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Cam ID

6 posts in this topic

I'm curious as to what cams are in my 426. Where are they marked? I need to pull them anyway to adjust, haven't yet but here's what I could see:

 

I0Q9pHOh.jpg

 

b7SBeZnh.jpg

 

Ku421Q9h.jpg

 

They are auto decompress. I don't yet know if they're 450 cams or what exactly. Also need to figure out what clearances I should run. Exhaust is awfully loose, loose .009-tight .010. 

 

Thanks for any advice. 

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Clearance is .004-.006" intake, .008-.010" exhaust.   (.10-.15mm and .20-.25mm)

 

The intake cam is not the OEM cam.  If it's aftermarket, it will usually have some markings on it someplace.  The exhaust cam looks like 450 OEM , but it's impossible to tell for sure from this.

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For some reason I thought my manual said 4-6/6-8, but looking at it now you're right that exhaust is 8-10. If they're something other than stock, should I run the same clearances?

 

How can you tell that intake isn't stock? The pattern of the slots in the sprocket? 

 

Do these ever have problems with sprockets slipping? Would be easy enough to TIG the cam to the sprocket when I take them off if I should. I'll measure lobe sizes with a caliper when I have them out too, not sure I have a mic the right size. 

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The OEM cams on a 426 both used the same sprocket, so the sprocket had three timing marks, one labeled "I", and another labeled "E".  Since the intake sprocket has no labeling and only two marks, the sprocket itself was made later on, so the intake isn't original.

 

Yes, run factory clearances.

 

The sprockets do rarely slip, usually only where there has been a full or partial seizure of the cam in its bore.

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Thanks. 

 

As it sits, I don't have a manual decomp. If find the stock parts, would it work? It might be nice to clear it if I drop it and it floods or something.

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Yes it would work.  The entire setup is actually available as a kit for the '03-'05 YZ450F models that still had the machine work in the head to accept it. 

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