All 2st Jetting Chat - Need Help? Post Your Questions Here

...sorry for the late reply. Maybe you get the info from somewhere else in between.

Suzuki number is 13383-36FQ0 for the 6CHY16-62 needle.

http://www.alpha-sports.com/suzuki_parts.htm?fpg=/smoto/2004 RM125/02.htm

jeanjean

I also found out that my 2009 wr250 likes running lean at low revs and throttle settings.
My Keihin PWK 38 AS settings at sea level and at around 0 degrees Celsius (32 degrees Fahrenheit) are PJ40, airscrew 1.25 turns out, DDM needle at #2 (second groove from above) 178 MJ and slide valve #8.
It runs without virtually any 'blubber' at all loads, speeds and throttle settings and does not bog when opeing the throttle too fast at low engine speeds. Changing the slide valve from #7 to #8 made a big difference in running at about 1/8 throttle in the tight single tracks in first or second gear. On #7 I could not get rid of the slightly rich running ('blubber'), even after installing a smaller pilot jet and a needle with a larger diameter of the cylindrical top part (in this case a DEN).
It took me quite a while to think about changing the slide - it is fairly expensive and almost anyone uses the stock #7 slide - but it was worth the time and money. Apparently, the slide cutaway dominates the mixture ratio just above the pilot jet's domain and just below the needle diameter's domain. Anyway, I like the crisp running at low engine speeds and the more or less linair power curve with the single taper needle.

I am an aging rider of mediocre talent riding in sandy and muddy corn stubble and slippery single tracks in the woods in the Netherlands.

Besides changing from Mikuni TMX to Keihin PWK I installed a 6 speed gearbox from a 1999 wr360. Huge improvement compared to the stock close ratio 5 speeder, low first for the tight stuff and a usable top gear on the road.

Enjoy 2017,
Berthil

Hi,
About a year ago i bought a 2012 WR 250 with only 200km on the meter... now it has 46 hours more.

Last weekend i scored the piston. We were enjoying some freeriding on a big local field, the bike was great as always...
I had to try its max speed becouse not had the chance to try it out before. A coupple of hard acclelerations from standstill to fifth and some time on fifth gear. Then i turned back and reached third and the bike died without any drama, sounds or resistance. No compression when i tried the kickstarter with my hand.

I tought i had burned a hole in my piston. We hauled the bike back to my frieds house and i removed the head. Suprised to see the cleanest piston and head in a stroker that i ever witnessed. The next day i brought the bike home and removed the cylinder, pistonrings had trapped themselfs in the heated piston.

I will try to uppload pictures later tomorrow.

Is this cause of lean jetting, the manual says to get a 430 main and a 40 pilot on 0deg cels. and at sealevel.

It was exactly 0 cels and im at 58m above sealevel, running a 420 main and a 42 pilot. Otherwise stock, the bike came with this jetting and a fmf gnarly.

And yes, im new to jetting a stroker...

Heres some pics for u experts!

Get a JD Jetting kit. The stock needle is just too lean.

Lean enough to cause a that?

I allso found a rip in my intake boot... ordered a new one.
Allso a wössner slug... and some jets.

What needle should i replace the original with? Any good options beside the jd kit?

If the intake boot you're referring too is the one between the carb and the engine, you've found your problem. If it's between the carb and airbox, you've just saved your new top end from wearing prematurely.

Was it pinging at all detonation traps the rings causing blow by, burning the oil from the cylinder wall and siezing piston.if your doing lots of high speed increase your oil ratio caster blend is best but clogs pvs.as oldscool said torn boot between carb and cylinder equals lean mixture as does jetting for regular riding then doing constant high revs/high speed esp in cooler climates with greater wind chill.always pays to do a leak down test after seizing and rebuilding.

The bike rips again.
It was the intake boot that caused it to run lean.
Got 6h of riding on the new piston.
Siliconed the boot against the reedvalve frame... its running as strong as before.

Thanks for the help.

Ok guys got a bit of a head scratcher for you, my 1999 wr 250 has had a carb change to a keihin pwk 38 A.S. ive finally given up on the old mikuni.
Jetting so far PJ 52 Needle Suzuki NEDH 3rd clip Air screw 1 3/4 out bottom to mid runs great and she idles well. The MJ so far is at 185 which seems to me being to big, and yet still shows lean on the plug. Im at 500 ft and temp today was 20 degrees C. The old mikuni mj was at 400. i know there that theirs no direct cross over between the jets. Im just wondering which way to go other keep buying bigger jets and bumping it up until she runs boggy. im also running premium unleaded fuel @ 50.1. The bike is fitted with a fmf gnarly, boyesen dual stage reeds, with a cylinder over bore at 67 mm. Any ideas or input welcome.

First figure what throttle position it's at when it's lean. Idle-1/8 = pilot 1/8-3/4 = needle 3/4-full = main. It helps to actually mark you grip and throttle housing with tape. Most of the time you are not on only the main jet circuit so it's best to adjust one circuit at a time. I prefer to keep going rich on one circuit until it gets lazy and then go back a step to crisp. This way you are in the place where it runs the best and is the safest setting to prevent a lean melt down. Keep in mind that there is overlap between circuits and also the air screw in in play from idle almost all the way through the needle circuit. One of the most common mistakes is to adjust the idle screw until the slide is raised past the point where the pilot jet is effective so the engine is basically idling on the needle and then adjusting the air screw out to compensate and get it to idle on the needle circuit. I've found that using a smaller pilot that requires an air screw adjustment between 1/2 and 3/4 turn out and then lowering the slide gets better results then raising the slide until you're idling in the overlap of the pilot and the needle. Hope this helps, good luck and be patient.

Thanks Doug it makes sense now, im just waiting on a hand full of brass to turn up in the post and ill go from there.

Hi all, just to update on whats going on with the bike its now near perfect and runs awesome. For those looking to replace there old Mikuni with keihin PWK air striker do it.
Here's what we ended up with a 55 pilot jet, Suzuki NEDH needle in the 3rd clip. Stock PWK slide with a 200 main jet and the air mixture screw at 1.5 turns out
This mod has made a massive difference in how everything comes together.

Where's the best place to buy bulk jets?

i would say maybe jets R us or sudco

I Have problems with jetting of the pwk on my 125.

Year & Bike Model = 2006 WR 125
Carb = Keihin PWK 38 AS
Pipe & Silencer = Husqy 125 CR pipe and Bud racing silencer
Other engine mods = VForce3, transfer ports' casting flaws cleaned
Premix ratio & fuel type = Castrol Power1 racing, 2.5% / 40:1 and 98 octane
Temperature = Around 15-20 Celsius / 65 F
Elevation = 114m/374ft.
Main jet =185
Pilot jet =38 (!!!)
Needle =NOZF from a ktm
Clip position = 3rd
Air screw setting = 2.5 turns
Slide = 7
Air filter is clean, topend should be in good condition
Fuel level= fuel starts dripping when the bike is leaned to about 45 degree angle.
Conclusions/Results = Bike idles, sounds ok, doesn't seem lean even with a pilot jet as small as 38! But if i let it idle it gets awfully loaded up. Blubbers and loads up also when riding on very small throttle opening (up to 1/4), if i don't clear it up, it will foul a plug. On around 1/2 throttle blubber is gone and bike seems to have poor power (lean?). Wide-open the bike starts to kind of stutter, bog (sometimes even pop loudly and throw a flame out of the exhaust).This missing started occuring after changing from vf2 to vf3. going from 180mj to 185 didn't help. I tried to retard ignition timing, helped only a little bit.
It has overall pretty poor performance now, poor low-end torque, poor top-end- and over-rev power. The bike should have a little more power.
I think i should get a steeper needle?
What could cause the missing/stutter? Is it just the reeds?(shouldn't be)
Fuel level high or low?
Any suggestions?

Is it me or is 38mm on a 125 way way to big a carb. ?!

Hello guys, just bought a pwk (non a/s) from a 2005 Ktm 125, I do believe it is a 39mm. I’m going to be putting it on a 06 wr 125, does anyone know what the jetting would be for this? Or even a base line setup.
Many thanks, andy

what is the slide cut? smaller cut increases speed of air across the needle jet
NOZF is one of the needle choices for my 380, it has WAY more air across the needle jet at 1/4 throttle