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DirkChecken, is that pic of the silver 750 a Suzuki GT frame with updated swingarm or a custom one? How bout the front fork system too? Do you know what brand those expansion pipes are?
Bakker; It's a Nico Bakker frame and you can bet the chambers were custom hand built considering that Nico Bakker hand built those race frames near 50 years ago.
 

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If this was 1974 and you wanted competition front forks you would be shopping for Ceriani forks and those were made in Italy. If you are shopping for competition forks now and you don't want to spend the coin on Ohlins, then you would be shopping for something Italian. Look for Italian sport bike forks and you will find the best bang for your buck they will be branded Marzocchi or Paoli or Ceriani and if you just gotta buy made in Japan, you will probably want it to say Showa on it which is actually the premium suspension brand owned by Honda. Interesting enough, all the same brands synonymous with competition trials motorcycle suspensions, which in reality is likely where all the best suspension technology was initially developed.

... what makes the difference between a really high end suspension component and a cheaper one is the number of ways you can adjust the thing. If you can independently dial or screw adjust; Compression dampening, Rebound dampening, plus spring preload it is an expensive component that lends to being adjusted to your specific riding needs. If it has a huge nitrogen reservoirs for cooling, thats perfect if you are building an endurance racer or a really heavy rider.
 

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Discussion Starter · #27 ·
Bikes look sweet DirtChecken. Keep the pics coming. 😁 Im new to the 2T motorcycle world. GURU to the Honda ATC lineup.

Who sells carb reed valve kits for these GT750's. Any recommended electronic ignition systems recommended for them?
I bought a '74 GT750 that has a locked-up engine that will move 5 degrees in rotation then locks up again. I plan to tear down and use this engine to hopefully build back to a goal of 80HP.
 

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DirkChecken, is that pic of the silver 750 a Suzuki GT frame with updated swingarm or a custom one? How bout the front fork system too? Do you know what brand those expansion pipes are?
when i do a front end swap, first thing i do is measure the bikes steering head tube length. then i find a bike that has about the same head tube length. (a junk yard will be a good place). +/- a 1/4" or so. buy the complete front- steering stem/ forks/wheel,brakes/fender etc. then go to allballs for your bearings. all this is not hard. sometimes ive had to replace the steering stem for a longer one. (longer headtube on the donner front). most jap bikes stems are welded to the lower triple tree (a problem) some are pressed in. a machine shop can help you here.
 

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Bikes look sweet DirtChecken. Keep the pics coming. 😁 Im new to the 2T motorcycle world. GURU to the Honda ATC lineup.

Who sells carb reed valve kits for these GT750's. Any recommended electronic ignition systems recommended for them?
I bought a '74 GT750 that has a locked-up engine that will move 5 degrees in rotation then locks up again. I plan to tear down and use this engine to hopefully build back to a goal of 80HP.
ive seen reed conversions on kaw triples. never on a suz gt750. could be cause the suz is water cooled and some machine/ milling must be done? reed blocks are larger then just a hole intake.?is there enough room? material on cylinders? i dont know. works tr11's where all piston port i believe. maybe teazer knows more. ive seen pics of the early (1980?) cagiva 500 gp bike, in this case they used a inline 4 yamaha gp 500 engine and fitted rotary valves to it- on top of the crank case behind the cylinders.i dont believe it made more power then the yamaha engine. point is is you want to do it , it can be done.. check horse power ignition in belguim, they sell ignitions. before you get a new one check your crank/ does it need a rebuild? theres no adjustment on the hpi ignitions for the pickups and if your crank is worn you will wreck the pickups
 

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Discussion Starter · #32 ·
Will being disassembling this locked engine sometime in December. I planned to have the crank sent out to the Triplecranks in Maryland (Charlie Cranks) or BillBune Enterprises in Minnesota. Unless somebody knows of a shop in Michigan.
 

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Seriously, look inside before you line up all the people you want to hire. You're not going to have to go to great lengths to get 80 horses out of a good running GT750 engine if you don't care how loud it is, and most of that power is going to come from your expansion chambers and intake with things like a reed valve making it produce better mid range response, aka making it more ridable.
If you are building it for world land speed record (y) you need all those guys
 

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A friend put a Mikuni carb and reed cage on a Bultaco and it worked as expected. GT750 Suzuki is basically 3 Suzuki 250cc cylinders on one crank and not a lot different. Piston port 2-stroke. You are going to need to modify the pistons to benefit from a reed valve addition, put windows in the sides of the pistons. The reed cage and adapters add length to the intake, moves the carbs back, so it pays to go with more narrow profile, larger carbs. ... lots of money.
 

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Discussion Starter · #36 ·
My idea plan for restoring the locked-up engine was for recreational riding only NOT drag, circle track or other racing. Im sure the crank (if not damaged probly needs new seals and bearings hence the crank rebuild shop). In hoping to keep up to my buddies bikes up to the speed limit of 80mph. There toys are (150+HP crotch rockets). They despise my whole love for the 2T oldschool motorcycles. (Want to prove them wrong up to a reality point). Use to own a V65 Magna 1100. That was a fast enough bike for me, but not 2 stroke.
 

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The thing that makes for a fast rider on the street is not horsepower and big horsepower on the street demands upgraded suspension, frame, wheels and brakes to handle the big horsepower engine. You won't have a problem pulling 80mph out of a 750cc 2-stroke engine, but you will have a problem making a 1970's Suzuki GT750 handle high speed really well. Most of your performance improvements after you put expansion chambers on it will not be need more horsepower related, you have to be able to put the power to the ground.

... V65 Magna was a good example of too much horses and no way to put it to ground.
 

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All those nice TR750 Suzuki' race bikes that dirk has been posting started by throwing away the stock frame, just like Suzuki did when they raced them in grand prix, you don't have that option because your VIN is on the frame and you are building on a GT750 for street. The weak links on your stock bike frame are the steering head bearing and the swingarm bushings, take it apart and see how mickey mouse the original parts are compared to the similar assemblies on a modern 150hp crotch rocket. You are going to need to upgrade the frame first and your best bang for the buck is to upgrade the rolling chassis. Once you get the thing producing 80 horses and rolling on modern tires with modern brakes, then you will notice the frame flex if that isn't upgraded somehow, those frame bearing points need to be significantly upgraded with serious bearings.
 

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TR750 frame is nothing like a street GT750 frame, TR has rigidity through triangulation all the way from the steering head back to a much longer stronger square profile swingarm as you would find on a current model dirt bike.


another jalsteve bike photo (y)

edit: jalsteve has a video posted if you want to see how much smoke and noise you might expect
 
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