Topic: CB550 Cracked Upper Crankcase

[josuepdx]

Hey everyone!

One of my neighbors is selling their 1978 CB550 for $400 and I was wondering if it was going to be worth it or what fixing it would exactly entail of. The upper crank case is cracked where the front engine mounts are. Seems like an interesting thing to crack, right?Any ideas how this could happen? Couldn't find anything about it online or on the forum so I was wondering what you guys thought? $200 sounds like a better price to me considering the condition. The bike was a "daily rider" till this happened, but they really don't know what happened. They guys mom is selling the bike for him (moved to NY) and doesn't know what the story is.

Anyways, upper crankcases aren't that expensive and rebuilding the engine seems like "fun". Everything else is there on the bike minus battery, seat, AND A WORKING ENGINE OF COURSE. Anyways, seems like it could be a good winter project.
I looked closely at it and there doesn't appear to be any other damage on the frame caused by the engine failure. Would I be able to get away with just the top crank case? I know some people have mentioned matting issues... If that is so, would my option just be a whole new bottom end then? Does that seem worth it?

Thanks!
-Josue

[dave500]

the cases are machined as a pair and must be kept together,post a pic of the damage,it might be weldable?these engines are well bolted in,show us a pic and it might even be able to be run as is?these engines arent a stressed member of the frame.

[tomkimberly]

If it's nice, I'd buy it as a replacement engine can be had for less than $ 300.00

Tom

[josuepdx]

I'll go grab a picture tomorrow if I can. The crack is fairly substantial though and really doesn't look fixable. Maybe a few inches long and big enough to maybe put a pen in there. MAYBE. I just don't get it though. There's no damage to the engine anywhere else. No fin damage, exhaust damage, or engine side cover damage for that matter. Makes no sense to me.

[dave500]

yeah it may be ok to use?just unsightly?

[josuepdx]

The crack almost looks like a god damn hole. I'm certain oil will just spew out of the frickin' thing if I started it.

[dave500]

get those clear pics up!

[bwaller]

Maybe it's something on the inside trying to get out!

[mickwinf]

It has been known for the engine mounting bolt and nut to seize into the crankcase and when attempting to remove it cracks the alloy, nasty!

[josuepdx]

Alright, here are the picture of the bike and the damage. Talked to the owner on the phone, he said the thing crapped out on him on the freeway going balls out from Portland to Seattle, 2 up. I guess the thing just stopped pushing, pulled the clutch, and  pulled over. Been sitting ever since sometime in 2010-11 or so. Bike doesn't kick over any more, could be seized.
Kind of interesting, the bike is in KM and not miles. Has 40,000 KM on it, so... about 25,000 miles. Not bad.

I've been looking on ebay, engines are around $450 for the cost +shipping. Seems kind of steep, but I guess shipping an engine is costly. I've been looking around portland, and can't readily find an engine for sale. I guess I could just wait till a good deal pops up.

Talked to the guy and offered him $200, he doesn't seem to happy about it. He might take it but he then moved to $300. Supposedly someone offered him $400 just to part it out. If I did get a new engine, I could part out the old one and probably make at least $150 in parts I would imagine. Do you guys think it's worth it?

[Bankerdanny]

Well, it's intact and complete. I would bet a good welder could weld that piece back in.

But honestly, a 550 engine should cost $100 or less and to get that welded you would probably have to split the cases anyway. Once you are at that point you might as well just replace them.

$300 for a complete and titled bike seems worth it to me.

[lucky]

Well, it's intact and complete. I would bet a good welder could weld that piece back in.

But honestly, a 550 engine should cost $100 or less and to get that welded you would probably have to split the cases anyway. Once you are at that point you might as well just replace them.

$300 for a complete and titled bike seems worth it to me.

That is going to have to come apart to be welded.
It needs TIG welding with 4043 filler wire.
It has to be very very clan -no oil at all.

[josuepdx]

Friend of mine has a K1 1972 CB500 engine that he's willing to sell me for $150. He hasn't heard it run, but it doesn't have a massive hole in the crank case! Should that thing just drop right in and mate up with the engine mounts/ exhaust from the 550?

Any reason I should stay away from a 500 engine? I'm not terribly concerned about the loss of 2hp.   

[dave500]

itll drop straight in,youll need the 500 clutch cable.

[bryanj]

To break there i will lay odds that it has been wildly mistreated, has little(if any) oil in it and has thrown a rod. If i am right it would also be the first 500/550 I have ever seen with a rod gone----I only ever seen one worn out crank and the oil in that was like grinding paste