168 Main Jet? Why? And E-series Carb on H-series?

A reference for the PWK carbs...
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Joshmcmillan
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168 Main Jet? Why? And E-series Carb on H-series?

Post by Joshmcmillan »

Hey guys,

Just got a new KDX200, 97 model, road registered in very good nick.

I got it stock, put an FMF fatty and PowerCoreII silencer on it, going to drill some holes in the airbox lid (already has snorkel removed), reeds and I run 98 oct at 40:1.

Two questions. Stock jetting was 168 main and 42 pilot. WHY would anyone put a 168 main jet in it? I'm worried I might have some sort of different model that for some reason needed richer main jet, I was just going to throw a 152 in it, but a drop that big now seems drastic!

Secondly, I believe H-series have a stock carb that is 33mm? If this is the case, should I swap the stock 36mm PWK carb from my E-series (1994) onto it?

Any comments appreciated! Cheers :D Loving the KDX's!
07' CR450X (Main Bike)
07' KX125 (Completed basket case rebuild, for sale)
88' KDX200 (Not sure yet, runs but with rattly top end)
91' CBR250RR
Old Bikes: 97' KDX200, 00' RM125, 85' XR350, 94' KDX200, 02' CR80, 82' XT250, 98' CT200
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scheckaet
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Re: 168 Main Jet? Why? And E-series Carb on H-series?

Post by scheckaet »

follow the jetting how to (see sig) and you'll sort it out. Do NOT jump down from 168 to 152.
It is indeed very odd to have something this rich, how's the bike running?
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fuzzy
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Re: 168 Main Jet? Why? And E-series Carb on H-series?

Post by fuzzy »

They are both 35mm PWK's.

My first KDX had a 170MJ in it. I think it was done to tame power delivery as it was a dog, but still didn't foul plugs. I actually didn't know what a dog it was until I dove into jetting it, then was very surprised. 15+ years ago. :shock:
'91 KDX 200 Project $300 KDX
'95 KDX 200 Project $600 KDX
'94 WR 250 Always a project
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Joshmcmillan
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Re: 168 Main Jet? Why? And E-series Carb on H-series?

Post by Joshmcmillan »

I jetted my old 94 KDX200 and I think I have it perfect atm. It has 155 and 42. I think I have a 160 out of an old KX carb somewhere I might try that first and check it's not to lean.

It seemed to be running fine, but that being said, I put it's sluggishness down to the 14/45 gearing when I'm used to the 12/48 I put on my old KDX. It also seemed to begin to foul quickly while trying to warm it up, so I might check the idle screw as I think 42 PJ should be about right.

MY 94 KDX200 was a 'competition' model here in Australia, no compliance plate, speedo or anything, and a 36mm carb standard. Maybe I could just swap it right in jetting and all? :P

I think you might be right about it being done to control the power delivery, I don't think the past owner was at all comfortable with it even still, didn't like it doing wheelies, where my first thought is, why isn't it doing wheelies in 5th gear. lol.
07' CR450X (Main Bike)
07' KX125 (Completed basket case rebuild, for sale)
88' KDX200 (Not sure yet, runs but with rattly top end)
91' CBR250RR
Old Bikes: 97' KDX200, 00' RM125, 85' XR350, 94' KDX200, 02' CR80, 82' XT250, 98' CT200
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Re: 168 Main Jet? Why? And E-series Carb on H-series?

Post by fuzzy »

36 is same body as a 38 so I'd be surprised....Unless they made a completely different intake manifold and air box.
'91 KDX 200 Project $300 KDX
'95 KDX 200 Project $600 KDX
'94 WR 250 Always a project
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Joshmcmillan
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Re: 168 Main Jet? Why? And E-series Carb on H-series?

Post by Joshmcmillan »

Sounds like a 35mm might even be better for low down torque anyway?

I forget why I was sure my E-series had a 36mm, I'm pretty sure it said PWK36 on it, either that or I got mixed up somehow. I remember talking to another guy here in Australia with the competition model as well.

I've got a 160, 155 and 152 to try on my new H-series KDX. I'll go down progressively, I'm assuming 155 will be about right, it would just be a huge drop from 168 in one go.
07' CR450X (Main Bike)
07' KX125 (Completed basket case rebuild, for sale)
88' KDX200 (Not sure yet, runs but with rattly top end)
91' CBR250RR
Old Bikes: 97' KDX200, 00' RM125, 85' XR350, 94' KDX200, 02' CR80, 82' XT250, 98' CT200
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