1973 GT750 Rebuild – Rethink

More problems – so making a few changes to the project plan.

Once I had the Calgary donor bike stripped down, I was able to put its frame along side the Kincardine frame and then noticed a few differences. Earlier GT750 frames in 1972 had a 2 bolt hole side stand and in late 1972 for the 1973 model year, this was changed to a 3 bolt side stand mount. For some reason, the Kincardine frame was the earlier 2 bolt hole style, and the side stand itself was not original and would need to be replaced. As well, on closer inspection I found that the Kincardine frame had a broken engine mount. The engine and frame for the Calgary bake were original and so the serial numbers very nearly matched (Suzuki frame and engine serial numbers seldom match exactly, and can actually differ by a wide margin). As they were original and close, it seemed a shame to give that up. The frame was cracked in the rear fender stay – not really a key structural member and so could easily be welded. The centre and side stands were both in very good shape. The engine was another story entirely. The Kincardine frame of course had no engine, and so would have been a ‘bitsa’ bike anyway – given a choice then of building a ‘bitsa’ or doing a restoration, I decided to restore the Calgary frame and engine. Of course nothing is ever easy …..

Whenever the Calgary bike had been parked – sometime back in the 1980’s – the oil was allowed to drain out and then it had sat outside in the snow and rain for the next 25 years or so. The barrels came off easily using the puller, but the sight that met my eyes once I cracked open the side cover wasn’t pretty.


There was a lot of rust – my guess is that the engine probably had been in good condition when parked, but over the years had gradually become seized solid with corrosion. Basically other than the cases, barrels, cylinder head and side covers there wasn’t much else I could really use – luckily I have several sets of transmission clusters, and crankshaft assembles so I can replace all the internals with parts from other engines. This does cause a bit of a potential problem though, as the number of teeth on some of the drive and intermediate gears changed over the model years, and I’m not sure which model year cluster sets I have on hand. As well, I will have to mix and ,match the gear sets a bit to minimise the lash in the drive train. Normally there are paint codes on the inside of the engine case, and sometimes on the gear clusters also to assist with lash adjustment, but for some reason this engine had no paint codes inside at all. The water pump, not surprisingly, is shot but I can either rebuild it or replace it. More work than I had expected, but all very doable.

Today I took in a GT750 crankshaft to Greg’s Cycle here in Calgary to have new seals installed. Assuming that nothing much else is wrong with it, I expect It should be ready in about 2 to 3 weeks.  I still need to check the barrels to see whether I need to use over-sized pistons, or just re-use standard size ones, but that can wait till after the crankshaft is finished, and I have the gear clusters, crankshaft and all the other bits and pieces back in the cases.

The next few weeks then will be busy getting the above items sorted, plus I have another item I need to prepare for also. Our club is having a ‘powder-coat’ day here in Calgary in early September which I’d really like to take advantage of. This is made possible by a local supplier and basically you show up with your items prepped and ready to go, and take them home freshly powder coated for very reasonable rates. With a bit of luck I hope to have both a GT750 and GT500 frame ready to go, together with all the bits and pieces (battery box, side and centre stands, swing arm etc.).

Of course that means I’ll need to strip down the 1977 GT500, which I haven’t really even looked at yet.

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1 Response to 1973 GT750 Rebuild – Rethink

  1. Pingback: 1973 GT750 – Sods and Odds | Notes From the Corner

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