1981 GS650 E broken crankcase

[ncint2]

Hey guys I have a broken lower crankcase and was wondering what are my options for fixing it, I bought a lower crankcase to replace the broken one but after more research I found that they’re made as a set. Would I still be able to use the new lower part or could I possibly reweld the broken piece back together. Or should I just say forget it and buy a matching set somewhere. Any advice is greatly appreciated

[rphillips]

scrap that one and find a replacement, finding a complete ehg may be the best approach....Just wondering is that an eng. you've been running then it broke? or is it something you've got and don't know anything about it.

[ncint2]

If I find a crankcase set could I use all the internals I have already and just throw them in or is it actually better to find the complete engine. It was non running when I bought it for 100 dollars, it cranked and started for a couple seconds for a while but then just made a loud clank and it didn’t start anymore, I opened up the clutch cover and found part of the clutch basket was broken also, kinda bummed since I thought I had a mostly running motorcycle.

[Nessism]

You need a matched set of cases. I suspect a good many of your internal parts are usable, but not all. You should focus on making sure you have the proper crankshaft bearing shells. I've never built a 650 so I'm not familiar, but no doubt, the factory service manual details out how to match bearings to crank.

[ncint2]

As far as I know mine does not have crankshaft bearing shells, it has ball bearings and holes for the pins to lock in onto the crankcase. As for buying a new crankcase set, should I buy only gs650e or do gs550 or gs650 models also work, I know that the gs650 e is just the gs550 lower with gs650 upper half

[rphillips]

From what you say, You got real big problems. to answer your question, yes all the inner parts should fit fine. Beware there are differences in the 650E and 650G engines. The loud "clank" and the broken clutch would point me to finding a complete eng., which is also a gamble.

[Nessism]

As far as I know mine does not have crankshaft bearing shells, it has ball bearings and holes for the pins to lock in onto the crankcase. As for buying a new crankcase set, should I buy only gs650e or do gs550 or gs650 models also work, I know that the gs650 e is just the gs550 lower with gs650 upper half

Ah, E model. I missed that. So roller crank. Again, you need a matching set. No mix and match.

[ncint2]

I'll try finding a complete engine then, do you guys know what I can do with internals then, I have everything labeled and sorted so could I try selling it or giving it to someone. Again thanks for the advice

[Nessism]

There is a 650E engine on eBay, in Ohio. Not horribly far away from IL. You can likely part out the spare parts and break even...

Or, there are a set of cases...in the UK. Price is cheap enough, and only $100 shipping. Worth a shot.

https://www.ebay.com/itm/402121422425

[650Skull]

These bikes are getting hard to find. If finances allow I would b keeping all parts not needed for for another engine for spares.

[ncint2]

These bikes are getting hard to find. If finances allow I would b keeping all parts not needed for for another engine for spares.

Yeah but unfortunately the previous owner tried to chop it up into a cafe racer, a bunch of bolts are stripped and the airbox was cut into pieces but for now I'm just trying to get a running engine and then deciding on what to do with it cosmetically,

[KiwiAlfa156]

I've used a set of unmatched cases before to build a GS engine, not considered ideal, due to the critical alignment of the cross-joint line boring of bearing journals. I had two sets of crash damaged 1100 cases with a good top and a good bottom case between them and thought 'what have I got to lose'? I'd heard that a local racer had replaced only the broken lower case on their GSX1100 race motor with success so I gave it a go. In my case (pun intended) the cases matched together perfectly with no alignment issues for either the crank or gear shafts, etc. In fact the engine ran well for many years until I sold the bike. Whether I was just lucky, or whether the automated line boring and machining processes accurately repeats during manufacturing to provide workable tolerances between unmatched cases, I do not know. But there is nothing wrong with testing the excepted truth, which sometimes is accepted because it is oft repeated.