I have just set up my old Keihin PWK 28 on my new Sherco 04. The best results were achieved with this settings: 45 low, 125 high, slide 3.5, air screw 0.75 to 1.25 turns... BUT I have a problem with the needle: with the clip in the middle position, the thing goes lean when chopped the throttle after a small opening. On the second position (from the bottom), the thing goes well but has blubbing (too rich) when throttle is open with load.

I deduced I need other kind of needle. Actually is a JHN. Anyone in there has information about JJH needle (same taper than JHN, same lenght, but seems to be 0.05 mm narrow on the cilindrical section, and that could be what I need).

I have experience with Dell'Orto but PWK is relatively unknown to me. Wayne, could you check the needle fitted on your Keihin? Any suggestion will be welcome.

Cheers, JM.

Edited March 31, 200422 yr by Marlintec

More than fifty views, none answer? C'mon guys! Is this so hard for you? I'm progressing by myself, found some charts of PWK needles and feel that it is almost done, but I would know your opinion, or guess, at least.

Cheers, JM.

I am having a hard time replying lately, I tried earlier in the week and could not get through.

Anyway, I know Wayne will answer your question, but he is in the middle of a field at the moment at TTC prepping Team Sherco Bikes for the National and repairing, tuning and adjusting bikes of all makes and models.

I would like to offer some insight, but have no background nor experience with those Carbs.

Many thanks, Alan. This afternoon I've tested the a JHN needle modified in the cilindrical section (I sanded 0.05 mm in a lathe) and it cured the pinging I described before. The bike runs very clean, more than with the original Dell'Orto, but i feel that more can be made.

I'm waiting to hearing from Wayne, many thanks again.

JM.

I`ve run the PWK for four years and have been really pleased with the extra low down tunability and the added top end power.I have ended up with a 38 pilot 110 main and the JJH needle . These have been used on 200`s - 290`s. Make sure you check the float level , setting is 19 mm. Definately a nicer carb than the Dellorto, especially on hot days, seems to hold its tune much better.

Good Luck

ShercoH

Not sure where Wayne is, but I happened to ask the jetting question after riding his bike last week at the nationals. I believe he told me 45/120 but he will need to confirm that as my memory is good yet short. The different needle may be just the trick to setting it right but as far as I know he has not changed his, but then I do not know what it comes with for sure!

MC

Hi all,

Many thanks for your answers. As I thougt, my problem was the needle. I got the carb with a JHN needle from stock and I didn't notice it until followed the carburation ritual without success. I tested the 50 pilot jet but it was too rich for my riding style. Finally, I got the pwk chart (attached copy) and noticed that JHN needle was 0.05 mm thicker than JJH. Finally I sand-lathed the JHN to remove those 0.05 mm. Now the bike runs well (no pinging at all) with unleaded pump gas (98 octane) and Castrol R2 at 80:1.

Cheers, JM.

Marlin what did you use for the carb/airbox rubber as the stock one is far to small,as I am just trying to get mine set up on my 2.9 sherco and where can you buy the JJH needles from as i have the JHN.

Thanks G.RASP

Hi, G. The simplest way I found was to use a car-radiator hose, 45 mm diameter, 45 mm length, and remove the thin plastic bash that goes round the original rubber.

Keihin carb will fit (50 mm diameter) and the air filter also (around 45 mm) in the new hose. Without the plastic, it's very easy to fit the airbox.

About the needle, I had to machine my JNH because I didn't found the JJH in near dealers. You could do the same, if you are or know an effiecient machinist. Just remove 0.05 mm from the cilindrical section.

Cheers,

JM.

where can you buy the JJH needles from as i have the JHN.

Thanks G.RASP

Try Allens Performance, nr Nottingham. They keep a good range of PWK needles and Jets 01949 836733

Thanks fella's will phone Alans performance when I get in from work tomorrow .

Thanks G.RASP

Howard, what was the setup for the Keihin on the 3.2, tried one for the past few day's and took it off.

Jetted at main 122, pilot 40 jjh needle.

Made the bike too soft and riding my practice section when wanting the quick hit from the bottom, had me ....ing mi sen up a double step, hits a flat spot just when you need it.

Put the Dellorto back on and she is twice the bike

Maybe Marlintec cann tell us where to find the properly set VHST for the Sherco! And the specs for it!

Ishy,

Didn`t spend a lot of time with the carb , was mainly chasing the querky starting . Ended up with a 110 45 and JJJ, Back on a 2T now

Found bike would not rev out cleanly with any bigger main, but needed to be rich down low to retain the punch. I think Paxau is doing a KeiHin for the 4T , would be worth asking what he is running.

Cheers,

ShercoH

Cheers for that Howard, think I'll stick with the Dellorto then.

Bike runs well with it on.