Keihin FCR jetting tips

[Greg in Oz]

OK, here's hoping I get this right in my first post. I'm trying to get the jetting right on my 2000 model FC501 Husaberg. I had a 41mm FCR lying around and thought I'd give it a run on the berger. After a few hiccups I managed to find a needle that seems to work, these carbs have a massive range of them and it's too expensive to buy a bunch to try. I'm using the accessory richer needle from the 426 Yam. Its an OBDVS. With ELF Atmo Rally race fuel I'm running a 190 main , 52 pilot and the needle in the 2nd from bottom notch. The thing is running OK but when I tried 3rd notch from bottom it developed a huge mid-range flat spot. So I figure I need to maybe try a richer needle. Question is do I stay with the same length/taper etc. To work this out I really need to know if the leanness is across the throttle range or only in the middle. So here's the query. Is there a way of doing mixture readings by checking the plug colour at other than full throttle openings?

 

[Kramer]

No, the spark plug is really only good for full throttle. The best thing will be to critically ride and try to feel how it runs at the diff. throttle settings.

For FCR tuning, this is the most detailed description I've seen.

White Bros. also used to have a decent write up on FCR's too.

Boy, does that sound redundant sounding:o

 

[SFO]

FCR Husaberg- a match made in heaven

Try writing Dale Lineaweaver an email.
[email protected]
He is/was running the FCR carb on his Husabergs.
He has got it dialed in.
Tell 'em Big Bill sent ya.