t. dupree wrote on 12/31/69 at 16:00:04:http://www.picturefuse.com/picdetail.php?picid=42906The link above is a pic of the camshaft bearing on my 1987 650cc (looking through the valve adjuster access plate). As you can see, the bearing surface is gouged an metal is shaving off the journal. The book says that the head must be replaced if it is out of spec. I can assume that the crankshaft is worn also because the engine knocks like crazy. This bike was GIVEN to me, so I don’t have any $$ invested in it yet. Everything else on the bike seems fine except for broken turn signals.
My questions are; Can this head be rebuilt or is it scrap like the book says? If it can be fixed, will it be cheaper to get a new/used head verses trying to repair this one? Where can I get engine overhaul parts? Do they make oversized crank and camshafts?
Thanks, tom
Tom,
The camshaft runs in "plain bearings" in the head and headcover, and if there is damage to those, you'll have to replace both parts. I've never heard of oversize parts and cannot image how any regular machine shop could rebore the journals either. I do believe that you can have the cam reground if you decide to do that, though.
Now, I've studied this photo and compared it to ones that I've taken. (I'm about cross-eyed now, too). Is this looking through the intake valves? And what we see is the intake lobe on the camshaft? I see the scrapes on part of the bearing surface too, but that particular area is not under the headcover. The worst part about any scrapes is a loss of oil pressure....
I'd pull the headcover for a closer look before deciding....
Now, about the knocking sound in the bottom end. Can you tell where it comes from?