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

I am running a 30 pilot with a 5.5 slide but am running the JD Jetting kit also. Be careful running the gay needle above # 4. If you ever are in a sand wash about 1/3 to 1/2 throttle BAD thing happen FAST. I got it to run on the GAY needle in #5 but the plug was still to clean for my taste.

A 5 slide will make your bike leaner compared to a 4 slide from 1/8 -1/2 throttle. Just like going up in needle base diameter. I don't like the "gay" needle. I used a 6DEY15-74 when i had the Mikuni.Much better. At around 20C i used a 40 pilot and 450 main. Then i got tired of the sensitivity of the Mikuni and bought a PWK Airstriker. better to jet and over 3hp more at low revs.

Mikuni tmx 38

Main 180
pilot 27,5
airscrew 1,5 turns out
Needle 6dj-?

Bike runs good, will try a bigger main and see what happens.

Hi guys. Quick question about setting the float height on a 2008 WR250. Having noticed while out on a ride that there was fuel coming out from the overflow pipe I thought I would measure the float height. It is currently sitting at 15mm (measuring while carb is at a 45 angle). I've read it should be between 18 - 22mm but what I can't find anywhere is how to raise the float level on the mikuni tmx 38. Can anyone advise or point me to a 'how to thread' as I'm sure it's been asked before so thanks for being patient.

many thanks in advance


Myles

++++ update - typically just found the answer!! Only one thing left, is 18-22mm the right height? ++++

wre125 any budy no what size jets come in the derestriction kit???

hey guys could use a bit of help, bike is a 2006 cr 125, completely stock. Plug is a perfect chocolate brown but I want to make sure the jetting is perfect especially since I just moved. Living in central texas now, what settings should I be at, recommendations?

Hi all,
Recently bought a 2014 cr125, and could use some help jetting. Can someone tell me if the below makes sense?

1) carb over flows easily - adjust float to barely touch pin

2) won't idle and adjusting air screw makes no change - go smaller on pilot jet

3) Bog when I whack the throttle, probably around 1/3 to full open on the throttle - ?? Not sure here??

4) bike is rich, visually on the silencer and speckled rear fender.


Bike is stock, running 40:1 with 93.

Any help would be appreciated. Thanks in advance.

First thing adjust float, should run a lot better then!

Knowing your location would help.

At a few hundred meters above sea level, I and another club member have found 30 pilot, 1 clip richer on the needle, and 460 main to work very well in summer. If it's cold where you are, that's maybe why it's bogging.

Thanks. Should have mentioned my location, Maryland, US - basically sea level, 60F.

Managed a little time to fiddle with the carb this afternoon. I adjusted the float, I think, at least to the point that it doesn't overflow taking it off/putting it on the stand. I swapped from a 45 to 35 pilot, smallest that came with the bike/144 kit. Also, I changed to the other needle that came with kit, really only because the one that was in from the factory had a small nick at the end. Put it all together and it fired first kick, with no choke which seemed odd. Also odd, but good, it idled. After warm up and a blast around the neighborhood it would no longer idle. But I also didn't adjust the air screw so that hopefully will have some affect.

My guess is that its still rich since it didn't need choke - so I am thinking to go a notch leaner on the needle, suggestions??

Also, I believe the bog is resolved. I did some slow roll on the throttle to see when it happens, but nothing, she just kept getting it

One more piece, which I can live with once the idle gets squared a way, during the test ride I spooled it up in either 3rd or 4th, then closed the throttle for maybe 2 seconds and then went WOT, and the result was zero power. Now it has been awhile since I raced dirt bikes, my last being a 05' RM 125, but I dont remember the power drop to be so noticeable. But just a little clutch and it was back. My only concern on this is being in the air and needing either lift the front or power out on the landing, and the engine not be there.

Thanks again for the info, and anything forthcoming.

Looking for ideas guys...
Just bought a 2011 WR 300. Beautiful bike with low hours (maybe 25) it has all the good stuff; hyd clutch, factory connection suspension, JD kehin carb...its SWEET !
Issue; runs well, but when come to a stop sounds very lean...scary ! "Ding, ding, ding" like you turned gas off.
It had a 170 main and 40 pilot when I got it.I went to 172 main and 45 pilot, and tried various needle positions
but the condition remains. Air screw has little to no effect on this. Float level looks good. Coolant full.
I have installed gaskets on both sides of the reed cage, as it acts like an air leak, no change. Wondered if thermostat
could stick, causing it to run hot, but is does not puke fluid and both side hoses are hot.
Location; GA 500 ft. Any Ideas of what to try next ? (Oh- carb is a PWM)
Thanks !

Did you check float level?

Yes float level good. Got some tips on this carb from James at JD jetting today. Will try the mods and post the results...

Ok, first let me say that James at JD jetting is awsome ! He took the time to listen to the issue and gave me the info
I needed to resolve it, with no profit to him. I have purchased his products in the past, and will continue to
support him in the future. So, the carb that was fitted was a PWM, not the PWK that works so well. To get a PWM to
work the slide and the needle schroud need modification. 10 minutes with a file has a notch in the bottom of the slide
and a cutout filed into the needle schroud. This increases the "signal" at low/idle throttle openings and solves the problem
inherent with this carb. The pictures show the modified slide installed, and the notch filed in the needle schroud.
With these mods and a blue JD needle( whitch I had in stock) @ 2nd notch, 172 main, 45 pilot - this bike rips
and has good low speed manners too!! Pumped for second ride on it this weekend , will post pics of bike..

Erock, it would be VERY useful if you could tell us what was in the carb right now. For example, saying you switched to "the other needle" is really not helpful, unless we know what the needle is (and what you switched it from). There should be a part number (small) stamped into the top of the needle, please post that. In addition, we need to know which clip the needle is on.

Set the float to the RIGHT level, not just one that stops it from leaking on the stand. Float height is important! It's possible you adjusted it too far, for example. Not saying you did, just that it's worth checking.

We need some of the information I posted above, first. Also, you need to do some messing around with the air screw before we can really give any recommendations, and we need to know where the air screw is set. You could have the right setup and just need a little air screw tweaking, or you could need to change the needle, clip, pilot, and air screw, but it's impossible to say with how little info you've provided.

35 pilot jet sounds about right. I would expect a 45 to be too rich.

It absolutely, definitely should not do this. If you shut the throttle and then open it back up, the bike should rip. I am on and off the throttle (on my 300, but same difference) in the woods all the time, and if I didn't get power getting back on the gas coming out of a corner or whatever, it would be a really bad day. Something is definitely wrong!

right i have a 2002 wr 360, im in the uk its average 13 degrees celcius and the bike lives at 800+ feet.
i had a stock tm38 with 430 main 40 pilot and 1 1/3 turn out on air screw on top notch of needle.

now it foweld plugs so i have messed about with it and have a 370 main and 30 pilot, mid clip of needle, the air screw made no differance to engine rpm untill 5 turns out, i threw a 35 pilot in there and same deal. but would almost stall when fully closed.
The plug looks a lot healthyer and the bike idles fine and rides better than the bogging dog it was before.

am i close with pilot at 35 or shall i stick 40 back in it as the foweld plugs usually happend on idling.
oh i lowered the float height from 20mm to 17mm that wouldnt affect the air screw would it?

thank you in advance and if i cant sort it i may just get a lectron but not too keen to go back to square one with a new carb.
regards jack

just bought lectron cheers for the help!

The metering rod should be near perfect for the low to mid when the Lectron is delivered. I would leave everything as is and go ride. If it spooges like crazy it's more than likely the power jet is to rich. I have my powerjet set at about one turn from closed on my threehundred and it perfect. Sorry I couldn't help with the other carb problems. The Lectron is just to easy to tune.Cheers.

no worries ive almost got the mikuni dield in i just cant be bothered with the fine tuning seeing as how tempremental engrish weather is.
i will be using it for an 18 hour trail using low throttle so want that to be spot on.

Well I just joined your club bought a 13' WR250 closeout tonight. I have Been riding a 00' CR250R Honda for a few years it has the same Mikuni that my new WR has so I have some experience with it. The one thing I don't see a lot of talk about is the nozzle jet that’s what I started with and once I got that right everything else fell into place and did not need to adjust again. No spodge and Jim beam colored plug. In the jetting data base there is not a column for the nozzle jet( Kehins don’t have one). I am in the calf high Desert about 3-4k elevation can anyone give some input or is the stock one work in most cases.

I just realized the dealer gave me a thumb dive with a service Manuel but it is for a 2011 any idea if it’s the same or have they made changes in the last two years