All 2st About the Mikuni/Keihin swap:

It came with the blue needle already in place and then I switched out the 175 to a 180. Those are all the changes I had made besides putting the clip to the #4 position. I didn't touch anything else because nothing else came with the little bag of needles, etc.

well, i guess i'm on the bandwagon too. i'm not all that hard to please, so the mikuni was running fine, but it's a bit finicky, and by the time you get it to where it will start and run decently in the morning, then it gets to be painful to restart (hot engine) later in the day, and the stock needle feels rich in clip#2 as the weather warms, but clip#1 is unacceptably lean and low on power at small throttle openings. so rather than spend any time or money screwing with it, and with the idaho city isde qualifier fast approaching, i decided to pull the trigger so i wouldn't have to worry about kicking 10 times to start the bike at a gas stop or check or if i stall.

carb showed up saturday when i got home from 85 miles of hard fast singletrack in idaho city, and installing it went fairly smooth. stock cable and the noodle from the mikuni carb in place of the straight ferrule on the keihin. i scratched my head for a bit on the noodle and finally figured i'd start with it screwed all the way in, then screw the cap on (which unscrews the noodle 1-2 turns) then tighten the jam nut on the noodle, and live happily. Not quite as convenient as the straight ferrule, cuz it seems i'll have to loosen the jamnut to unscrew the carb top, but it's still way easier than 2 tiny easy-to-strip screws on the mikuni or the newer keihins. only annoyance is that these older carbs do appear to require the floatbowl removed to change the pilot. sigh. i guess i can do that twice a year.

based on what i read, i started with 42p, red #2, 175 (09 wr300), and figured that might be rich. it is slightly rich but perfectly rideable, and better than anything i found with the mikuni. all my 40p's are busy (in my 200 and my kx250) so i guess i'll have to get another one, and also a 172 main for rising temps and altitudes as the summer goes on, but this setup should work great for this weekend's race. Oddly enough, it's almost the exact same jetting that worked for my 2002 300exc that had the exact same carb. btw, this is for 4000-5000', 50-80 degrees, normally very low humidity, but today is was not low (raining, in fact).

went for just a short ride today to test, and it starts easier, esp when warm, and carburetes cleaner at very small throttle openings, and seems to have a bit more snap. I can't comment on peak hp because i'm a pansy and too scared to go that fast, lol.

i'm starting to feel really really comfortable on this bike now. made a few minor clicks away from LT's stock settings on the suspension, and now the carb and motor response seems to be just right. All that's left is to learn to ride.

thanks to all the folks that have posted in this thread and shared their experiences. that made the whole thing pretty easy.

What pilot jet is in there?

See how much better life is with the Keihin.

Now, if Husky would just see the light and save further owners $250 by switching, too. I'm sure it would improve the ragazine reviews.

Just checked and saw that it has a 45 pilot jet. Do most bike shops carry the 48 pilot jet or is this a special order specifically for this type of carb?

You might find a dealer with one, but you'll probable have to order. Here's a link tha Wallybean provided the other day for Keihin parts.

CARB PARTS

You can try the 45 and see what you think, it's not going to hurt anything. You might might even like the 175 main also. Don't be afraid to experiment a little. You shouldn't burn a piston or anything if you stay in that range.

Is the exact model I am looking for a '48 pilot for a PWK Keihin carb'? I have the carb apart in the garage waiting to decide on what to do for the pilot but worried if it might not start again. I am going to also do what Norman said about the throttle cable so we'll see how it goes.

If my local dealer doesn't have the 48 pilot, then I will hopefully order it on the internet and try to get it here by the weekend. Anywhere you suggest with the link for the part?

the pilots and mains for the PWK are the same as the FCR....should be avalable just about everywhere.....

Heck, I didn't know that! I do now!

I'm in north NJ and I have a 48 in my box...... I run a 42 on mine though....the pilots are the same for the FCR 4st carb too.

I could not get mine started for 2 days and 3 re-installations until I turned the idle screw in about 10 turns!

Good luck!

Sounds great about the FCR carb being interchangeable with the PWK main and pilot jets. Hopefully turning the idle screw in like R_Little mentioned will do the trick! I will probably head over to one of the local shops and see what jets they have so I can stock up on a few now that jetting doesn't sound completely foreign anymore. This site is really such a great place to learn new stuff!

Just got off the phone with my local dealer (an hour away) and he said he has a 48 for the Keihin that is an inch + half. Besides taking the carb back off later tonight after work and bringing it to him sometime during the week, does anyone know off hand if that should fit?

Yes, you need a "21" series pilot.

Maybe you should hook up with R_little and have him give you a hand with the carb. Might be good to have someone to show you your way a around with one.

You should be able to find those jets anywhere. KTM, Honda, Yamaha, Suzi and Kawi 2 strokes all have used the PWK at one time or another. I get them from a local ma and pa shop for $3. Or from the 'big 4' dealer for $6.

They're a dime a dozen!

Will not start

I have R_Littles's problem, I can not get this thing to start. New 09 300 I've ridden it a couple of weekends, have taken the mikuni off about a 100 times and still couldn't get it right, it's close but not as perfect as the KDX I have. So I ordered the keihin. 175M 45PJ air screw out 2 turns idle screw turned in enough to raise the slide to match the mikuni,
have spark and fuel, didn't measure the float level but it looks close enough.

On the KDX if I raise the choke I can't touch the throttle or it will never start, I do that on this bike and kick a couple times and pull the plug and the plug is nearly dry. Twist the throttle and the plug is wet but no go.

I have kicked this thing so much my knee is swollen.

Next step is to put the mikuni back on, warm it up good then slap the keihin back on.

Any other ideas? I'd go to a bigger pilot but the kit didn't come with one and I had to order it.

I found the 48 pilot and also got a 178 main for later experiments. I will put everything back on the bike later this week and report back!

i'd be surprised if you needed a bigger pilot. i went to a leaner jetting all the way around on my 09 300 (42p, red #2, 175main) and it's borderline rich now. mine will start (barely) without the choke. Is it possible you are just way too rich?

i guess i would find a big hill you could bump start on and then see if it seems overly rich. mine fired up 2nd kick, but i had turned the idle screw in a few turns and put my own jetting in. stock (45p, blue#3) i think would be excessively rich for a 300.