so the exhaust valves close properly.

[tagmetals]

Hey, thanks for the great response. Well said. I actually had the the valve cover off today and decided to put it back together and say the hell with it as the cycle runs just fine. I have heard that this year is known for this issue. Have you hear of this? Now having said that and hearing your response, i will dis assemble and follow your instructions as i did not hear the noise you are referring too. I did notice the spring is in tack and the detent pin seemed to be working but did not pay that close of attention. Once again i appreciate all of your feedback. With your help i know i will get through this, JR.