GT750 into RD350 Hybrid

[ajb235]

Hell0, I'm new to the forum but looking for some advice.

I have RD350YPVS with Suzuki RGV forks and swinging arm/suspension. I would like to put a GT750 engine in the frame, with a target of 100RWHP, and maybe fuel injection. Bike currently weighs in at 144 kg, but this will increase with the bigger motor.
Has anyone done this?
Looks like I will have to extend the wheelbase by a few inches by adding some length to the frame to get the 750 in.

Any advice appreciated

Thanks
Jim

[Alan H]

I think you'll need a stronger frame. The kettle engine weighs as much as a small planet.

[BAZ]

85 kg good luck and post pictures

[CJB]

100 horses at the rear wheel is pushing it, even the factory TR750's (Barry Sheene Daytona) only managed just over 100 hp. Other specialist tuners eg Ocelot managed to extract about 140hp but for an awful lot of money involving dry clutches, magnesium castings etc and as alluded to above the GT engine is no lightweight. It would probably be cheaper to get 100hp from the original YPVS engine, you'd definitely get a better power to weight ratio.

Would love to see some pictures though.

Chris

[ajb235]

OK, thanks for those first few replies, keep it coming!

I will save weight by removing the starter motor, and generator, and run a self generating igntion system. I also want to fit reed valves which will allow me to use more radical port timings.

Any idea how much weight the generator(with shortened crankshaft) and starter motor+gearing would save?

JIm

[mizzytheman]

Hi Jim,

And welcome to the forum. Not sure about using an LC frame to house even a lighter GT750 engine but, hey, go for it. If you're looking to lighten the motor and see how much weight you can save check these guys out. http://www.bdkraceeng.co.uk/TR750s.html

Good luck with the project and keep the pictures coming.

Regards

Martin

[garry55]

I would seriously re-consider your choice of frame. If you are aiming to extract 100hp out of the motor, surely you want it to be able to handle that power too?
Adding "a few inches" to the frame will make for even worse handling.
Would bring a whole new dimension to the term "flexi-flyer" though !

[ajb235]

Thanks for your helpful comments.
The main reason for this project is to have the 3 cylinder Suzuki GT750 2 stroke engine howling through a 3:1 pipe, this sound is amazing. And with the smooth power delivery and potential to tune up to 100BHP, loads of torque mid range,there are many good things about this engine.

However, the bike must be safe for me to ride, and safe for everyone else on the road, so I have to consider:
1.the design and strength of the existing Yamaha frame
2.the increased weight and power of the GT750 engine in the frame,increases the stress on all components and welds.
3.whether the strength of the Yamaha frame will be compromised by additional welding and joints required to lengthen it.
4.whether my RGV250 forks and swinging arm are strong enough. I would certainly have to uprate the springs.

On balance, I think I will use the GT750 frame.
It may be heavy, but I can lighten it by removing unwanted brackets and lugs
It may be flexible under increased power/torque but I could stiffen it up.
I could improve it with a better swinging arm, and bearings.
I could improve it by changing the front forks to say GSXR or Hyabusa.

I had a look at the BDK site, there's lots of weight saving goodies for the engine on there.


So still a very interesting project, and it keeps my Yamaha in one piece for future enjoyment , or I could sell the Yam and put the money towards some Titanium bolts and lightweight engine covers/dry clutch etc.for the GT...

Thanks again, I will post progress photos etc.


Jim

[CJB]

Some interesting pictures and porting diagrams here, most of the high power specials use non Suzuki frames, Sealey, Harris etc. I don't think that's by accident (maybe to prevent one!!) Look especially at the factory "race" bulletin as that gives the porting and other changes necessary to make the stock engine a racer.

http://www.ozebook.com/compendium/tr750/tr750.htm

[fireone]

Hi Jim, I also am building a 350 lc hybred been looking at a 3 cylinder banshee crankcases, barrels and head from the states , appros 730 cc. They also do a 4 cylinder ! Thanks DAVE G.