CV carb tuning

[flyingace]

I was considering enrichening the jetting of the lower to mid-range of the 850's power band (2000-4000 RPM) since it seems a little starved for fuel there. The bike is box stock, and I want to leave it that way, so I only want to change carb jet and needle settings.

First, is there a way to richen up the midrange without a jet kit? Either way, what would be the best and/or easiest carb changes to make?

Thanks.
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[Motoplas]

Try putting washers underneath the needle, this will give more fuel in the mid range and a little more on top.

Motoplas

[knotzilla]

You should do a plug check first. Maybe the mixture is too rich right now. Ted

[Dink]

The rev range you mention (2K-4K rpm) is covered more by the idle mixture and progression holes; at 4K you are only just starting to draw off the needle jet, so playing with spacing the needle wont help.
Have you made sure of cleanliness?? especially the progression holes??
As previously suggested do a "plug chop: in the rev range you are concerned about to find out if it is indeed lean or is actually rich.

Dink

[rustybronco]

http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html

[flyingace]

The bike runs very well and all the plugs are light tan to white. The bike acclerates cleanly, but seems to 'kick in' at just over 4K. Until that point, it just seems a little fuel starved. I've read other threads where owners have richened up the mixture at these RPMs, but I can't find that thread.

Bronco - thanks for the link.

Dink, would not raising the needle cause the carb to start drawing from the main sooner (less throttle)?

[Dink]

The bike runs very well and all the plugs are light tan to white. The bike acclerates cleanly, but seems to 'kick in' at just over 4K. Until that point, it just seems a little fuel starved. I've read other threads where owners have richened up the mixture at these RPMs, but I can't find that thread.

Bronco - thanks for the link.

Dink, would not raising the needle cause the carb to start drawing from the main sooner (less throttle)?

If the plugs are white to light tan it is a little lean, so by all means raise the needles. BTW no amount of raising the needles will effect the revs that the bike draws from, only the mixture.

Dink

[flyingace]

Thanks.
What about just installing the next larger size main jet?

[Motoplas]

Main jet only has an influence on full throttle.
Try the needle washer thing first, I think you may be suprised.
Motoplas