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View Full Version : FCR 39 Carb Help Requested



Bart
02-08-2002, 07:34 AM
If anyone has a Keihin FCR 39 carb sitting around, I could use a little help.

I recently bought a FCR 39 carb. I was checking it out and removed what I believe is the slow air screw without knowing what its default setting was. The screw I am talking about is the lower left screw that gets covered up by the adaptor on the airbox side of the carb (see attached picture).

If someone could tell me how many turns out theirs is set to, I would greatly appreciate it.

Thanks in advance.

oynot400
02-08-2002, 08:18 AM
I have an extra FCR laying around I could check for you tonight. I am not for sure but isn't that just a jet and it just gets srewed in?
I will check for you anyway. ;)

Bart
02-08-2002, 08:30 AM
I thought it was a jet at first too. When I removed it, there was a spring behind it and it had no jet number stamped on it. That's when I realized I probably just screwed up.

I did some searching on the web. The sight

http://www.lifenet.com/brm/carbkei.htm

describes that it could be either a slow air jet OR a slow air screw. If I can find someone with either the screw setting or the jet size, I can use the info at that site to get me at least close. It's hard enough for me to adjust the fuel jets (main and pilot) let alone air jets as well.

Once again, any help you can provide would be greatly appreciated.

oynot400
02-08-2002, 09:09 AM
Wow there is alot of info at that site! :eek:
I will let you know tonight what I find out.;)

oynot400
02-08-2002, 03:51 PM
Fred,
I just got home, screw in the air jet all the way. Then back out 1-1/4 turns. That should get you pretty close to what it should be.
Just a note, you might want to get some vent tubing for your carb. I would hate to see anything happen to that carb of yours. :D
Hope this helps, let me know if you need any more help.

Bart
02-09-2002, 06:35 AM
Thanks for the help. I'll let you know if I run into any more problems.

Time to go riding.