Jetting Help

if you can't get a leaner needle you could try lowering the fuel level in the bowl by a couple mm's.
That will make everything a bit leaner, you might have to go to a bigger main to compensate for top end mixture.

You mention there are other guys using this carb on the same bike. Are you using the same needles and jets, and if so, are there other differences between their bikes and yours (exhaust, air filter, etc.)? Ed

The PWK is a very common carb on 2 stroke MX bikes, and IMO isn't too big for a 400. If you are on the hunt for a leaner mid-range and the needle is hard to find, consider going to a smaller, leaner needle-jet... There is more than 1 way to skin a cat! Including putting his head in a boot jack and pulling his tail really hard!!!! :woohoo:

Have a look at www.jetsrus.com/a_jets_by_carburetor_typ..._keihin_N427-48.html they seem to have everything you could possibly want for needle info. If you had a way of measuring your existing needle, you could compare it to their chart and make an educated choice. I have used jetsrus.com in the past for my oddball carb on my flattracker and they have allways been a great resource. Paul

Regarding the ID on your needle N0LB, are you sure it is an O (oh) or a zero. Could it be instead a Q (que). As it appears there are no listings for that ID, but there are for some with a Q.

Thanks for all the awesome input guys. I ended up lowing my float level and it made a drastic difference! In fact after leaning out my jets so much, and then lowering my float level, I am a little too lean now

Guess it's time to jet it up and try to find that sweet spot I've been looking for all this time.

If not already done, would perform the "clear tube test" on each carb to assure that
the fuel level is within specs.

A specific dry measured float height is not the objective

The objective is achieving correct fuel level when the carbs are being supplied with fuel.
This is referred to as the "service" fuel level.

Good Fortune!

Patton wrote: If not already done, would perform the clear tube test on each carb to assure that the fuel level is within specs.

A specific dry measured float height is not the objective

The objective is correct fuel level when the carbs are being supplied with fuel.
This is referred to as the "service" fuel level.

Good Fortune!

I am using a PWK35 flat slide single carb. Unfortunately I cannot measure the float height with a clear tube because I do not have the necessary adapter.

it is possible to use a different adapter of some sort, I had to pick up my buddy's car when he went to court and it had the breathalyzer so I kept the mouth attachment and used it on mine. look around there are a wide variety of different things that can be used in the place of the standard tool.

treitz wrote:

Patton wrote: If not already done, would perform the clear tube test on each carb to assure that the fuel level is within specs.

A specific dry measured float height is not the objective

The objective is correct fuel level when the carbs are being supplied with fuel.
This is referred to as the "service" fuel level.

Good Fortune!

I am using a PWK35 flat slide single carb. Unfortunately I cannot measure the float height with a clear tube because I do not have the necessary adapter.

The special tool "adapter" isn't necessary.

Just use the bottom plug screw hole, same as clear tube testing smoothbores with the similar bottom plug.



Fashion a rubber plug/grommet arrangement whereby gasoline feeds into the clear tube through the bottom hole without excessive leakage.

A short section of oil line hose or a rubber grommet -- I use a cone shaped rubber grommet with a hole through it --with the clear tube snugly fitted inside.

Absent the actual true fuel level being within specs, further carb tuning efforts are futile.

Good Fortune!

even with jetting harley exhaust is not good. think 1200 cc x2 vs 45 cubic inch x2