pwk 35 nbr 6 or 5 throttle vlv

I'm using the #6 with my 36mm (RB) PWK. It works better with the BEL needle I'm using now.

I never tried a #6 with the 'stock' 35mm carb. Seeing as the several circuits easily reachable (main, pilot, AS) are leaned, I'd bet the throttle valve would work better if it was leaner, too.

It's not too hard to spend $75 on a throttle valve...so that may well be a reason it's not on the top of the list of 'things to do'.

Put in the #6. I'll bet you'll get better off idle response and smoothness of power delivery than you'll get with the #5.

I fitted a stock PWK 35mm carb to a 98 KDX220. I used a #6 slide, which worked really well on the 220. Sorry - I can't remember the needle and pilots used but the just-off-idle to mid range mixture control with the 35mm carb and #6 slide was far superior to the 33mm with #5 slide.

Check:
http://justkdx.dirtrider.net

..click on <tech tips> and <understanding jet needles>

to get your OWN decoder ring for such questions. ;)

A R1172N would equal a Keihin BGN, specs of:

1º15" taper (1 1/4º)
2.725 straight diameter
39.95 L1 (length of straight section, measured to the 'magic number' of a 2.515 diameter).

A BEL specs to:
1º15" taper
2.705 straight diameter
38.15 L1

Use your own decoder to double check all those numbers. I didn't (double check)...so my haste may be my waste.

Needle designations as 'BEL' are Keihin, the R1172N is a kawi number. Any needles you order will likely be Keihin, so the former numbering system is what you'll need. Kawi needles are proprietary, so SOME of their profiles are not available from Keihin...they are also much more expensive (like 3-4 times the bucks).

JDs needle tuning guide is an excellent tool for graphing the changes between needles. You can chart three different needles over the throttle range to see what gets richer/leaner where/how much.

Note my carb is an RB modified carb. The jetscreen has been modified somewhat that likely changes the signal at the jetblock.

The carb is a 35mm if it has not been bored. The 36mm reference is to a bored carb.

BTW..100 octane isn't doing you any good, likely doing you a DISservice unless you have increased combustion pressures due to an increased static ratio (like having the head milled). A slower burn (higher octane) isn't always a good thing. Bottom line is DON'T DO DETONATION.

Have a blast!!!

Chances are that the slide from the 1989 carb is not interchangeable with the slide off a late model 220. The older carbs had slides with a flat bottom, while the newer KDX PWK carbs have a slide with a recessed bottom.