- This topic has 16 replies, 4 voices, and was last updated 11 years, 4 months ago by Joeb1983.
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April 23, 2015 at 7:19 pm #46736Joeb1983Participant
Just double checked. It actually has a #180 main and a #50 pilot…
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April 24, 2015 at 9:19 am #46767bo rougeouParticipant
First you need to look at the literature available on how a PWM works and the relationships of the needle and jets over RPM.
And be careful,use only Kehin jets so that the taper fits the needle.
I am no carb expert, but knowing how it should work will point you in the right direction
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April 24, 2015 at 11:09 pm #46813Joeb1983Participant
Yeah, if been reading all about it the past couple days.
Did a compression test and it was good.
Dropped the jets down to Kehin OEM specs. 160 main and a 60 pilot.
This things top end now is a beast and pulls the front wheels off the ground!
Off idle it’s a dog though… Stuttering and bogging. Need to mess with the Air adjustment screw and if that’s not the case start looking into the pilot more.
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April 25, 2015 at 8:12 am #46832Greg WrightParticipant
A check of the needle and needle position may be in order.
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April 25, 2015 at 10:02 am #46846Matt DixonParticipant
Sounds fat on the pilot.
We have a track that the AA gets over 7000ft. We dont usually get down to a 160, but close, but our pilot is much lower then yours.
But that is with a 99 CR125.Good Luck
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April 25, 2015 at 10:03 am #46847Joeb1983Participant
The clip on the needle was in the lowest/richest slot out of the 5.
It’s now in the 3rd/middle and I will just go from there.
I’m not sure why it was setup to run so dang rich…
Maybe it was a carb off something else and he just threw it on to sell it… Who knows?
Learning a lot though! So that’s a plus.
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April 25, 2015 at 11:51 am #46859Joeb1983Participant
I’m stationed in Oklahoma and our field elevation is roughly 1,200 ft.
Just throwing that out there if that helps. Thanks for the replies!
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April 26, 2015 at 9:25 am #46926Joeb1983Participant
From all I gathered from the past few days of reading kart & bike forums, articles and sites for both the yz125 and cr125; is I should be in this ballpark:
Main: 170 – 180
Pilot: 40 – 45
Clip: 2nd or 3rd slot
Air screw: 1-1/2 to 2 turns out.Like Matt said, fat on the pilot with the 60.
I’m throwing in a 170 and 45, 3rd clip, 1-1/2 turns out and see how that goes.
Like I said, the 160 and 60 was just a starting point seeing how that’s what the Keihin PWK 72 came with out the box.
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April 26, 2015 at 9:58 am #46931Matt DixonParticipant
Fatter pilot to start, those are mighty lean.
If it boggs off corner lean it out, if it hesitates then fatten the pilot. -
April 26, 2015 at 10:35 am #46936Joeb1983Participant
45 is lean for the pilot?. Most have been 42’s and 45’s I’ve came across for 125’s running Keihins (38 & 39mm)
The richest I’ve seen the main was 185, most were 170 – 180.
It’s apperant I’m confused… haha!
The 60 in it now I know is too rich. Even with the 50 it had in it before seemed a little rich as well.
It doesn’t like to idle and the idle screw seems to do nothing.
It bogs out of a corner for sure. Falls flat on its face… However, up top in the band it rips like I said.
I sent JD jetting an email as well, and I also know every kart/Bike setup is different.
Just trying to get it running right.
It’s been one thing after another and this is the LAST step. Everything else is paractically brand new…
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April 26, 2015 at 11:33 am #46940Matt DixonParticipant
Remember the 2 jets work together at WOT.
If the 2 motors should be jetted close then try 168/55/dgj2
We ran that just fine with the AA of 2000ft
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April 26, 2015 at 6:15 pm #46972bo rougeouParticipant
What Matt said. Be sure the pilot jet hasn’t picked up any trash.
That will make it behave like you described
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April 26, 2015 at 6:39 pm #46973Joeb1983Participant
The jets in it now are brand new (60 & 160) and I cleaned the carb.
I’m about ready to just order a OEM carb seeing how I know nothing about the history of this one.
Is the PWK 72 39mm to big for a 125? Also, are karts jetted differently than bikes?
Sorry for being a PITA. Just trying to figure this all out… Kinda frustrating. Lol!
All I know is it has a big carb on it, it doesn’t want to idle, the idle screw does nothing, it bogs hard when you first get on it, and it’s a rocket ship up top in the band.
I can bang gears all day long tbat way and it pulls hard. Just that horrible bogging down low when your not ripping it.
101 octane @ 32:1
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April 26, 2015 at 6:55 pm #46974Matt DixonParticipant
We run a 38mm in Stock Moto so 39 will be fine, save your money.
I have told you what you need to do to get it to run, we ran pilots in the 40’s when we ran a restricted Jr125.
It should not idle, the motor fuel requirements are much different then a bike.
Jets are cheap, put them in and you will be close.
New jets get clogged just as old ones do, run a filter.
Trust me go run it and report back, I gave you a fat set up but will “rip” at all rpms.
edit: 32:1 is what we always run
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April 26, 2015 at 7:12 pm #46975Joeb1983Participant
I really do appreciate it. I’ll head to the shop and grab the jets you recommended or order them if they don’t and a few other close in that range.
Thanks again. I’ll let you know how she runs. I’ll run through the carb again as well.
I should stay with the 3rd clip setting right?
I installed a new pump, lines and filter as well last week.
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April 30, 2015 at 6:24 pm #47314Joeb1983Participant
Update: ordered a JD kit. ended up installing a 55 pilot, 175 main, blue needle with the clip in the 3rd notch. Air screw 1-1/2 out.
(Kit didn’t have a 168 main, but came with a 162,170, 175 & 180)
17O was a little lean up top my buddy said according to the plug and 180 was a little rich.
She idles now and the idle screw actually works!
Low end cleared up nicely. No more bogging/hesitation. It’s now acting like a typical light switch 2-stroke. Lol!
Plugs is a light tan color after a WOT pull.
Thanks again for all the help guys!
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