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?

Real Classic - - News - Pho­tos by Ian R Sandy

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…

Oc­ca­sion­ally known in some mar­kets as the ‘wa­ter buf­falo’, Ian’s Suzuki meets some … buf­falo Above: The orig­i­nal early swing­ing arm bush­ings were steel (left), and the re­place­ments are fi­bre Be­low: The ‘Man-genta’ tin and trim in­stalled on the rolling...

It’s That Mo­ment. Time to roll the bike out and fire it up

Left: The gauge lamp socket and the area where the wires are sealed with rub­ber ce­ment Be­low: New plas­tic shells in­stalled and the clocks cleaned up and cal­i­brated

Ian re­placed the orig­i­nal volt­age reg­u­la­tor with a unit from Ore­gon Mo­tor­cy­cle Parts. They have a small pot which al­lows you to ad­just the charg­ing volt­age. Rec­om­mended

The plas­tic gauge/clock hous­ings are usu­ally cracked, al­low­ing mois­ture to get in­side the gauges. Suzuki switched to metal hous­ings for the 1973 model year

Be­low: The cen­tre wiring har­ness laid out. Still a few things to sort, but the burned out wire has been re­placed.

Above: The up­per fork yoke on the drum-braked 1972 GT750 is wider than that used on later dis­cbraked mod­els. As the flange where the up­per fork pinch bolts of­ten cracks you need to take care when look­ing for a re­place­ment

In­side the Ket­tle’s ex­hausts: these pho­tos from Richard Nowsen show the in­ter­nal baf­fles which of­ten come loose, as well as the sound-dead­en­ing mesh

The set of pipes Ian chose to use for his ‘un­re­stored’ re­build project. Not ex­actly ‘show qual­ity’ but the baf­fles are sound and they ac­tu­ally buffed up not too badly

oil seal on the A mi­nor prob­lem: the up­per At least it didn’t wa­ter pump had failed. strip… ne­ces­si­tate an en­tire en­gine Ian al­ways as­sem­bles a full tool kit as orig­i­nally sup­plied by the fac­tory Fol­low more of Ian’s ex­ploits with his next project at...

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