How to separate the GT380 crank.

[ukmxer]

Hello everyone. This is my first post here .
I am reliving my teens with the bike of my boyhood dreams.

3 days ago I bought a gt380 . The engine was seized solid. Bent the RH conrod which had ripped the wristpin from the piston.

I am looking at the crank and poised with mallet in hand but I thought I had better make sure before I start hitting it.

Could anyone please tell me how I separate the assebmly.

I dont know if I have to tap it or remove a lock pin .

Thank you

[yeadon_m]

welcome! er....don't do that. Unless you have a fully equipped workshop replete with multi-ton presses, you should not contemplate dismantling and reassembling a GT crank. I have heard of someone so equipped managing it successfully, but everyone else farms it out for new seals and, occasionally, main and big end bearings / rods.
Parts are all still available for the little GT triple. I have one, love it.
UK - I recommend SEP Kegworth. If you're not in UK, others will provide recommended shops who can do a nice job for you.
Cheers,
Mike

[jeff kushner]

I think that he's referring to removing the crank from the case, not disassembling the crank itself. No ukmx, there are no locking tabs holding the crank in place and if I picture your situation correctly, you are looking at the top crankcase with a cylinder attached, with the crank seating in the bearing lands? If the piston is still seized in the cylinder and you can't remove the crank because if it, you can carefully break the piston crown with a brick chisel, allowing the crank to GENTLY slide out of it's home. If the piston attached to the bent conrod is keeping you from removing the crank, you can also cut it in half allowing you to send the crank out for rebuild. I have a favorite crank builder but I'm sure that you's be better off finding someone on your side of the pond to avoid expensive shipping charges but ask around here first before sending it someone. On e member here is dealing with the incorrect rods being installed on his crank so you don't want to send it to the same place!!

Trust Mike, don't even attempt to pry the crank apart yourself or you will end up with a gouged, ruined mess!

GT380.....in red, it's one of the best looking bikes ever made IMHO

jeff

[ukmxer]

Thank you for responding.

Yes I have split the engine . And I wanted to press in a new rod myself. I have the equipment and experience for pressing 2t and 4t single cylinder motocross and enduro cranks but I have never done anything like this. That is what prompted me to stop what I was doing and ask Before I knackered it.

[yeadon_m]

There is a fellow on another forum http://www.kettleclinic.co.uk" onclick="window.open(this.href);return false; who pressed his own GT750 crank successfully - I can't recall who right now. If you post there someone will point him out.
Mike
Ps: yes, I've got wrong rods in a 550 rebuild! But, SEP did my 380 and that has always been impeccable - the post was on 380, or I'd have been silent on a shop

[Coyote]

I successfully did a crank on a single. An old 250 Ducati BUT, I had access to lathes, presses, indicators etc. Even with all the proper equipment at hand, it still was a bitch. I am a retired machinist with more than 30 years under my belt. I wouldn't attempt a triple crank on a dare. FARM IT OUT! --- no matter how much you THINK you know.