CB650 engine

[rudy]

Last weekend I picked up that CB650 SOHC 4 engine from Randy (harper750) for a buddy of mine. It's an 80 or 81 from what I understand. I think he plans to put it in a 4 wheeler or something. Anyways, a free engine doesn't come without a catch. So, in an effort to get this thing run-able for my buddy, I took the head off to see what I got. Well, I'll tell you what I've got. Two stripped head bolt threads (where it threads into the case) and one head bolt that wouldn't come out and rounded. I drilled the head of that bolt to get the head off, as I figured if I can't get that off, this thing's screwed anyway. The spark plug in cylinder 2 is broke off. Not just the porcelain, but between the hex and the threaded part. I honestly don't know how that happens, but I have the proof downstairs that it does!

So, upon more inspection, everything else seems in great shape. Cylinders are nice, pistons and rings are all pretty decent. Cam chain tensioners aren't worn much at all. Everything looks decent.

So, a list of things I'll be needing to get this hassie put back together and running:
-Top end gaskets - head gasket, cylinder base gasket (any other ones I should have???)
-Second in from the right, front head bolt. I can measure the part that was still in the case, as there are a few different length bolts.
-I have a HeliCoil set that I think might even be the right size for those stripped holes.
-Ratty old exhaust just for getting it running.

If anyone knows any other things specific for these Honda 4's to look for while I have the top end apart, please let me know. I'll be cleaning everything, maybe even lap the valves, who knows.


Lastly, what do you think something like this should be worth to him? Running of course, after I put my time and money into it. He wants to trade a 79 CR250 and an 80's Honda 175 dirtbike. The 250 apparently runs, and both bikes are ROUGH!! Like, spend at least $500 each to get them half decently reliable kind of ROUGH. My MX250 is in better shape. He also wants me to throw in a set of side fairings for his 84 CR250, so that means finding them, and buying them.


Any thoughts, please let me know.

 

[hamfast]

I haven't rebuild one of these before but i had a roomate who did, I can tell you the engine is pretty specific to itself when it came to cam sprockets and the like. The head bolts are avaible at Honda though not too expensive.

Go to www.mrcycles.com at get the Honda part3's then phone your local honda dealer for a price.

The bike sure was nice when it was finished.

Cam cover gaskets came in a couple of pieces i think

 

[rudy]

Ok, I'll try the local Honda shop next week. It's just down the road from work. The cam cover gaskets are a rubber ring gasket installed in a groove, they look in great shape. Just need the head gasket and cylinder base gasket.

 

[cbcafe]

If you order a top end gasket kit, make sure the rubber seals that cover the head bolts located in the center of the head come with the kit. Were the ones you removed damaged? If they are still in good shape, they might be reuseable. My honda top end kit ($200.00) did not come with these seals. I can't speak for aftermarket manufacturers. I managed to break a head bolt during top end teardown. Fortunately the stud of the bolt was protruding above the block surface. A little bit of heat and some vice grips took care of business. Which head bolts do you need? There are different lengths. I might have the bolts in my parts pile.

 

[Tim]

Western Hills Honda often has a good selection of stuff, including OEM gasket kits (its where I got mine from for my 500/550's). I have a few of those rubber seals kicking around too - new in the Honda parts bags. They don't tend to come with the newer gasket kits - came with older ones.