GT550 vs GT750 4LS front drum

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Kettletimes3
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Re: GT550 vs GT750 4LS front drum

Post by Kettletimes3 »

Can ask where you got that part number from.
Kettletimes3
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Re: GT550 vs GT750 4LS front drum

Post by Kettletimes3 »

I may be wrong but i think that parts list is from a later parts book,It lists J.K.and L models,
My book only lists J.and K models.Now i'm wondering if the very first 750J were fitted with a hub that was different to maybe a later
model J.And the same later hub fitted to the 550J.If there is a difference in the Dimensions between the two, it's the only reason why i think they would be different.
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Itspieman82
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Re: GT550 vs GT750 4LS front drum

Post by Itspieman82 »

Kettletimes3 wrote:I may be wrong but i think that parts list is from a later parts book,It lists J.K.and L models,
My book only lists J.and K models.Now i'm wondering if the very first 750J were fitted with a hub that was different to maybe a later
model J.And the same later hub fitted to the 550J.If there is a difference in the Dimensions between the two, it's the only reason why i think they would be different.
Mine is a late 750 j. The hub does not have the small spacers in either side of the brake plates. I do also have a j and k parts manual showing the said 6mm spacers. Upon me putting my wheel into the forks the spacers make the whole setup too wide so take out and hey Presto. It's very confusing as parts manual says yes. Physics says no. Lol. Like said before maybe the early kettles had a thinner hub to the later. Anyone shed any light?

Joe
1972 GT750J CANDY LAVENDER aka PINK haha
1973 T125 STINGER AZTEC GOLD
1975 GT380M GYPSY RED

What's next??? No-one knows hahahaha hopefully a gt550
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Alan H
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Re: GT550 vs GT750 4LS front drum

Post by Alan H »

I understood that some early kettles had slightly wider yokes. Perhaps they might need the spacers?
I haven't got an early kettle parts catalogue, but there's no spacers on the 550J.
Proof that four strokes are over complicated
teazer
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Re: GT550 vs GT750 4LS front drum

Post by teazer »

This conversation appears from time to time and we have not apparently come to the bottom of the story. I started a spreadsheet of relevant part numbers and that just added to teh confusion. So then I searched through a couple of different threads on here, and that muddied the water some more.

We have some part numbers and a few measurements, but what we don't appear to have is a complete understanding. The missing piece appears to be early versus late J model information. I have three different parts lists and none of them show the spacers that I have seen mentioned. Likewise the parts lists I have do not show the early barrels with bolt on manifolds. They just show K barrels for both J and K. Form a parts supply perspective that all makes sense but it's hard to work out what changed from early to late 750Js.

I have a suspicion that the first 750J had wider brakes in wider forks and that they changed to the 550 narrow drum plus spacers to make up the difference. That might explain why some of us have spacers and some have wider hubs and the parts lists don't reflect that.

So if anyone has a copy of parts list for early J parts I would appreciate a copy or at least of the barrels and brakes and forks pages. Then we can pass along the info to Ian Sandy to include in his GT750 guide.
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Alan H
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Re: GT550 vs GT750 4LS front drum

Post by Alan H »

I have an original 550J parts book at home that I bought back in 1972 when I bought my original 550. I also have a (scanned) service manual for all models up to 1973 giving technical specs for carbs, electrics, gearing and all settings if anyone wants a copy. Just pm me your email address and I'll send a copy when I get back home. I'll also do some measuring of the forks and front brake on my 550J resto bike in a couple of days.
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Kettletimes3
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Re: GT550 vs GT750 4LS front drum

Post by Kettletimes3 »

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I don't know why they duplicated.
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teazer
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Re: GT550 vs GT750 4LS front drum

Post by teazer »

Thanks. could you also post page 30-1 the first page of the front wheel part numbers 1 - 28 please.

That sheds some light on things for sure
Kettletimes3
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Re: GT550 vs GT750 4LS front drum

Post by Kettletimes3 »

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