Topic: cam clearances

[hymodyne]

I've got a 650 cam in my 500/550 head. It moves freely, but there are a few places where the cam lobes come very close to the walls of the head. How much clearance do I need? Should I be concerned about expansion when the bike is hot that might cause the lobes to contact the sides of the head?

hym

[bwaller]

Hym,  it should only be "tight" at the top of the tunnel walls? Could you use a burr in a die grinder and bevel the top of that wall where the clearance is the least.

[754]

Dont eyeball it make sure it has clearance,,lack of clearancs may cause drag if there is a lot of oil there.

Wait and find out before assembling.

[Jay B]

Let us know how the 650 cam performs in your bike. I'vew been thinking of doing this for a while.

[squirley]

I am putting together my 550 head right now as I type this.  When I put in the 650 cam, there was no interference, but some of the lobes were very close the cylinder head  cast walls.  I just took a dremel and cleared them out to what the clearance was on a stadard 550 cam.  Right now, I think I cleared them out to have about .010 clearance between the lobe and the head.  I will double check and see what clearance number I wrote down for the 550 cam before I cleared the material.

[MRieck]

Dont eyeball it make sure it has clearance,,lack of clearancs may cause drag if there is a lot of oil there.

Wait and find out before assembling.

Yeah..... it will certainly cause drag if the lobe hits the cover or wall. If it's close to the wall relieve it with a Dremel.