Suzuki 2 Strokes

Ever since I graduated college almost two years ago and parted with my introduction to big Japanese road-bikes (a '78 Kz1000 that had survived 30,000+ miles of abuse in the hands of an un-attentive owner), I've had a need to fill its place. So out went the add on CL looking for a project bike for the winter. The only response came from a guy with this 1975 Gt750 with about as many miles as the Kz. I'll be honest, I didn't know too much about the bike but, the more I read up on it, the more it drew me in. So a few weeks ago I brought it home (actually to the hangar where I work. Big thanks to my boss for allowing me to work on it in a fully stocked aircraft hangar!). If my truck could give birth, it would have been this bike.



First things first. A good bath. The bike had been stored in a garage but had obviously been sitting a bit. Apparently the previous owner had it kitted with a cafe fairing and the currently-fitted exhaust and was try to return it to stock form but got a little in over his head. I also got the original 3-4 which looks to be in good shape!



After a quick look-over too see what I'd gotten myself into. The only thing that really worried me was a broken-off drill bit where an exhaust bolt should be. Yikes! I hate removing drill bits. People need to go easy on the gorilla torque! Oh well. Note the angle of the exhaust bracket in the below pic.



The previous owner didn't even use this guy as a selling point. Hurray electronic ignition!



And here's the rest of the stuff that came with. Sorry for the blurry picture. I was having some post-purchase shakes.



Thats all for now. More to come as progress is made. I've got the carbs cleaned and the rats-nest wiring somewhat sorted out. Pictures of that later. My overall plan is to get the bike running. See what operational items need replacement/overhaul, then tear it down and give it a good cosmetic thrashing. I joined this forum to share the joy of seeing a bike come back to life but also to get advice/suggestions. I'd love to hear from everyone as I go along!

Congrats. It took a lot of years riding a lot of different motorcycles to come to these GT's in the past year or so. I have owned and ridden nearly every type of motorcycle. None, I have ever seen or owned compare to the coolness and fun factor of the 70's era two strokes. You're kinda lucky. But, kinda not. That you've run across these bikes so early. Having not ridden very long or owned different types. That fact, will likely spoil you. Lol !

Got some work done on the exhaust and air filter over the last few days. Mostly just cleaning. Some nice evening sun and blue grass courtesy of the Steeldrivers make for a great work atmosphere.



I did have a few questions for people out there. Can someone explain the fiber wrapped at the end of the baffle? Purpose? Looks like it is held together by safety-wire. Not sure if that's Mr. Suzuki work or the previous owner.



Tonight I was able to install the original 3-4 exhaust on the bike and it looks pretty good! How loose should the exhaust be? When I grab the small exhausts and give them a little wiggle, there's some movement... not a lot. All the bolts are snugged, just not sure if I'm missing something seeing that I'm re-assembling something I didn't take apart. It may be designed to have a little give to absorb some vibration... not sure.

Baffles and loose lowers are normal. The stuff around the ends you are referring to is used for baffling the sound and yes it is held together by wire from the factory. Yours however, is slowly coming apart. No big deal. Just rewire it. All lowers on these bikes jiggle a little do to flimsy mounting tabs. Especially when the bike is started.

Nice find. Was it from Gordon L. by any chance?

As PJ mentioned, stock baffles are wrapped in fiberglass wadding and it's held in place with safety wire. It's designed to absorb some of the noise not attenuated by the mechanical baffle. You can but replacement two stroke wrap/baffle material from a dealer or on-line. One pack will be more than enough for all 4 baffle tubes. Some guys run their baffles without thjat material, but I prefer to keep it.

The engine is rubber mounted and so are the exhausts. Side pipes are one piece, so they don't move much, but the centers slide over the header pipe with rubber sleeves and that arrangement allows a small amount of play. The outers should not be solid though. There should be a small amount of wriggle room.

The pipes that were on it are JEMCO and there should be a market for those if you want to let them go. For example, I borrowed a set from someone here on the board and at some point in time I'll have to return them and buy a set.

tz375 wrote:Nice find. Was it from Gordon L. by any chance?

As PJ mentioned, stock baffles are wrapped in fiberglass wadding and it's held in place with safety wire. It's designed to absorb some of the noise not attenuated by the mechanical baffle. You can but replacement two stroke wrap/baffle material from a dealer or on-line. One pack will be more than enough for all 4 baffle tubes. Some guys run their baffles without thjat material, but I prefer to keep it.

The engine is rubber mounted and so are the exhausts. Side pipes are one piece, so they don't move much, but the centers slide over the header pipe with rubber sleeves and that arrangement allows a small amount of play. The outers should not be solid though. There should be a small amount of wriggle room.

The pipes that were on it are JEMCO and there should be a market for those if you want to let them go. For example, I borrowed a set from someone here on the board and at some point in time I'll have to return them and buy a set.

No, the previous owner was not a Gordon. How do you compare the stock 3-4 and the Jemco?

Toast wrote:
No, the previous owner was not a Gordon. How do you compare the stock 3-4 and the Jemco?

One sounds good and one sounds bada$$

Old School wrote:

Toast wrote:
No, the previous owner was not a Gordon. How do you compare the stock 3-4 and the Jemco?

One sounds good and one sounds bada$$

Objectively: JEMCo weigh a lot less than stock and that improves handling, braking and acceleration somewhat. Jemco pipes if jetted correctly make less power than stock below about 5500 RPM and more above that point (compared to stock pipes). If you regularly run your bike from 5500 to 7500, Jemco will get you there faster. If you ride mainly below 5500, stock pipes are smoother and quieter and will get you there as fast as JEMCo's or faster.

Subjectively: One sounds "better" and one looks better. Which is which is a personal thing. JEMCO make less power down low and more up high, so when you accelerate through that transition point, you really feel a significant change in power that makes the bike feel more powerful that it is. Half of that is a real power increase and the other half is the lower power at low revs that makes for the change that the rider feels.

I agree with Richard with his explanation. If you are after the stock look, by all means the stock exhaust is the way to go.

For performance and sound I like the Jemco's. That said I have found that the single biggest performance gain that I have seen is gearing. These GT's (and mainly the later ones) are way over geared if you are wanting any kind of straight line performance. After my first ride on a Buffalo, I instantly had this feeling. For mostly around town riding with maybe a little country crusing, a lower gear will really wake the bike up.

Hey guys, thanks for the advice so far. So I'm thinking of checking the oil pump and lines tomorrow to make sure they are doing their jobs. Whats the best way to do this? If there's a good explanation somewhere on this forum (I bet there is) maybe just shoot me the link. Thanks!

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There are others including the OIL threads.

Old School wrote:I agree with Richard with his explanation. If you are after the stock look, by all means the stock exhaust is the way to go.

For performance and sound I like the Jemco's. That said I have found that the single biggest performance gain that I have seen is gearing. These GT's (and mainly the later ones) are way over geared if you are wanting any kind of straight line performance. After my first ride on a Buffalo, I instantly had this feeling. For mostly around town riding with maybe a little country crusing, a lower gear will really wake the bike up.

Absolutely, the best modification anyone can do to any bike. Especially, a two stroke that does not make much power in the low to mid rpm range. All bikes are geared high from factories. The GT 750's are ridiculous.

pearljam724 wrote:

Old School wrote:I agree with Richard with his explanation. If you are after the stock look, by all means the stock exhaust is the way to go.

For performance and sound I like the Jemco's. That said I have found that the single biggest performance gain that I have seen is gearing. These GT's (and mainly the later ones) are way over geared if you are wanting any kind of straight line performance. After my first ride on a Buffalo, I instantly had this feeling. For mostly around town riding with maybe a little country crusing, a lower gear will really wake the bike up.

Absolutely, the best modification anyone can do to any bike. Especially, a two stroke that does not make much power in the low to mid rpm range. All bikes are geared high from factories. The GT 750's are ridiculous.

How many teeth for the front and back sprockets would you recommend?

Mine came with 16/43 (standard for the 1975 M model). I felt it was too tall so I changed out the front for a 15 and I like it a lot better.

It depends on your riding style. I have one that is geared 15 -50, it is basically geared 1 1/2 down (in the front) from stock. I am working on this bike to see how quick I can go at the track, it may be a little low for prolonged highway use.

As RD posted most later models came with 16 - 43, and simply dropping one tooth in the front to a 15 will bring it to life.