Friday, May 1, 2009

Operation BFW

My wife has always been happy with the top speed of her moped, and always more concerned about how quickly it accelerates and how well it climbs hills. That is, until recently, when she got blasted by Rosanna as the two of them were riding somewhere. Now, she has charged me with making her moped faster, without losing any acceleration, getting any louder or going over 50cc. What a pickle! I ordered up a KSTAR 50cc, to find that the boost port in the piston doesn't actually do anything, which was kind of funny, and although the cylinder looked nice, it took much to long to wind all the way out, with a crawl from a stop even with my two speed. So perhaps the port timing needed some more adjustment or some such thing, but even with a high-compression head, it wasn't acceptable. I had been running a #7 High Torque stock cylinder with a single ring piston, and I noticed the ring had begun to crack a little and there was significant blowby on the top. So I dug deep into my box-o-stock cylinders and found a precious gem. A #1 HT cylinder with matching piston and rings. With this cyilinder, I think I've found the right combination. With the HC head, it zips right off the line and shifts around 18mph, but doesn't seem to have that lag that the last two cylinders had when shifting into second, it just powers on up to 30+. I should GPS the bike, but it does pretty well with me on it, so even with my lovely BFW it should still push itself along.

I also spent an hour yesterday trying to track down some 1" ID rubber hose with no success, so I settled for 1" ID vinyl tubing. I guess that's okay, although it won't hold up to gas as well as rubber, it will at least be kind of neat to see the flow between spigot carb and intake...

1 comment:

Ian T said...

they have 1" at the carquest on the north side of the fremont bridge, i just bought some. I have a foot or so extra if that helps you at all.