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after struggling to get my jetting right on my kdx220 1998 model i have come up with a new theory and would like to ask peoples advice. my kdx runs super rich at idle and i have double and triple checked everything,right now i am at a 32 pilot jet and it easily needs a 28 pilot jet. my theory goes like this,the emulsion tube on my pwk was worn out so i got another machined up,first few attempts was too small internal diameter and the needle was lean to the point of stalling at 1/8th throttle but needed a 45 pilot jet, as i got the emulsion tube size right it now needed a 32 pilot jet or smaller just to idle. the reed cage was ground out so i needed to make up gaskets to create a new sealing surface,could the turbulence created be sucking fuel from the emulsion tube rather than the pilot jet orifice thus creating a super rich condition. need to know my theory is right before i spend dollars tracking down new parts,in thailand where i am parts are non existent and import tax is huge

photos are posted on thumpertalk as i still haven't learnt how to post photos on here and my appologies for having to post the link

https://thumpertalk.com/forums/topic/12 ... my-theory/

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here is the butchered reed cage

KDXGarage wrote: 12:38 am Feb 10 2019 Click on full editor.
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thankyou for showing me,i am technologically hopeless

You're welcome.

Do you think the huge hole has something to do with the jetting being off?

thats what i am trying to determine but i have no way of testing

I don't think the hole would be the problem. Also, why are you running two gaskets? You only need the outer larger one. Are you sure on your float height? Don't run the factory float height as it can contribute to a rich idle condition. Have you done a leak down test?

SS109 wrote: 08:07 pm Feb 10 2019 I don't think the hole would be the problem. Also, why are you running two gaskets? You only need the outer larger one. Are you sure on your float height? Don't run the factory float height as it can contribute to a rich idle condition. Have you done a leak down test?

the smaller gasket is to allow the sealing hole in the airboot something to sit against, the surface of the plastic cage was damaged so i had to shave it down a milimetre or so,the small gasket brings it back to flush. float height is set using the clear tube method level with the fuel bowl mating surface and the needle and seat are vacuum tested to check sealing perfectly. engine is completely rebuilt with new crank seals, vaccum test was hard to do given i couldn't replace the packing seal on the power valve shaft but i did do a leak down test to make sure no leaks around the carb boot. 99 percent sure crank seals aren't the issue as the first 10 seconds that the bike is started after being cold it runs perfect at idle then runs worse as the engine heats up

correction on the plastic cage being shaved down,i should have said there were bits and pieces of what looked like a clear expoxy on the surface which i sanded/shaved down

How is your needle valve seat looking?

TRUAX wrote: 02:37 pm Feb 11 2019 How is your needle valve seat looking?

as stated the needle valve and seat were vacuum tested

If a leakdown test was good and you have no airleaks between the carb and the motor, then your problem is back at the carb. Given that you made your own emulsion tube which is a non replaceable part on the PWK its likely that it is slightly oversized, it doesn't take much you're working in the thousandths of an inch territory. You've spent so much time working around the fact that your carb was shot and needed replacement. I would suspect that above everything else at this point. Perhaps you can find a locally sourced carb from a goood running bike, doesn't need to be a PWK or even a Keihin as long as its functional.

bufftester wrote: 10:36 am Feb 12 2019 If a leakdown test was good and you have no airleaks between the carb and the motor, then your problem is back at the carb. Given that you made your own emulsion tube which is a non replaceable part on the PWK its likely that it is slightly oversized, it doesn't take much you're working in the thousandths of an inch territory. You've spent so much time working around the fact that your carb was shot and needed replacement. I would suspect that above everything else at this point. Perhaps you can find a locally sourced carb from a goood running bike, doesn't need to be a PWK or even a Keihin as long as its functional.

I also considered that but it's not the case, firstly I also have a spare pwk 33 which still needs to use a 32 pilot jet, secondly the emulsion tube is a tad undersize not oversize, I know this because if I put a CGL needle in it, it has the horrible lean bog at 1/4 throttle

So here is what I learnt today. Yesterday I used a die grinder to try smooth out the curves on the plastic cage, I used to port heads when I was younger so not so difficult, riding the bike now and it runs slightly worse at idle and lost 30 percent of power at 1/2 to full throttle. That plastic cage design is everything. Feeling p...ssed off

If you're making the hole bigger then you are changing the incoming charge velocity which will definitely impact the operation of the motor. If you can find someone with an unaltered cage that is off the bike they could measure the stock diameter of the hole and you could easily build a restrictor plate to try and compensate.