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'74 GT550 Q's re infamous blown starter clutch...

Posted: Wed Jun 20, 2012 12:52 pm
by barncat
i'm a long way into a '74 GT550 cafe project and quickly discovered the starter clutch problem upon reinstalling the modified wiring harness- was just testing the e-start system, not trying to fire it up fortunately. figures, i was not aware of this notorious issue with this motor... the P.O. had been sporadically running the bike by pop starting it, as the kick shaft is snapped off at the splines. the large diameter starter clutch gear hub is destroyed and the starter clutch moving parts are shot but incredibly no other damage.

(i came back and edited this after some study)- apparently, as with some other motors and makes it is possible to just delete the whole starter clutch assembly and go kick-only? it looks like the needle bearing/bushing and thrust washer are adequate support for the clutch basket...

also, assuming adequate TIG weld penetration, will there be any embrittlement issues with welding the kick shaft end back on? it's either that or split the cases on a motor with great compression that isn't leaking a drop of oil. not fun.

Re: '74 GT550 Q's re infamous blown starter clutch...

Posted: Wed Jun 20, 2012 3:14 pm
by jabcb
See Service Bulletin GT-26 for the fix.
http://www.ozebook.com/compendium/techb ... 022-26.pdf

The upgraded clutch / start clutch assemblies are available on eBay from time to time.

Re: '74 GT550 Q's re infamous blown starter clutch...

Posted: Thu Jun 21, 2012 6:15 am
by barncat
thanks for the link to the repair but i've already read that, and there is nothing on eb*y at present, and i need to finish this bike. and kick-only is more dependable and "old school".

so i'm looking for input from anyone who has just eliminated the starter clutch setup entirely- as in race bikes etc... i'm going to put in some more time on it today.

my main concern is that the 22mm x 42mm x 2mm thrust washer is not adequate to back up the whole clutch basket assembly against the shoulder on the tranny shaft. looks like turning a bushing on the lathe that supports the thrust washer against the case bearing is the way to go?

Re: '74 GT550 Q's re infamous blown starter clutch...

Posted: Tue Jun 26, 2012 6:21 pm
by barncat
here's how you delete a broken starter clutch:

machine a custom bushing that's radially grooved internally and axially drilled (for oil) to back up the hardened thrust washer to keep clutch basket safely located.

also TIG welded fresh splines back on the snapped kickstart shaft to avoid splitting the cases. deeply chamfered both sides to get adequate build up.