Gs550 crankcase splitting

[StevieB]

Hi, got an American import Gs550e with electric start and was planning to fit a Kickstarter from a donor bottom end that I also have.

Is it possible to just split the crankcase to fit the kickstart gear mechanism but leave the top end intact? Was hoping to split it upside down leaving the crank and all top end on bench and lift bottom half of crankcase off.

Is this possible? Cheers.

[Swiss Toni]

You may find there are subtle differences in both sets of crankcases. If this isn't so, strip the clutch out and remove the blanking/lock plates bridging the case halves. Make sure you've got all the bolts out. You can then strip the bottom case away from the top. I'm not so sure a kickstart will fit a 'non kickstart' crankcase! Wouldn't it be easier to fit your top end to the kickstarted bottom end?

[StevieB]

Thanks for the advice. Will take off the clutch cover and take a look. Could rebuild with kickstart bottom end but unknown mileage or history, and really wanted to keep original engine serial number.

[wraith]

Clutch covers are different I believe, so some internal parts maybe (gearbox and clutch) I'd have a good look at a manual before you start striping bits.

You could always put a gs650 top end on the spare bottom end 

[Poldark]

3 hours ago, wraith said:

Clutch covers are different I believe, so some internal parts maybe (gearbox and clutch) I'd have a good look at a manual before you start striping bits.

You could always put a gs650 top end on the spare bottom end 

Covers are different; one has a hole for the kicker shaft.  I think this has been discussed in detail on thegsresources.com 

I'll try to help you where I can; I have 550 engines in both kick and non-kick version.  Unfortunately, I don't have clutch covers removed from my non-kickers right now.  650 top end on a 550 lower is a good combo; this is something I have planned for the future.  There are aftermarket pistons to increase the 650 to a 700 or 740cc.  

[StevieB]

Thanks for the advice.

Just rebuilding the rear brake system, the engine is the next job. Originally only got the bottom end for the sump as my thread had stripped from previous owner. The engine has a kickstart so thought nice easy job take off clutch cover and it would just slide in - how wrong could I be. I will take the clutch cover off and see if there's a blank between the two crankcase halves. Or wether they did change the crankcase machining for the shaft not to be fitted. If I can't then I shall just rebuild a spare engine. Handy to know a 650 top end will fit - cheers.

Will update when I've had a look

[Poldark]

On the kickstart engine, the cases will have to be split so material can be removed to make room for the larger 650 bore liners.  I think it should drop straight in on the non-kick engine cases.  If the 650 donor is a chain drive model, the whole top end can be used.  If using a shaft drive 650 donor, the 650 cam sprockets are the wrong tooth count.

[StevieB]

Had the clutch cover off my 1980 electric start bike. There is a machined "hole" and 3 inserts for a kickstart mechanism in the bottom end. Just need to decide if I'm gonna take apart a perfectly serviceable engine to fit a kickstart or wait till camchain change in the near future when reaches 40,000. Only other factor which will make me do it now is if I can't get the sump off as sump plug thread stripped and I've got another sump.

Will take a search on here for sump advice, and here's pics of the kickstart machining in electric start bottom end.

Edited April 5, 2020 by StevieB
Add pics