Jetting Help

I have tried a variety of jets and I am getting pretty close. But I'd like to see if you guys agree with my line of thinking.

Currently, it idles pretty well, and operates great at full throttle. Where I am having issues is at lower RPM's. I.E. Right off of idle, and at cruising speeds. Like 4th gear at 40 MPH etc. It is definitely rich based on my black plugs.

Initially this lead me to the pilot jet. I basically jetted it down until it wouldn't even start, then went one up. So I am at a 45 pilot. My main I haven't messed with much because it is running fine at full throttle. Main is a 148.

My needle clip is at the highest (leanest) setting. I called a local shop and they suggested that I go down a needle size.

Does this seam like the best place to start to you guys too?

I went through my carbs last year after buying it and riding it for a year. I had a slight hesitation off idle to getting on it a bit. My bike would pop through the carbs a little bit on warm up. I replaced the carb boots that someone had jetted to the massive air leaks around each one. I ended up also replacing the o rings on my adjustment screws. My pilot jet is at 47.5 and my clip is second from the top. I have pods and 4 into 1 pipe. I am just stating that I would double check for leaks again. I would also throw a sync tool to it. I went down 3 jet sizes after fixing the leak and checking valves and double cleaning the carbs. Good luck

Sorry, I should have clarified. I am running a single carb PWK 35 flat slide.

you need to see if your air filter is clean.

I agree check the filter. But I would possibly look at different needle as you stated in your post. Its work a shot. I just have a hard time believing that you cant adjust it out with the clip and pilot jet.

make sure the muffler isn't plugged

gdprather wrote: I agree check the filter. But I would possibly look at different needle as you stated in your post. Its work a shot. I just have a hard time believing that you cant adjust it out with the clip and pilot jet.

It is a little weird... but the needle is on the lowest (leanest) clip setting, and I tried the pilot jet one size smaller and couldn't even get it to start. I guess if the needle doesn't work, I can try the smaller pilot jet again. Maybe I was doing something else wrong.

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Good Fortune!

If I am reading this correctly you are running a single 35mm flatslide then you are in the experimental stage here. A 35mm carb is big enough for a 650 but not a 1000. You can get it to work with a lot of experimenting. I would say call Sudco or the carb manufacterer and ask their advice regarding a baseline setting for the carb. The way you are doing it is going to take a lot of time and money, you will end up just guessing at what do and without any hard and proven information it will take a LOT of experimenting..

baldy110 wrote: If I am reading this correctly you are running a single 35mm flatslide then you are in the experimental stage here. A 35mm carb is big enough for a 650 but not a 1000. You can get it to work with a lot of experimenting. I would say call Sudco or the carb manufacterer and ask their advice regarding a baseline setting for the carb. The way you are doing it is going to take a lot of time and money, you will end up just guessing at what do and without any hard and proven information it will take a LOT of experimenting..

Ya sorry... I am running it on a KZ400. I will add bike information to my profile.

I called SUDCO and Carb Parts Warehouse and neither of them could help me because they cannot identify my OEM needle. It reads N0LB which is a manufacturer parts number. Since they cannot identify it, they cannot suggest a leaner needle.

I would say that 35mm carb is too big for a stock 400cc engine. You are going to have a hell of a time dialing that one in especially without knowing what the baseline is on the carb. Not saying it can't be done but you will be doing a LOT of experimenting.
With a carb that big you will be chasing performance between idle, mid range and full throttle. Once the idle is good then it won't perform well on the other two circuits. You will then try and get the mid range dialed in only to giveup headway on the idle circuit. Then you will try to get the idle back and mess up the midrange circuit. See where I'm going with this. A carb that big on a small motor is VERY hard to get right. Good luck.

baldy110 wrote: I would say that 35mm carb is too big for a stock 400cc engine. You are going to have a hell of a time dialing that one in especially without knowing what the baseline is on the carb. Not saying it can't be done but you will be doing a LOT of experimenting.
With a carb that big you will be chasing performance between idle, mid range and full throttle. Once the idle is good then it won't perform well on the other two circuits. You will then try and get the mid range dialed in only to giveup headway on the idle circuit. Then you will try to get the idle back and mess up the midrange circuit. See where I'm going with this. A carb that big on a small motor is VERY hard to get right. Good luck.

Thanks for the input. I understand what you are saying. However there are other guys using this carb on the same bike.

I might try tweaking my jets a little bit more and if that doesn't work try a smaller carb. Tracking down a leaner needle is proving to be nearly impossible.