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1994 kdx200 just slapped in a 155 and it runs like crap, it ran OK but no top end with the 122 but now on WOT it just splurges.... any ideas?

122 is too damn lean! Get that thing outta there ASAP! What are you running for a pilot jet?

it has a 45 pilot jet and yeah, thats exactly what i thought, i have 155, 160 and 162 main jets to hand, have tried them all and it dies on wide open throttle with and without the airbox lid, went to the shop they cant get the jets til monday (ordered 130 140 150) but without the lid the 122 goes like stink! needless to say i am very very confused atm!

even though the carb looks exactly like the one in the manual it is stamped PE on the side, is this correct?

155 should be about perfect! I wouldn't go any lower until you figure out what is wrong here.

What needle and what does it look like? What is your air screw set at?

155 doesnt work WOT atall... air screw is 2 turns, aint looked at the needle, looks like its 2nd position from the bottom tho

Well the point is... IT SHOULD!

Something is wonky and trying to adjust a carb that is out of wack with a wrong main jet is pissin' in the wind.

you don't think i know IT SHOULD?

im just wondering if there were any discrepancies which would cause this to happen!! for example my mate has a DT125 which for 1 year only had the exact some model carb but with a "/1" at the end which suddenly meant it required to be jet about 50 sizes over that of standard!

is there something odd with a certain model? is my carb that says PE on the side something different?

if you look at this

http://www.allensperformance.co.uk/prod ... carbs.html

PE and PWK are 2 different types! is your carb flat slide or round slide?

That should be a PWK... theres your problem. I can't help you with a PE and doubt anyone else will be able too.

Start saving your pennies

i just bought a 36mm PWK off ebay for £40 ($62.13)


gotta love buying bikes off ebay, WHY IN HELL WOULD SOMEONE DOWNGRADE A CARB!?!?!?

what are the actual mods he does on those carbs anyway?

moto_psycho wrote:what are the actual mods he does on those carbs anyway?

It says right on his website what he does.

SS109 wrote:

moto_psycho wrote:what are the actual mods he does on those carbs anyway?

It says right on his website what he does.

Boring carb to 36 mm (gives you a better top end)
Installing divider plate (gives that low end response, like a smaller carb)
Modify slide (do not forget to send your slide with your carb)
Install new needle (gives the carb that personality)
Change jets (if necessary)
Modify jet block (helps with the over all performance)
Modify low speed circuitry This part of the modification along with the other mods really brings the air mixture screw into play. With only very small adjustments, you can keep your bike running at its peak as you change altitude or with weather changes during your ride.


wow, so informative. somehow i remain sceptical, unless specific details are given. i could scratch my name in the slide and call that modification :p

moto_psycho wrote:
wow, so informative. somehow i remain sceptical, unless specific details are given. i could scratch my name in the slide and call that modification :p

Before making that kind of comment, you should read the dozens of posts where riders report on the improvements.

I wouldn't expect RB to show pictures and detail out every little thing he does. Those are his 'trade secrets'.

Boring carb to 36 mm (gives you a better top end) - simple...
Installing divider plate (gives that low end response, like a smaller carb) - most people don't believe this works, but once again, simple and probably about 20p's worth of ally
Modify slide (do not forget to send your slide with your carb) - I would imagine adding a radius to the bottom of the slide to improve airflow?
Install new needle (gives the carb that personality) - crazy..
Change jets (if necessary) - more crazy
Modify jet block (helps with the over all performance) - shortenened to allow quicker fuel delivery?
Modify low speed circuitry This part of the modification along with the other mods really brings the air mixture screw into play. With only very small adjustments, you can keep your bike running at its peak as you change altitude or with weather changes during your ride. - sounds very much like its just been bored to a larger diameter


just what i'd imagine anyway... yes, im a big old pain in the

but yeah, before and after dyno figures would be nice :)

when my carb turns up ill get some mods done myself and get some pics up / tutorials

Whatever dude. Good luck with that.

My Dyno is the seat of my pants.

got an engineering shop the size of an olympic swimming pool at my disposal thanks!

but yeah, seat of pants works well enough but sadly there isn't an international standard for measuring the SOP-Dyno

I use my KDX for fun... not profit so it just isn't that important to me to tweak to the end all be all KDX. I know what works and at what price point. Riding isn't my only hobby so I will just pay Ron to do his magic and be done with it. It works and is very reasonably priced.

I could care less about international anything to tell you the truth.

moto_psycho wrote:got an engineering shop the size of an olympic swimming pool at my disposal thanks!

but yeah, seat of pants works well enough but sadly there isn't an international standard for measuring the SOP-Dyno

''The crow that has just been crying is now laughing''