Cam question.

[750jim]

I lost a cylinder on my bike the other day, I have a low mile honda-matic top end to swap on to it and I know the cam is a much less agressive grind than the 5 speed cams. For cams I could put back my 1975 cam or I have a F2 motor thats frozen but the cam is nice (another low mile motor), I have heard the F2 was supposed to be a "hotter" engine. Anybody have any thoughts?

 

[dirtdigger]

The f2 cam can be used but you really need to degree it with a degree wheel because it has more lift and duration but the actual timing is retarded(late) compaired to the k motors and it is easier to have the pistons kit the valves if not checked properly. I would just drop in the K cam or get an aftermarket cam if you are looking for a hotter cam. What do you mean by lost a cylinder? Do you know the cause so it doesn't happen again?

 

[750jim]

I wish I had the funds to just buy a new cam for it, but its not in the cards anytime soon. I havent torn it down yet but it has no compression on one cylinder and sounds like its all blowing out the exhaust, no smoke though. The spark plug in that cylinder always had more carbon buildup on it than the rest of them.

 

[K2750tracy]

Sounds like you have a stuck or bad valve I would pull the head and check the exhaust valve on that cylinder.

 

[dirtdigger]

Have you checked to see if the valve is being held open by having no valve clearance? It more than likely will still need to be replaced along with the seat in the head or just use a different head. Could be excessive carbon holding the valve open too but then you have to determine the cause of the carbon...guides or rings.

 

[750jim]

I checked the clearance in hope of a quick fix but the clearance is where it is supposed to be, I am ordering a gasket kit and will be tearing it down soon. I was hoping the F2 cam would just be a "drop in" type of deal, I had read that the cam timing was retarded but the lift and duration were a little bit better than my cam so I wasn't sure if it would even provide any more performance than my 1975 cam.

 

[dirtdigger]

It would be less of a hassle to just use the 1975 cam than the f2 cam. Let us know what you find when you get it apart.

 

[750jim]

Ok update time, I finally got the engine out and the head off and my exhaust valve is missing a piece! It was most likely burnt since I put it back on the road as I could never get it to idle perfectly no matter what I did to it.View attachment 1657View attachment 1658View attachment 1659View attachment 1660

 

[dirtdigger]

Pictures dont work, maybe Travis will be able to fix it so they come up.

 

[750jim]

Darn hopefully he can, if not maybe I can get them posted some other way.

 

[750jim]

2nd try with the pics.