250 Mag Jetting Specs

Hey Guys: Can anyone get me in the jetting ballpark for a 250 Mag with a Circle F snail pipe and a Bing 54?

Thanks a million
Marc

First: Does the bike run? if so what problems are you having and at what throttle openings are they occurring at? (if not, I can tell you the original jetting that came stock on the bike if that's what you want.)
Second: Are you using the stock carb. and jetting? stock air filter? is the engine modified other then the pipe? what fuel/oil ratio are you using?

The carb is stock, with a 195 main, 35 pilot, 2.85 needle jet, and the clip is on the bottom groove (needle highest). Floats are set properly. No porting that I know of. 40:1 premix. The bike starts easily, then is sort of pig through 1/4 - 3/4 throttle. There is a definite hit in the power as it comes on the pipe, and then it runs kind of ragged. It feels as though there is more there. The plug appears dark, but I'm not sure I've done a proper plug test. I'm thinking I ought to drop the main (how much?), but what to do about the mid range?
Thanks Marc

That almost sounds like jetting for a non-reed valve engine except for the main jet. Right off the bat I see your needle jet is too small, and that would be most of your trouble in the 1/4-3/4 range. I do not have my Bing book at hand but should be more like a 3.14 or 3.16 needle jet. You have a #53 slide and a 401 needle right? Also check the float pivot pin for wear when you recheck the float level. Remember to do one change at a time when it comes to jetting. Let me find my Bing manual and we will see if we can get it spot on.

Opps, my mistake, They did not make the big carb changes until 75, so it would be a #1 slide and 281 needle. let me check to see what needle jets work with the 281 needle and get back to you, also did you check the needle for wear?

Yeah, the needle and needle jet look OK. Thanks!