5 replies to this topic

[Adam]

just fited boysen reads . wat would be a average setting on the air screw on carb. and does the mixture change any info would be cool chearssssssssssssssssssssssssssssssssss

[JSE]

Adam, on Jan 31 2008, 04:14 PM, said:

just fited boysen reads . wat would be a average setting on the air screw on carb. and does the mixture change any info would be cool chearssssssssssssssssssssssssssssssssss

Any setting for a fuel or air screw is really just a starting point to fine-tune the idle and off-idle response and varies with each engine and ambient weather conditions. Probably start at 2.5 turns from lightly bottomed out and (with a warmed up engine) quickly blip the throttle on/off and turn it in or out to get the best response. Remember a fuel screw goes out to richen the mixture and an air screw goes in to richen the mixture. Looking at the side of the carb, a fuel screw will be on the left side of the idle speed adjustment screw in the center of the carb body (near the manifold) and an air screw will be on the right (on the airbox boot side).

Jon

[Nigel Dabster]

Adam, on Jan 31 2008, 10:14 PM, said:

just fited boysen reads . wat would be a average setting on the air screw on carb. and does the mixture change any info would be cool chearssssssssssssssssssssssssssssssssss

Kehin or dellorto? Rev 3 as profile or gas gas what cc?

Boysen shouldn't change jet size much if at all, never did with mine.

Edited by Nigel Dabster, 01 February 2008 - 06:26 AM.

[JSE]

Nigel Dabster, on Feb 1 2008, 12:23 AM, said:

Kehin or dellorto? Rev 3 as profile or gas gas what cc?

Boysen shouldn't change jet size much if at all, never did with mine.

Me too, I never had to change jet sizes when I switched to Boyesens either (which I have in all my bikes). Usually a fuel/air screw change did it. I forgot to mention my observations on where the fuel/air screw were for a Gas Gas, with the carb screws on the left side of the carb. The advice as to which side (airbox or carb boot) should be accurate, wherever the carb is located. According to the profile, it's a Beta with a Mikuni carb, and I don't think he'll need to change jets unless his jetting if off to start with.

Jon

[Nigel Dabster]

As a generality here in the uk the need for jetting is very unusual, except with 125cc tuned bikes, the rest are usually near?

[JSE]

Nigel Dabster, on Feb 1 2008, 11:08 AM, said:

As a generality here in the uk the need for jetting is very unusual, except with 125cc tuned bikes, the rest are usually near?

I think you're right. The VM Mikuni pilots in the lower numbers run in half sizes so you can usually get the pilot circuit spot on, and they also seem to have a fairly wide range of adjustment with the fuel screw due to the pilot circuit design so I would guess the Boyesens wouldn't need a pilot change, just a fuel screw adjustment.

Jon