SUZUKI GT750 PROJECT.............................
Canadian Ian R Sandy converted several wrecked Suzuki two-strokes into one working Kettle. His aim was to build a fully functional motorcycle which looked like it’d never been taken apart in the first place. Did he succeed?
Canadian Ian R Sandy converted several wrecked Suzuki two-strokes into one working Kettle. His aim was to build a fully functional motorcycle which looked like it’d never been taken apart in the first place. Did he succeed?
Replacement exhausts for this model are not available, other than spannies of course. New exhaust systems for later models are available from Delkovic. I’ve bought a couple of sets of these and while they do look nice, I am disappointed with how they sound. They are quite different from the earlier style of exhaust to look at and would not be easy to fit.
For the 1974 model year the GT750’s frame was changed to accommodate a new exhaust system, and the rear hanger mount differs quite a bit from the earlier models. The exhaust hanger bolt location was moved back an inch from the rider’s left side footrest. Digging through my stores exposed a set of usable pipes of the correct style, needing only some minor welding to repair the inner pipe hangers where fracturing at the mounting bolt hole is a common issue. I also had a used set of the black cones that fit the rear of the pipes and give the 1972 and 1973 models their very distinctive look. New cones are available from Badge Replica in Australia, and the same ones are resold by Diablo in Canada. Funnily enough, depending on the exchange rates, it is often cheaper for me to buy directly from Australia…
The chrome on the pipes isn’t in great shape; hopefully they will buff up. Some people have their exhausts re-chromed, and I did a set of T500 pipes once. It is difficult to do with pipes fitted to the early triples for two main reasons: getting them clean enough to be chromed is not easy due to the sound absorption material in the front of the pipes. Secondly the internal baffle plates after all these years are often fragile and will frequently fail soon after any sort of aggressive chemical cleaning. Baking the pipes at a high temperature can be an effective cleaning option. Top Gun Coatings in Calgary offer that as a service, and it is a process also used to remove powdercoat and paint from steel prior to refinishing in a number of industries.
Often if the removable baffle has jammed, you find that the internal baffle plate has been damaged as it is only spot-welded on the inboard side of the pipe. The outboard side of each baffle just sits against the outer shell of the pipe and is unsecured, so when pulling out a jammed baffle the internal baffle plate gets bent. I’ve included a couple of photos supplied by my friend Richard which show the internal design. The only way to repair a damaged internal baffle plate is to cut the pipes open lengthwise. While it is open, you can sand blast the internals, check the internal baffles and repair as required, repair any of the external dings and road rash on the pipe shell, and then re-weld the pipe before having them chromed. Note: If doing sand blasting on the early GT750 pipes (J/K style), take special care as the fibre material secured under the metal mesh may be asbestos.
Rather than change to tapered bearings for the steering head, I installed new ball bearings in the original bearing cups of the fork yokes. As is usually the case with North American bikes – especially in Canada – the riding season is so short that the bearing cups are seldom worn. Ball bearings work fine for the most part and are cheap to buy. Just remember that the yokes and top bracket on the ‘J’ are 1cm wider than those used on the disc-braked versions. As the aluminium top brackets are often cracked at the pinch bolts, you will need to take special care when trying to locate a replacement should you need one.
The swinging arm bushings on the early ‘J’ models all originally appear to have been steel, replaced by fibre ones during the ‘K’ production. They also all seem to be solidly corroded in place as the only time they were ever greased was likely at the factory! Aftermarket bronze swinging arm bushes are available, and there are people who insist that the difference in handling is noticeable, but I used the fibre ones for this build as I think they are good enough for the usage this bike will see.
From my spares stock and after canvassing a few friends, I had a full set of usable original paint purple tin (called Candy Lavender by Suzuki, but fondly referred to as ‘Man-genta around here) to complete the job. I re-united the engine with the frame and moved onto the next part.
I have a collection of used wiring harnesses and they are all shot. Grabbing one out of the pile, I peeled back the sheathing to get a good look and found that a short had taken out one wire for pretty much the whole length of the harness. You often find that the connector block joining the front and rear main harness shows signs of overheating, so I almost always replace that block. The other common failure point is the in-line fuse which I scrap as a matter of course and replace with a modern blade style.
I rebuilt the main and sub-harnesses with new wire (heavier gauge in some cases than original) along with several new original style connectors which I buy from Vintage Connections in the USA. As well, I replaced the black plastic sheathing on the harnesses, handlebar switch leads and elsewhere along with rebuilding all of the switchgear, the indicators and the correct rear two-bulb tail light. I did not renew/refresh the outside of the switchgear, just leaving it looking weathered and worn.
Normally I re-key the ignition, steering lock and seat lock (on those models that have one) so everything is keyed alike (see oldjapanesebikes.com for more info on this). The 1972 and 1973 models used a singlesided key and I didn’t have a suitable ignition switch with the correct key style at the time of the build, so for the moment at least I’m using a later style. I will circle back and correct this at a future date.
I installed an Accent electronic ignition from Germany. These are an excellent design having no silly black box you have to hide somewhere, have been very reliable, and cost about the same as a set of all new points and condensers. I also installed a new style electronic voltage regulator and rectifier which I buy from Oregon Motorcycle Parts. They work well, and the regulator can be easily adjusted so you can precisely set the charging voltage, which I think is a useful feature.
The clocks/gauges were also a mess. The 1972 model gauges have a plastic shell which is almost always cracked. Suzuki changed to a metal shell for the 1973 production. I had the plastic 1972 ‘J’ clock shells reproduced and put together a short online ‘how to’ guide for people who want to take a chance on their own repairs. The gauges are easy to ruin, so if more than just the shells need to be replaced I normally would recommend sending gauges to someone who specialises in Suzuki GT750 gauge repair such as Allan Tucker in Barbados. Allan calibrates the repaired gauges so they read correctly, and when he is finished with them they both look and work better than when they first left the factory.
For this set however, I decided to do them myself as if they looked too good it would detract from the oily rag theme. I have calibrated them so that the speedometer at least is correct at 60mph, and the tachometer likewise reads close to actual. For the next two GT750 rebuilds which follow this one, I have two sets of gauges which will be fully restored by Allan as both bikes will be full nut and bolt restorations.
The rubber lamp sockets in the base of the speedometer and tachometer perish with age – luckily I had a few extras. At first glance, the wires seem to be sealed into the sockets as a part of the mould manufacturing process, but in fact they just have a dab of rubber cement to seal out the weather. This can be removed and I used a set of pull wires to pull in a socket with the right colour code wires.
I recovered the seat myself using a cover
from PitReplica in Thailand. I’ve used their covers quite a few times now, and so far am happy with them. The seat pan was rough, but I MIG-welded in a few patches and had the pan powdercoated. While I re-used the old foam, I did add a thin layer to both the top and the bottom of the foam just to add a bit of shape. The stainless steel trim was just cleaned up and re-secured to the pan. Fill installation kits for the trim are available from several places – I bought mine from HVC Cycle in the USA, who also sell replacement foam and fibreglass seat pans.
With all the niggly bits finally sorted, I put everything back together for what I hoped was the last time and rolled the bike out of the workshop for the best part of any build – that first start of the engine! This was almost anti-climactic, as the engine fired up ‘on the button’ and sounded very healthy indeed. All good… other than all the oil dripping out the weep hole on the water pump cover. This weep hole is connected via a drain line to the water pump, and vents either coolant or oil depending on which seal on the water pump fails. At first I was concerned that the small plastic drain line itself had cracked; they are getting to be a bit ancient now after all. If that had been the problem, then the only way to repair it would have been to pull the engine and tear it down again completely as one end of the drain line is located under the shifter drum, which is under the transmission.
Luckily I noticed that the oil was only dripping when the engine had fully warmed up, so I decided to first pull the water pump and double check the top oil seal. This I found to be in three pieces and so not sealing at all! After replacing the seal and then very carefully reassembling the water pump before reinstalling it, everything tested OK and the engine was oil-tight.
As I always do, I collected together a tool kit as would have been supplied with the machine when sold. With full restorations I have the tools replated, but haven’t done so in this case. The tools themselves actually are more useful than one would guess, and it is always a good idea to travel with a few extra bits and pieces.
Last summer I put about 2000 miles on my imitation barn find bike and, other than a few niggles, I’m pleased with how it is working. The front drum brake is actually better than I had expected, and the steering feels lighter to me than the disc-braked models. Now that the engine has a few miles on it, comfortably cruising at the legal limit around 65mph, with the occasional hooligan moments at higher
speeds, is no problem at all. While the front forks work well, I do need to do something about the ‘spring holders’ at the rear, as at least some dampening would be nice to have. I expect I will likely install a set of IKON replacements at some point as they look like the originals, they work well and I’ve used them on several other GT750s I own.
The reaction to this bike is sometimes entertaining. The cost of the rebuild was about $6000 CDN (roughly £3500), which is more than I could sell it for here in Canada, but it is hard to see where the money was spent as very little on the bike is shiny. I’ve actually had a number of people ask me when I plan to restore the bike as they think it looks terrible. I just smile and tell them it will be a future project. I’ve also had a number of people tell me they love the purple colour, which only proves to me that there is no accounting for taste. But the best part is that I’ve also had quite a few people compliment me on not having restored the bike, as it is ‘only original once’. Little do they know! Next on the bench is the first of the consecutively numbered 1972 GT750s: the fun continues…