Topic: Is this camshaft OK? The lobes are showing wear

[jaydog]

Hello! I am rebuilding the top end of my '78 550 because it was smoking like mad and the cylinder head gasket was leaking a bit on the left side. I have everything torn down and I am in process of cleaning and cleaning and cleaning, lol.

Anyway, I thought while it was apart I would put in a 650 cam.  I picked one up on eBay a little while back and tucked it away for now. I was inspecting it closely and some of the lobes are showing wear. There are some spots were the lobes have marks that are not shiny and clean like they should be, especially when I compare it to the 550 cam. There are a couple things that will catch a nail when you run it over the surface. The cam and rockers in my engine right now all look very good and I don't see any problems with those.

So I am thinking that I'll ditch the idea of the 650 cam and just reassemble with the orignal cam. But let me know what you think. I hope the photos show what I mean OK. Is the 650 unusable at this point? Are there any repair methods? I have read about hard welding but don't know much about it.

Thanks for the help! I haven't gotten this far with out all the help available here. I don't post much because I can usually find whatever I need with a search since you all know so much!

[goldarrow]

That shaft looks like need to be replaced.  But I would be more concern of what caused the wear.  I think your top end is at stake, specifically the oil jets on each side of the engine. 

[jaydog]

Thanks for the reply. That's what I thought about the cam too.

I'm ok because this is the 650 cam I bought and I can just go with my original. It's in great shape.

[goldarrow]

Sorry, I didn't read the whole post earlier.  But yeah, I wouldnt use the cam.  It can be repaired hard weld but I don't know anyone who does that though.  It may be cheaper if you source a new one

[andrewk]

I would get that completely cleaned up (degreased) and have a look again.  The pits on the bottom of the lobe aren't great, but I've seen a lot worse come out of a running engine.  The actual lobes look ok from those pics.

Do you have the rockers that came out of that engine?  Those could provide some clues as well.

[jaydog]

I only have the cam and the tach drive gear. I am leaning towards using my original. The 650 cam only cost me $30 on eBay so no biggie.

[dave500]

use the original cam and rockers,that cam looks dodgy and it will have to sort of re wear into your old rockers probably wearing them on the bad lobes,its best to use the rockers that were in the 650 with that cam,not many guys seem to do that though?

[jaydog]

Makes sense Dave. I bought the 650 cam at a time when there were a lot of threads about it so I figured... why not? Especially when I saw it for cheap on eBay. I am going to use the original parts since I really don't want to cause issues and the potential for trouble makes it not really worth it for me.

[dave500]

i'd prefer a new or re ground cam.

[HondaMan]

Maybe contact Megacycle and ask them about their hardweld rebuild? They can take your cam and remake it, even add different duration to it. Don't go for lots more lift, just add some duration (maybe 8-10 degrees more) and you'll find it really wakes up the engine. 

[jaydog]

Thanks Honda man. I'll check it out. Didn't know they could do that.