04 YZ450 cam and valves..?

While I had the tank and seat and CDI box off, I decided to check my valves. Exhaust was in spec (.25 no go, .20 felt pretty good). Checked intake and got 0.08 for #1 (clutch side), 0.051 for #2, and 0.00 for #3. So I took off the intake cam and pulled #1 and #3 buckets off easy.. number 2 bucket wouldnt come out.. so I inspected around the ID of the bucket hole and noticed that there was some 'mushrooming?' from the cam journal on the clutch side. Took a razor blade and scraped that off best I could still wouldnt come out. I then decided to try a small screw driver.. so I scraped the mushroomed part a but more until it was close to flush. Bucket popped out after that. As I was looking at the cam journal where the mushrooming occured I noticed that there was no hole in the oil slot like on the other jounal. Is this normal or do I have a defective head thus causing this mushrooming effect. Checked the cam shaft and it is well within specs with hardly any wear. Will get plasti gages to check the clearance once its all put together.. but I'm worried about it because there is no oil weep hole. I'm worried I will have to buy a whole new head.. does everything seem OK to you guys?

That doesn't sound right to me, can you shoot some pictures so we can see for ourselves? It should be identical to the other bearing surfaces.

Josh

yeah I'll take some pics tonight.

I noticed that there was no hole in the oil slot like on the other jounal. Is this normal or do I have a defective head thus causing this mushrooming effect.
There is only one hole in the head at that point. Oil is fed up through that passage into the intake cap to a distribution manifold that oils the intake cam and bearing, and directs oil to a passage leading to the exhaust cam.

Wear in the cam bearing surfaces happens primarily it the cap, not the head, since the valve springs force the cams upward. The head, however, will certainly be damaged in the event that a cam should seize. In that event, EDCo can fix it for far less than the cost of a new head.

Your main concern here should be the wear on your intake valves, which I'm afraid has reached the point at which you will need to replace them. If you find that either of the two that need the most adjustment will not stay adjusted longer than one or two rides, they're done, and need to come out of the engine before they decide to leave on their own.

Your main concern here should be the wear on your intake valves, which I'm afraid has reached the point at which you will need to replace them. If you find that either of the two that need the most adjustment will not stay adjusted longer than one or two rides, they're done, and need to come out of the engine before they decide to leave on their own.

Could the one intake valve with zero clearance (on the oil filter side) have been pushing up on the cam all the time.. creating a lever which in turn pushed down on the journal on the clutch side.. creating this wear pattern on the journal bearing? anyhow are plasti gages the best way to make sure that the cam fit is within specs?

No, the pull of the cam chain off the outboard end of the ball bearing will add to the force pushing the cam upward.

Plastigage is the best way to measure the fit, but be sure to wipe the surface clean with a lint free rag before checking.

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I'm not sure.. but I think I need to get some new parts.

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Forgot last pic

Doesn't look too good, does it? Looks like a job for EDCo. Check the clearance anyway.

I'm curious:

> Have you ever had the cam caps off before? Has anyone else?

> What oil do you use? How often do you change?

> What oil filter?

Plan on opening up the right side and inspecting the oil pump.

Looks like the damage was from a lack of oil or someone over-torqued the cam caps.

I have only had this bike for about a month. The guy I bought it from said that his shop added coolant to the oil (when I got it the oil had a green tint). There was some brown chunky sludge looking stuff around the camshaft when I took it apart. The oil filter was also packed with chunky stuff when I changed the oil. I have never taken the cam caps out and I don't think the guy I bought it from had either.. the shims were all the same (1.88mm (.074 in). I'm thinking that the guy never changed the oil or something. Not sure what was in it before but so far I've changed it with yamalube 4 times and its still black just after driving it down the street and back.

... The guy I bought it from said that his shop added coolant to the oil (when I got it the oil had a green tint). There was some brown chunky sludge looking stuff around the camshaft when I took it apart. The oil filter was also packed with chunky stuff when I changed the oil....
Well, coolant in the oil would explain a lubrication failure, but if there is coolant in the oil, it will take on a milky brown semi-foam character, somewhat like a milk shake, and it won't lube anything. It's one of the worst mechanical disasters you can hope for.

I hope you got the bike cheap.

it was more of a dark grey-black with a slight green tint.. hope the bottom end is OK

Sounds like it may be time for a complete tear down and inspection. Great learning opportunity! Also may be the only way you are going to get everything cleaned back up and in good working order. I know it is a bummer to have to do all this work to a new to you bike, but you will be amazed at how much you can learn simply by taking it apart and putting it back together again. Good luck, let us know if we can help.

Josh

what kind of damage can I look forward to on the bottom end..? Or can I get away with freshening up the oil pump and top end..? have limited funds.. but I do have access to a new CNC milling machine.. do they have inserts or something for the cam journals.. how do they repair them?

Checked the clearance with the plastigage. .0015 on the filter side and .003 on the side that is worn the most.. any reccomendations. It still looks worn but should I run it for awhile and just keep an eye on it?

.003 is the wear limit. You're there. IMO, the head needs repair.

Well I finished getting everything back together FINALLY, started third kick even with some engine oil in the cylinder (11:30 last night so I didnt get a chance to ride). One last question though, I decided not to get the heads done, since both edco and another place here in florida said .003" is what they machine the cam journals to. Anyway after I took the head off I went ahead and double checked the journal clearance.. Now that I could get the torque wrench on there 100% and get things exact, the clearance was LOW! I had less than one thousandth clearance on the center journal bearing and the outside ones were basically the same. I decided to run it and after putting everything back together I noticed the intake cam didnt spin as good as the exhaust. So (me being a cheapskate) I went to the auto parts store and bought a brake cylinder hone.. I know I know its not exact but after a few seconds of honing on the journal I put the cam in and torqued it down.. spins good, not AS GOOD as the exhaust, but good. Now I think ive read on here that someone else had used a brake cylinder hone in the same way.. just wondering how it effects the reliability and are there long term effects that I need to watch out for. Thanks for everyones help and happy thumpin'

I was actually going to bring the head into work, make a jig and stick a boring bar into the mill... but thats too much work on company time, and would take a lot of persuasion.

To address the question of the lack of a hole in the center cam bearing saddle, the oil for the center and left bearings comes from the cap. It comes into the head behind the right end of the intake cam, and forks to the intake and exhaust cam right side saddles. There, it feed up into a passage in each cap that carries it to the left and center bearings.

Check your oil pressure at the cam feed fitting to be sure it's delivering oil correctly (see the manual). You may not have solved the underlying cause.

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