I didn't think so. One more thing. Does anybody make a racing rotary valve for this model or do you know modifications that can be done to valve to improve performance. Also anybody make a performance pipe for this model. Told you I am looking for horsepower. And thanks for help, it is appreciated. Bob
You building the G5 for racing? Dirt or street?
I have a G5 or a pile of a G5 and am going to build it for the new AHRMA 100cc class. I have built a dozen or so Hodaka 100 and 125cc racers, a Penton or two and a couple of Yam's in the past and look forward to figuring out how to tweek a G5 motor.
I hope someone has some info on the rotary valve mods. Usually widening the port slightly is about all you can do. Which increases the amount of time the window is open so more air flows, but it only works up to a point. Usually the height of the window is fixed and shouldnt be messed with.
Looking at the valve timing specs of the G5 shows that the port opens 5 degrees later and closes 5 degrees sooner than the F5, so I am guessing that opening up the window by about 5 degrees on each side will help.
Then cleaning up (hand porting) the intake and exhaust ports to streamline and improve flow.
Also, the carbs are 19mm (I think) and going to a 24mm (from the G31M or F6) or so would be the trick IF the airflow can be increased. The trick will be to see if a larger diameter short bodied Mikuni can be fit to the motor. But with the larger carb you have to watch the air velocity in the carb doesnt get too slow with a bigger diameter carb or it gets sluggish on the botton end, and tends to load up when you come into a corner and chop the throttle quickly.
In answer to your question about a pipe, I do have a Torque Engineering pipe for the G5 that I am going to use and I see there was a G5 aftermarket pipe on ebay earlier today.
Anybody else with any ideas on hot rodding a G5 or a rotary motor I am all ears!:-D
I intend to do the same as you. Going to use in the 100cc class in AHRMA. My Rickman/honda motor is not eligible. I do have a Hodaka that I use for trials. Also in process in building 1972 wr450.
Anyway I will check out things you suggested. I will just have to keep my eye out for a pipe. Thanks for help. Bob
Late but you still might want Performance advice..
Sorry....I know your posts were a ways back but I thought you would like to know what we did to pump up the rotory valve Kawasaki's back in the day.
After market Rotory valve disc was a good one. You would have to get really lucky to find one now. But we used to take the stock Rotory Valve (RV) and use the stock Disc center piece and weld a piece of aluminum stock plate
(1/8") thick and machine it to stock dementions. The reason is the stock one would fly apart at constant high RPM's. We also used to drill holes in the carb cove to allow for more air flow to the carb. Some even removed the side cover and put an air filter directly onto the carb. There is a company who also has a Points to cdi conversion available. Good luck and feel free to contact me for any other trivia
Anyone iterested in a G31R 24mm rotary valve cover? I have a spare. It can be fitted with a G7 rotary valve assemly which can be cut to a G31M or G31R
duration. (The G31R is a roadracer version of the G31M. Same chassis, but has a longer tank, a single seat and clip on handlebars. A very fast machine for a 100cc. easily tops 180KPH with its close ratio tranny)
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