Idle and air/fuel not adjusting

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Idle and air/fuel not adjusting

Postby Mav » 08:42 pm Mar 21 2018

So when I screw the idle and/or air/fuel screws in or out (not matter how far) my idle doesn't change and I can't tell that anything is changing with the air-fuel screw.
This is my first 2 stroke bike, but I have no problem tuning and adjust all my 2 stroke equipment. I'm beginning to wonder if the screws are damaged and wont adjust. The bike runs fairly well but will not idle without dying unless I slightly blip the throttle every few seconds or hold the throttle just the slightest bit open.

Starts first kick and acts the same on 94 and 100LL (AVgas)
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Re: Idle and air/fuel not adjusting

Postby claybo » 08:51 pm Mar 21 2018

Sounds like it may be running rich. I had the same problem and it turned out to be the jet block gasket. If the carb has ever been dipped, the gasket may be damaged. You can order another one through jetsrus.com if so.
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Re: Idle and air/fuel not adjusting

Postby Jason » 08:58 pm Mar 21 2018

Have you tried a different sized pilot jet, like the next size smaller?
Thank you, Julien D for all your hard work!

PLEASE! Do not "dip" PWK Keihin carbs in Berryman's to clean them! It will damage the internal o-ring (jet block gasket).
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Re: Idle and air/fuel not adjusting

Postby Mav » 09:03 pm Mar 21 2018

I haven't gotten too deep into it yet. Just got her on Friday.
I'll try both those suggestions, its extremely clean inside, so it probably has been dipped.
I'm not sue if I'll rejet though because I'm going to do the RB carb and head soon.
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Re: Idle and air/fuel not adjusting

Postby Jason » 09:14 pm Mar 21 2018

Between now and then, can you not buy a pilot jet??
Thank you, Julien D for all your hard work!

PLEASE! Do not "dip" PWK Keihin carbs in Berryman's to clean them! It will damage the internal o-ring (jet block gasket).
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Re: Idle and air/fuel not adjusting

Postby Mav » 09:19 pm Mar 21 2018

Oops, yeah sorry Jason I can. Tired mind all I could think of with rejetting was having to buy a whole jet kit. I'll get a size up and down pilot and main jet as well as the jet block gasket.
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Re: Idle and air/fuel not adjusting

Postby Mav » 09:20 pm Mar 21 2018

Oh yeah. It is a PWK carb just to verify.
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Re: Idle and air/fuel not adjusting

Postby Jason » 09:46 pm Mar 21 2018

You might need it in the new Keihin carb.
Thank you, Julien D for all your hard work!

PLEASE! Do not "dip" PWK Keihin carbs in Berryman's to clean them! It will damage the internal o-ring (jet block gasket).
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Re: Idle and air/fuel not adjusting

Postby Jason » 09:48 pm Mar 21 2018

Also, if it is not running very smoothly, you might want to hold off on buying a new carb or other big money purchase.
Thank you, Julien D for all your hard work!

PLEASE! Do not "dip" PWK Keihin carbs in Berryman's to clean them! It will damage the internal o-ring (jet block gasket).
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Re: Idle and air/fuel not adjusting

Postby John_S » 10:08 pm Mar 21 2018

While you're in there check your float height. When mine is at 16mm it wouldn't idle and I kept going down on the pilot jet (all the way to 35) and it was still too rich. This was on a brand new carb. I set it to 18mm and have read that others run theirs at 18mm. That fixed it and I ended up with a 40 pilot jet with the air screw 1.5 turns out.
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Re: Idle and air/fuel not adjusting

Postby Mav » 11:45 am Mar 22 2018

Jason wrote:You might need it in the new Keihin carb.

What do you mean?
How do I know if it's the new Keihin? It says Keihin on it, but I thought PWK was just what everyone calls it.
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Re: Idle and air/fuel not adjusting

Postby Mav » 11:48 am Mar 22 2018

Jason wrote:Also, if it is not running very smoothly, you might want to hold off on buying a new carb or other big money purchase.

Will do thank you. Everything seems great other than that. Replaced front sprocket and chain, ordered fork seals, rebuilt petcock, and fixed the leaking float needle (it wouldn't stop fuel flow and the petcock didn't shut off fully)
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Re: Idle and air/fuel not adjusting

Postby Mav » 11:51 am Mar 22 2018

John_S wrote:While you're in there check your float height. When mine is at 16mm it wouldn't idle and I kept going down on the pilot jet (all the way to 35) and it was still too rich. This was on a brand new carb. I set it to 18mm and have read that others run theirs at 18mm. That fixed it and I ended up with a 40 pilot jet with the air screw 1.5 turns out.

Will do John, thank you. Is there a thread on how to check float height?
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Re: Idle and air/fuel not adjusting

Postby david » 12:40 pm Mar 22 2018

It's in the service manual, that should be your next purchase. You can usually get a nice used one on ebay for about $35
'81 KDX 175
'90 KDX 200
'07 Vulcan 2000 Classic LT (totaled 4/25/15)
'82 Honda GL500 (sold)
'96 ZXi 1100 JetSki
'98 STX 1100 JetSki
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Re: Idle and air/fuel not adjusting

Postby John_S » 01:19 pm Mar 22 2018

Yes for sure get an owners manual. I've referred to it so many times and have it nice and greasy now. In the meantime google "pwk float height" and watch that 3:03 video that pops up. That gives you procedure but he runs it parallel which on our carbs is about 16mm. 18mm is the distance from the carb body to the high point (or peak) of the float when its on the 45 degree angle like he's holding it. That channel "dirt and iron" has a lot of good videos.
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Re: Idle and air/fuel not adjusting

Postby Jason » 04:33 pm Mar 22 2018

Mav wrote:
Jason wrote:You might need it in the new Keihin carb.

What do you mean?
How do I know if it's the new Keihin? It says Keihin on it, but I thought PWK was just what everyone calls it.


Keihin PWK carb

Even if you buy it with the perfect jets, altitude, humidity and temperature changes will require slight adjustment from whatever it is set at.
Thank you, Julien D for all your hard work!

PLEASE! Do not "dip" PWK Keihin carbs in Berryman's to clean them! It will damage the internal o-ring (jet block gasket).
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Re: Idle and air/fuel not adjusting

Postby tmmyghst » 06:02 pm Mar 22 2018

Don't forget to check the reeds. (piece of mind)
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Re: Idle and air/fuel not adjusting

Postby Mav » 10:18 am Mar 23 2018

Thank you everyone for the help and advice, I ordered the parts and will order some reeds (even if I don't need them, they'll be in the KDX specific parts tool box)
I already have the owners and service manual, I'll check it (I keep mine in page sleeves in a three ring binder, as well as parts receipts, maintenance docs, ect.... I do that for all my vehicles and equipment, have a library in my garage.
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Re: Idle and air/fuel not adjusting

Postby Mav » 09:12 pm Mar 23 2018

so i pulled the jets and needle, the results are.
Main: 145
Pilot: 42
Needle: R1173L
The manual says that the 220 didn't come with a 145 Main, so i guess that is an adjustment made by a previous owner.
It also says that 42 Pilot only came in the 200.
Finally it also says that the 220 didn't come with a R1173L needle, the 200 did but its a R1173K.
So what jet do I try first, still one size either way? If it helps any, I'm only at about 350ft elevation.
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Re: Idle and air/fuel not adjusting

Postby John_S » 10:13 pm Mar 23 2018

42, 145, 1173L IS the stock jetting for a 220. Where in the manual are you reading that it didn't come with those jets?

The H series 200 came with 48, 160, 1173K stock
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