Greetings! I've been searching around for a couple of hours and have come up empty handed. Removed the GX100 clone from the Doodle Bug DB30 my dad bought and put a B&S 5hp on it. He's happy - now I need a new project to put the GX100 clone in. I have a Schwinn OCC chopper Stingray I have been carrying around for the better part of 15 years. The wife enjoyed riding around on my Warrior so much, I figured I would build her a mini bike out of the Stingray and GX100 clone engine. While the engine will easily fit in the frame without cutting, I'm worried that the little engine will not be able to pull her very well. Her only experience with mini bikes so far is on a 200cc warrior with a torque converter. Does anyone make a torque converter for the GX100 clones? I pulled the clutch off and measured the crank at 5/8". The 4 bolt holes around the crank look too small for a TAV2 or knockoff. Anybody got any suggestions? Am I stuck with just the centrifugal clutch on this engine? I have access to a lathe, mill, and TIG - I'm not above modding the heck out of a TAV2 to make it work. But if there is a TC that someone sells that will bolt on I would much rather go that route.
Doodle Bug DB30 Torque Converter?
- Thread starter RecoilFreak
- Start date
Ok, after more research it looks like a TAV2 or clone WILL bolt to the GX100. The inner bolt pattern is on a 3.625" circle, which is the bolt circle on the gx100. You can buy a 5/8" to 3/4" crankshaft adapter with taller key on ebay for $10. TAV2 clones can be had from amazon for $69 with both a 10t #40/41 and 12t #35 sprocket. Has anyone put a torque converter on a GX100 clone? I assume it would work, as the TC works off rpm, not hp.
Here's the baja 97cc sitting on the stingray frame. Looks like it grew there. Just had to remove the fuel tank. I am going to make an adapter to remount the front bicycle sprocket to the rear wheel in place of the free wheeling sprocket. The big sprocket has 44 teeth - the #35 sprocket on the TAV2 clone has 12 teeth. Works out to a 3.67:1 gear ratio. Hopefully the torque of the TC and the very light weight of the stingray make up the delta of not having a 5:1 ratio.
Sidenote: This is not a GX100 clone. It's a G100 K2 clone - a side valve flat head. Stock CR is 6.5:1. I wonder how much more nuts I can give it by milling the head?
Sidenote: This is not a GX100 clone. It's a G100 K2 clone - a side valve flat head. Stock CR is 6.5:1. I wonder how much more nuts I can give it by milling the head?
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Strig, I'm not looking for performance out of this thing. I don't want my wife to get hurt. Do you think the torque that the TC provides on the low end would be better than a centrifugal clutch? I am doing everything I can find to improve the performance of the little 97cc. I have milled the head .030" and I plan on making a dead soft copper head gasket as long as I can avoid valve to head contact. I have ported the intake and exhaust (lightly - just removing casting marks and softening the short side radius), I have built a header for it and I will be running an open element air filter. I plan to put a 19mm carb on it. I cannot find a billet flywheel or rod for it, so removing the governor is out of the question. AGK will not sell me a billet flywheel for a predator 79cc (which i have no doubt I could modify to work with this little thing), but still can't find a billet rod. Maybe I just need to make a flywheel and rod.
Ok, got the whole thing torn down and in the ultrasonic cleaner. Came out looking like new. I milled .030" off the head and checked valve and piston clearances. Ended up using the stock head gasket instead of making a copper one since tolerances were close. Did a light port/polish on the intake and exhaust ports. Built a straight pipe header I will eventually put a screw on type mower muffler in. Ended up buying a chinesium TAV2 TC off amazon along with a 5/8" to 3/4" sleeve to convert the shaft. All that's left to do is weld the engine mount plate to the bike frame, mount up the engine, source a fuel tank, hook up the throttle, and we can see if this thing will perform at all. I'll keep you posted.
I believe with the low enough gear ratio you can get away with 3hp motor. Probably at the least a 6 or 7 to one. Youll have decent take off and probably go around 25mph to 30mph just estimating. An air filter and exhaust upgrade as well as a governor delete would probably gain you some power to help move it better. A torque converter will definitely give you better low end torque in pretty much every scenario. If you want all out speed, a clutch is better. You can gear a bike down with a jackshaft and clutch as well, which will give you good torque at the expense of speed. I wanted to try the same on a mini chopper frame i have. Had a 5hp 49cc 2 stroke on it. I wanted to put 79cc predator on it with a torque converter. Gear it to go bout 20 to 25. Good luck on your project man and take care.