Wow so it's been a long time since I've posted on here, I haven't had much of a chance to do anything to the bike for a while but I recently actually took it to the track for the first time.
I've only got a small yard at home so I'd been riding it around a little and it was working just fine but at broardy it wouldn't open past half throttle, anyway I brought it home and was mucking around for ages with needle clip positions etc trying to get some improvement, absolutely nothing, not to mention the thing was leaking like a sieve.
The carb I have fitted is this one which is a genuine CV mikinu from a Yamaha FZR250.
It wasn't until I visited a FZR forum to see if there was anything I missed setting it up that I saw a pic of it mounted.
This is a downdraft carb, no wonder it wasn't working haha, that little line to the left of the fuel inlet is meant to be vertical, not horizontal. I'm amazed it ran at all!
Anyway I re-mounted it (at the expense of the battery holder, the bike doesn't have a battery at the moment anyway) and it now revs all the way but it sounds way too lean.
So the standard main jet in these is a 72.5. These were ganged in a group of 4 so this carb drove a 62.5cc pot but the FZR revved to 20k RPM. So I'm trying to figure out what would be a good starting point for a main jet for my stock 125cc lifan.
I'm planning on taking one of the other jets from the gang and drilling it out with a 1mm bit to give me a #100 just to see if it makes any difference, but before I order anything I'd like a rough estimate.
Thanks!