GT550 Starter Clutches (and other harder to find bits...)

[2StrokeDreamer]

Greetings, all!

First a bit of an introduction - I'm a Kiwi that moved to the UK a couple of years ago, and at the point where I'm pretty sure I'm staying, so I'm in the process of putting down some roots and building my bike collection back up. I've always had a huge love of 2 Strokes, though have only previously owned an RG150 and RGV250 (VJ22, which I fully rebuilt the motor and de-restricted it - which was all great until one day I put it back together after cleaning out the carbs and forgot to put the 2 stroke oil back in - being a poor student at the time I couldn't afford to get the bores re-plated so it got sold, but I wish I'd hung on to it). The RG150 was my first crack at rebuilding engines after the piston blew apart at a race meet - had a lot of fun riding and rebuilding that bike, tbh it spent more time in bits than it did on the road/track.

Anyway, before I start rambling too much, I've already re-acquired my other favourite bike - an original Ducati Monster - and now am considering a 2-stroke project bike as the garage in the new house will be a suitable place to work on such a thing.

I am dead keen on the GT550 as I've always dreamed of owning a Triple, and the Kawasaki's are now sacred museum pieces (with the price tag to match). There's a couple of reasons for the GT550 rather than the GT750 - the 'barn finds' are a bit cheaper, I love that Ram Air cover look, and since being wooed to the air-cooled Monster after many years of race-replicas, I have a real soft spot for air-cooled engines.

However - before buying myself a donor, I want to be reasonably certain that I'm not getting something that I'm not going to be able to get critical parts for (I am only concerned about the engine as the project will not be a restoration as such) - either for the immediate rebuild or to hold in stock for future replacement (I do intend to ride it, after all).

The Starter Clutch is one particular piece that I'm worried about. It seems to be complex enough that it would have to be an original part (whether NOS if they still exist, or from another engine) - while given enough £££'s one could get custom crank/rods/pistons machine/fabricated, I'm not sure if there is a viable alternative to something as small, yet critical as the Starter Clutch assembly. I know rebuild kits for the original type are still available, but it also sounds like they just fall apart? Or is that a reference to the rollers/springs/etc that are in the rebuild kit? If I end up with a motor that has the Borg Warner type in it, are they fairly reliable or do they also suffer over time?

Has anyone ever looked into having reproduction parts produced, of either type, or an alternative design, or shoehorning bits from other models?

And beyond the Starter Clutch assembly, are there any other particular pain points when it comes to finding parts for these engines?

Sorry for the long-winded post, cheers for reading

[Alan H]

Early starter clutches are ok if looked after, but the later ones are better. Parts are available for the late ones, but other tgan springs, collets and rollers, not for the early ones - but there are rumours that some 'may' be planned. Other than that, kickstarting is easy and parts for clutches do appear on eay from time to time. Do searches on here for GT550 resto information, there's lots - I'm currently on with an A rebuild and a J resto - having gad 'several' since 1972 when tbey first appeared in the UK.
Which bit of the UK are you in?

[2StrokeDreamer]

Cheers Alan, you've just reminded me of a question I forgot to ask:
Is the Starter Clutch only used by the starter motor, and kickstart is not affected? If so then that is much less of a concern... I actually quite like kickstarting (I'd really like it if the Monster had one - though I'm sane enough to want electric as well in that case ). I had assumed it was for both starting mechanisms, leaving bump-starting the only alternative if the Stater Clutch is a gonner.

I am definitely working my way through some posts, this one is possibly a bit premature as it'll be a couple of months before I'm seriously looking to buy a donor (waiting for leftover funds from the house purchase - I should probably be allocating them to bathroom renovation and general redecorating, but those jobs are going nowhere whereas the GT550 just gets rarer... ).

I'm based in Glasgow.

[barney01]

Hi and welcome to the forum
The early starter clutches are prone to breaking up which is why they changed to the Borg Warner a much better design. As stated the early model rollers and springs are freely available as are second hand clutches. The later Borg Warner parts are hard to find anywhere. They are 2 different designs and parts are not interchangeable. See below for detail (GT-26)
http://www.oldjapanesebikes.com/mraxl_G ... ins/page-2
Again welcome and nice intro!

[Alan H]

Cheers Alan, you've just reminded me of a question I forgot to ask:
Is the Starter Clutch only used by the starter motor, and kickstart is not affected?

Yes, but as Barney says, the inner race that the rollers run on tends to crack and break up and if it does, can ruin the clutch and also lock the engine.

[2StrokeDreamer]

Well I guess if I end up with a model with the early design I may just remove the electric start entirely - one less thing to go wrong!

[barney01]

First picture is the two starter clutch gears
Second is what can occur to early gears.
It is possible to detect the early gear break up as they start to crack first.

[barney01]

If you are considering buying a GT550 there is also something else you must consider; US models were fitted with iron liner barrels that are designed to wear and can be rebored several times. The models destined for the EU after 1973 (L to B) were fitted with barrels plated with SCEM (Nicasil)where the piston rings were designed to wear instead.
Its quite expensive to repair the plated barrels and cheaper to rebore the iron liners.
Its your choice just giving you the heads up

[2StrokeDreamer]

Aye, I'd read on OJB that there is a conversion for the EU models around about when the M came out. Most of the ones I'm looking at are US 'barn find' imports so they'll all be iron sleeved. I'm not bothered if it ends up being nikasil though - I'm pretty sure that they can be re-sleeved with iron liners? I think I read that here in another post. Otherwise I'll just have to be prepared to shell out the £££s for re-plating when the time comes. It's going to be a forever bike so if I have to spend the money then that's what I'll do.

[Alan H]

Aye, I'd read on OJB that there is a conversion for the EU models around about when the M came out. Most of the ones I'm looking at are US 'barn find' imports so they'll all be iron sleeved. I'm not bothered if it ends up being nikasil though - I'm pretty sure that they can be re-sleeved with iron liners? I think I read that here in another post. Otherwise I'll just have to be prepared to shell out the £££s for re-plating when the time comes. It's going to be a forever bike so if I have to spend the money then that's what I'll do.

Yes, I fitted a set to Mike Yeadon's 550 earlier this year (Mike ably assisting of course!)
Spares are available though - I have 'several' in the stash.....