'75 suzuki gt250...Buzzing around the block

Re: '75 suzuki gt250

I did port match it, and turned out pretty well:

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I polished the other head, redid the timing on the engine and popped it back in the bike. A few more days and I'll be able to start it up again. As a time frame, I see a month or less for completion for the fairing. I'm still a little leary on the expansion pipes. I love the reliability of the bike. However, I know how to jet the carbs and do the plug chops so there should be no reason why it would fail me. that and the amazing sound and power I'll be able to get from them. I'm used to working with dellorto carbs and not mikunis. It has 112.5 jets in it right now. Where would be a safe starting point? Because I'm not altering the ports or adding a larger carb, I see maybe 140s and work my way down? Rear sets will probably be after the exhaust. Thanks, Joe
 
Re: '75 suzuki gt250

I haven't made any progress on the fairing, but everytime I saw my seat I knew I needed to do something with it. I liked the technique of using the rear of a gas tank to make the rear cowl. I stopped by my local vintage bike parts guy "big jim" and I picked up a honda tank for free. It was rusted on the inside beyond usability and the rear of it was rusted out. What I really liked about this tank is how closely it resembles the actual tank. It also was a close color match. Heres a few pics of where I was and where I'm at.

Here's where I cut the tank


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I cleaned up the edge and added a plate to the front. Did I mention I can tig weld?

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Heres the stock seat pan and where I was to cut it

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and how it looks on the bike

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I'll be working on the padding tomorrow, should turn out nice. Thanks, Joe
 
Re: '75 suzuki gt250

I did some dimensioning on the expansion pipes. From what I could gather, they should have a theororetical peak hp around 5,880 rpm. The convergent cone is long and tapered, so the powerband is going to be larger and more broad. The angles of the rest of the pipe suggest the same, that the pipes are going to be a tame and drivable machine with a good power boost. I did more work on the seat, and should have it covered by tomorrow night and bring up pics of it completed. On a side note, does anyone have the port timing specs on the gt250? I'm specifically looking for the exhaust duration. From what gordon jennings has told me, 160-170 degrees is usable, and above that the powerband gets more and more narrow. I'm assuming suzuki kept the port timing tame, so I did my calculations at 170 degrees. Thanks, Joe
 
Re: '75 suzuki gt250

I've gotten farther on the seat. I smoothed out and filled in some large holes (rust) and took a look at the bike again. I've seen many cafe bikes with the rear fender removed, but never thought to do it on my bike. Well, it really turned out nice and I welded up another bracked to mount my license plate and brake light. I also thought about the brakelight, and I like how this one looks, plus its free. Today, I'm going to modify the seat more. You can see a large gap in the front of the seatpan. This was because of the large hump in the metal I couldn't work around. I cut it up, flattened it, and welded it back together. I'm going to re-do the bottom seat so it will now extend to the tank and look much better. Expect this project to start to pick up, I've got much more time to work on it now. Thanks, Joe

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Re: '75 suzuki gt250

I finished the seat cover and more of the bondo work. Next week I should be able to pick up a second set of exhausts to swap headers with the expansion pipes. I went back to the fairing windshield plug and put a layer of epoxy on it. Hopefully next week I can get to the vaccuum form guy and pull a few pieces off of it and finally finish up the fairing. Pics as always. Thanks, Joe

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Re: '75 suzuki gt250

+1!

I might have missed it, but what kinda color scheme are you doing on this? I really liked how the original paint looked on your bumpstop for some reason
 
Re: '75 suzuki gt250

I'm going to keep the original paint on the tank and sidecovers and paint the bumpstop and fairing the "aztec gold". I like the weathered and used look of the original paint, it gives the bike character. However, I'm not sure yet on how well the new paint is going to look with the old. Thanks, Joe
 
Re: '75 suzuki gt250

Heres a quick ms paint of how I plan on having it look. Panzaa, is this what you were thinking of? I already have a good selection of klotz decals for it, along with a few other performance brand decals.

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Re: '75 suzuki gt250

Rearsets anyone? I plan on running the drum brake arm up top and use a ss rod to connect it. I think it'll look cleaner and more organized. Unfortunetly, I lost my cord to my camera so no pics of it attached to the bike. The rearset is at the correct height and length for me, a custom fit that will make it much more comfortable to ride now that it has both the clipons and the shortened seat. I picked up the pegs for $9 and the rest so far is 1/2" aluminum stock I have. The arm is machined down to .350" and I kept the mount at 1/2". I have mounted it on the bike to ensure there will be no flex, which there isn't. I also used the two bolts that hold on the original pegs into the new design so there isn't any extra parts and should look partially original and flowing. Thanks, Joe

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Re: '75 suzuki gt250

Cant wait to see the rearsets on the bike. Those are gonna look sweet!
 
Re: '75 suzuki gt250

I have this saturday off. I'm picking up a set of stock exhausts to steal the headers off and weld them onto the expansion pipes. I'm also gonna grab another oil pump. I started up the bike and threw out tons of smoke. Even after fully warmed up and ran it around, it never cleared out. I replaced the crankcase seals last summer, but I put in fresh ones again just incase. Everything seems to be normal, and when I give it full throttle, it clears for a bit. Any less, its just loading up and can't hold an idle, even with the screws all the way in. It also drips 2 stroke oil out of the headers and has the distinct 2 stroke smell, nothing like when it was burning tranny oil last year. The next logical step is the oil pump is dumping too much oil in the engine, and is an easy fix. I'll be able to get the other rearset done, and focus on the pipes and rearset linkages on saturday. In the next couple weeks, I'll be able to get the windshield vaccumformed, as the owner is swamped with business. Thanks for the kind words, joe
 
Re: '75 suzuki gt250

Looks good that seat turned out great. I don't know how well the new paint will look with your old paint. I guess if it looks bad you can always freshen up the tank later. Keep it up.
 
Re: '75 suzuki gt250

I couldn't get away from the bike so I worked on the brake side linkage. I got pretty far, but I still need to get a few more tapered bolts and lathe up a piece for the brake drum lever. Overall though, it should work out great. Thanks, Joe

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Re: '75 suzuki gt250

Just about to jump into the two-stroke game myself and came across your (amazing) post. Any updates on the bike? I'd love to see how it all turned out!

Alec Cervenka
 
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