Author Topic: 550-650 cam mod question  (Read 525 times)

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Offline 88BuckMeister

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550-650 cam mod question
« on: January 18, 2024, 05:41:08 PM »
As some of you may have seen (or not) that in my 74 CB550, I've installed the 591cc big bore kit, and just got my CB650 cam in. It is in fact the real deal, American made (not the German export) with low miles on it. But as I suspected may happen, I'll have to take some material off the head for the lobes to clear.

My question to you all is IS IT SAFE if I'm careful and tape everything off to take some material off the webbing while the valves and springs are still installed? Also, how much clearance is desired? Only one lobe contacts, but some of the other lobes have very little clearance. There's one pic in here that shows good/sufficient clearance. Those are all on the intake sides. Pretty much that entire side looks like that. Thanks all!

Buck
« Last Edit: January 18, 2024, 06:08:07 PM by 88BuckMeister »

Offline Mark1976

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Re: 550-650 cam mod question
« Reply #1 on: January 18, 2024, 06:35:02 PM »
   Is that a freshly rebuilt head...
Start with the end in mind...

Offline 88BuckMeister

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Re: 550-650 cam mod question
« Reply #2 on: January 18, 2024, 06:46:41 PM »
   Is that a freshly rebuilt head...

...yyyyeeesssss....

Offline Mark1976

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Re: 550-650 cam mod question
« Reply #3 on: January 18, 2024, 07:37:20 PM »
   Well, you can but jeez. Its not the end of the world, you'll need to really tape off the entire top of the head except the area being clearenced, and I mean tape it off, use a good quality duct tape, not the cheap junk. Make sure its clean and dry. Buy a small fine file (round and flat), I filed because i didn't need all that aluminium floating around from a grinder.
   I've done it, in the bike, so it can be done. Use a sharpie and mark off the area in question so you know exactly where and how much your removing. Do one side at a time (I did the right), all mine were on the front (exhaust) side of the head, looked just like yours. Finish one, vacuum it out and check it.  Put the cam in and and check the clearance, I think I made .015 possibly .020 between the lobe and the wall. If you need to, pull it out and file it some more. The only area not taped is the trough the oil gathers in under the cam, that's where your filings can collect to then vacuum out. The after pic is hard to see but its done. Keep it taped and clean, one side at a time.
Start with the end in mind...