Will'smotobikes19
Well-Known Member
You could port a weedwacker engine and put a little expansion chamber on it for more power. Friction drive is probably best for under 49cc engines. Chainsaw would be better though.
You could port a weedwacker engine and put a little expansion chamber on it for more power. Friction drive is probably best for under 49cc engines. Chainsaw would be better though.
Ya all you need is a dremel and some sandpaper. Some of those engines have a divider in the middle of the port you could delete but not all have it. They make little expansion chambers for the hpi baja and rc engines you could adapt. I actually want to that to see if it actually helps the top speed or anything. I have 3 power heads and a chainsaw but they all have carb problems. I have an old 31cc ryobi that I think needs a magneto, a 25cc homelite that runs but has a bad carb and an old hedge trimmer engine that stripped the key on the flywheel. The diaphragm carbs are a pain. If they were slide carbs it would be much better. Maybe I could adapt the stock nt carbs for one of those engines, perhaps the homelite chainsaw.
A much better choice would be one of the zenoah small engines made in Japan there's one that's 31cc but is like 9hp where a weedwacker is only 1 hp. And they make clutches for them. http://www.zenoah.co.jp/int/products/hobby-engines/g320pum/
Holy batmeal beans Batman, look at that idle speed! 4k!A much better choice would be one of the zenoah small engines made in Japan there's one that's 31cc but is like 9hp where a weedwacker is only 1 hp. And they make clutches for them. http://www.zenoah.co.jp/int/products/hobby-engines/g320pum/
Im not too familiar with porting, we are talking about the intake port right?
No! absolutely don't attempt to 'port' a weedeater engine!
Espcially if it's a decent model like an Echo or Tanaka. You'll either really muck up the cylinder and ruin it or cause a tuning change that ruins it's power spread. Honestly I don't know where people think you can apply China Girl engine tuning techniques to precision little weedeater engines. You'll just end up ruining what was a good running engine. The best thing you can hope for is to check the spark arrester, if so equipped, and clean the mesh screen and maybe fab a small performance aircleaner to the intake, but that will take some serious tuning skill. Weedies as a rule like RPMs and should be 'geared' conservatively. 1 and 1/8" inch diameter driver friction wheel is within the ballpark for something that might clim moderate hills with leg assist. At this engine size the engines should be bicycle assistance engines, not the primary power source.
Read this thread in MotorBicycling's DIY subforum: https://motorbicycling.com/threads/minimalist-fd.62572/
Cannonball2 builds some of the most sanitary light bike drives on any Motorized bike forum and should be an inspiration for those who want to build DIY friction drives, the engine in his thread keeps it's auto clutch working so you don't have to raise the engine off the tire at stops.
Thanks for the reply, that is exactly what’s I was looking for! I probably won’t port the engine just because of my inexperience, but if I install a small spindle it should give decently torque and a low speed. Thanks