24 PWK Carb - 911

[WISH1965]

I have 70cc that has beed ported, good cvt set up, a 20 MM Keihen carb, and a DRR 90 pipe and an overall nice dependable set up. I have some time before the next race to try some new things due to my son's fractured arm, but my inquiry for help or advice is this. I have put a 24mm D-slide carb on it to try & see if this could work, because several guys have told me they prefer the D-slide over the round slide. I have two of these carbs so i figured why not. Well after changing needle heights many times & main jetting many times, I am finally close to going back to the 20 mm & the set up I had. The carb tends to just bogg at half throttle & up. The plug doesn't give me a good reading due to it not running very well for any length of time so not sure if rich or lean. I have gotten close to good at mid to 3/4 full throttle then full throttle just boggs & stammers?? When I go leaner it seems to ultimately cut out at high rpms if i can even get it to high rpms. It will not rev up with a load on it? Any thoughts?????????????

Current carb setting is: 40 pilot jet, needle in position 1, very top notch, and a 90 main jet.

Any advice greatly appreciated. Much Thanks.

WW

I believe with the d slide it should be about 2nd from the bottom 38-42 pilot jet and a 125 - 135 now remember JMO. The air screw set at 1 and adjust from there if any is needed. If im wrong someone please help out. You are to lean on top being the needle position. JMO

[WISH1965]

I did have it at that setting at one point. Not sure what the jet was when i was at that clip position. I beleive the reason I started going up (lean) on the needle clip was because i didn't have much success around clip positon 3-4 either, if i recall. I will try your setting. Sounds like you think I'm lean? I kinda have that feeling it is? The air/fuel needle I haven't really messed with much since it was on a stock DRR 90 motor. Maybe i need to address it as well and see where it is set. Appreciate your opinion/suggestion. Thanks.

Yes you said it bogged at 1/2 throttle and up. Well pilot runs 0-1/4 throttle , Main jet runs 1/4-3/4 and needle runs 3/4 to wot. Which means wide open throttle. I believe this is your problem. And no problem I love to help any kid who is willing to ride. The smiles on a kids is PRICELESS. I love kids and love to see them HAPPY. Thats what make my day.

[mxdad423]

There is now way that anyone could say exactly what jetting you should be at, differant temps, humidity, ect ect. for example I have had my jetting dead on for 2 months, we went 100 miles north last weekend and the temp was only around 58 degrees, I went from a perfect light brown plug and a great running machine to a snow white plug and a machine that wouldn't get out of it's own way.
I will definatley say that a 90 main is way to lean, and a 40 pilot is way to lean, an approx area for your area should be around a 50 pilot, and start at around a 135 main, clip in the middle. Tune your air screw first:

Start the machine and bring it up to operating temp
run the air screw in until the engine starts to drop RPM's
then run the air screw back out to it's highest RPM
shut the machine off and count the number of turns out the air screw is
You target is 1 1/2 turns out, more than 2 out you want to go smaller on the pilot less than 1 out you want to go bigger on the pilot.

After you get the air screw and pilot set, then move to needle then to main.

Remember, alot of people think that you pilot only works your idle circut, this is not correct, although each has it's destinct jobs, they all work togeather throughout.

Hope this helps you out

Kevin Smitley

Yes you are correct but what im saying was JMO it was a better start for him than where he was thanks for helping MXDAD423.

[bulldogfallon]

If it is a knock 24mm flat slide I would start at:

40-42 Pilot
Needle in the middle (as a sts starting point)
115 to 120 Main


I would take a Keihen roundslide anyday of the week to be honest.

Too many parents put big carbs on their quads because "bigger is better"....really it's not depending on the rider and the type of riding.

I think your set up is on the borderline between a 20 and 24....


The above recomendation is for the Sunworld knock off PWK24 in FL.

[jread14]

I have found the Keihin PE 24 (round slide) to be the best setup for the 70's. They are super easy to tune and very predictable. I think Gary gave you a great starting point. I am running a stock 70 DRR that is piped with the PE 24. My jetting is a 40 pilot, 125 main, and needle is one up from center. Keep in mind that I am down here in TX in the heat and humidity.

[bulldogfallon]

Jason your Keihin jetting is right where we would set it.

Those PWK seem to run a little lighter on the main jet.

We run here in Indiana a 38 pilot and a 128 main with a Keihin Pe 28 and clip second from top.

[bulldogfallon]

The PE28s seem to like a small pilot...where the 24 likes a bigger pilot in our experiences

I like the pe 28 its been the best carb. We have two one on our air cooled and one on our water cooled. Nice and fast tunning.

[WISH1965]

Guys,

I appreciate the feedback. I'll start from scratch with air /fuel setting, then I'll set needle @ #3 clip position, try a bigger pilot first, then try different main jets. i have a good assortment of main jets, but just the 40 pilot. FYI, it is a PWK24mm. Try & mess with it this weekend a little & hopefully report back. Again, much thanks. Going bald pulling my hair out :mad:

WW