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gdbarr1976

cam srocket moved

12 posts in this topic

My guess is that this has happened to someone else. My intake cam seized and the sprocket moved on the shaft. Is it fixable?

And while I am asking, I am having a over heating problem. Two hours into a three hour hare scrambles I'm out of coolant. I have replaced the head gasket and torqued it per the manual. There is no apparent leaks. This bike is a 06 yz450.

thks

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You can fix the head, of course, and you could fix the cam. But that would require the sprocket to be pressed off, re-indexed, and pressed back on, then tack welded so it could not slip again. That's a time consuming process, all in all, and you still have a cam whose journals need refinishing. Better off with a new one, IMO.

As to the coolant loss, have your cap tested.

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There is a tool made for testing readiator caps. A bad cap is incapable of holding pressure. Pressure raisies the boiling point of the coolant.

Less pressure = lower boiling point=coolant boilover and loss.

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Unless you're a tool junkie, or you have a lot of different vehicles to work on all the time, take your cap to a shop and have them test it.

As William said, the cap is required to hold 16 psi on the cooling system because it raises the boiling point. Water goes from 212 to about 235, and a 50/50 water/antifreeze mix goes from 230 to 265. Preventing boilover helps prevent coolant loss.

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I had the cap tested at a radiator shop and it is good. The empeller is good.

I topped off the coolant then rode it in the dark on my driveway last nite. Even with air moving I was getting alot of glowing from the head pipe. I am beginnig to suspect a head gasket leak or even a cracked head. Any ideas?

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There is as much as 250-300 degrees difference in a glowing header that can be seen in the dark and one you can see in the daylight, even in the shade. And, a head gasket will not make a header glow.

If you can find a shop that can do a test for the presence of combustion gas in the cooling system, that will tell you reasonably conclusively. Otherwise, it's a little tough to tell in cases where there's not too big a leak.

Radiators coated with scale from hard water can cause trouble, too, since they don't transfer heat as well as they're supposed to.

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My guess is that this has happened to someone else. My intake cam seized and the sprocket moved on the shaft. Is it fixable?

And while I am asking, I am having a over heating problem. Two hours into a three hour hare scrambles I'm out of coolant. I have replaced the head gasket and torqued it per the manual. There is no apparent leaks. This bike is a 06 yz450.

thks

Ive noticed those 06`s seem to overheat way to quick... anyways, i have an 03 , and i installed an overflow tank from a WR, and it works wonders, install wasnt to bad, fairly easy, but it works wonders im tellin ya. consider installing on one your bike.

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I am beginning to beleive this motor is posessed. I have four 450's and one 250f in the garage. I have rebuilt all of them with no problem but this one is making me crazy. It was due for a rebuild so I put in a wiseco piston, and all new vavles. Used assembly lub and torqued the valve caps correctley and the cams seized and rotated the cam gear. I cannot tell you how many times I took it apart before figuring that the cam gear was the problem. Got all that fixed.

Now, I can't cure this over heating. Couple of questions. It seems to run a little lean after the rebuild. Could a lean mixture cause it to run hot ? As I reported before, the head pipe glows even when moving. I don't think it is the head gasket now since it gets hot within about 5min of riding. I don't tink it is a radiator problem. I have never run anything but 50/50 coolant water. Any more ideas?

Could the wiseco piston require a richer mixture?

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Yes a lean mixture will cause it to run hot, especially if you jetted it for summer hot weather and your riding in spring weather, you need to go richer usually when it's cooler out.

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try engine ice and getting your cap tested and search for the jetting procedures on tt. for the head send it to WMR in fl they will line hone your cam journals and will give you a quote on a cam if it's more than 50 to fix the cam get a hotcam for 120. good upgrade.

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