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

fitted a 144 cylinder to my 2002 cr125 here are the specs;
tmx 38 with custom plate on outlet(power now type)
pilot 15, main 370, slide 3 (modded) needle 60 in lowest position.my question is the bike idles just running on the pilot circuit i.e no lift on the slide at all is this correct tried 25 pilot but needed to lift the slide to gain idle and would foul plugs on rocky down hills (clutch in, braking and blipping the throttle) or waiting for 4wd to pass.i will take it for another run with the needle in this position to see if the fouling issue is resolved.

when you say lowest setting i assume you have the clip at the top
Its strange as I put my clip at the top and it was too lean and had to wind air screw in to richen it for an improvement and i have a 27.5 pilot 380 main same carb
how much did you take off the slide? is it a 4 now?

yeah quite a bit probably equivalent to a 6 however on the last run bike ran great, real responsive if you ride rocks try my fork mod, my son couldn't believe how much quicker I was through the rough stuff.need to dedicate a day to test the jetting at wot to make sure everything is safe oh by the way 190 psi cold engine must be pulling quite a bit of vacuum for such small jets i will be change from atf to diesel engine oil in the clutch/gearbox.

So I bought a 2011 WR300 as an upgrade to my 2002 KX250 and love the new bike. Working with the Tmxx i have the number 5 slide gay needle and have had to put some big jets in to get it dialed. 50 pilot and a 440 main with clip in middle position. Bike runs super awesome first kick hot or cold at 1200-3500 feet with air screw 1.5 out. Has anyone else used the 5 slide in the 300? Can't imagine buying another carb. Have had the bike up to 7800 feet with the 430 main and 2 turns out on the air screw and ran perfect. Plug is still a very light tan on the chop so I may still go up to a 450 main. Jets sound big but the bike is working so well. I think its the 5 slide that was the key as temps and elevation have little effect on the performance. Just wondering if anyone else has had similar results. Just a note that my husky spanks all my friends bikes in the handling department. I know the frame has been around for a while and now I see why they haven't changed it much it works so good.

How do you know what is taken off between each size?

using a small round grinding stone in a bench drill grind into cutaway trying to keep angle same measuring height of cutaway #4 would be 1mm higher than #3 .

"W do you know what easchww". What does that mean? Is that a question?

When RB cut my slide and did the experimental low circuit mod's to my carb I thought it would be to lean.Turns out it's not, still spooged with a 32.5 pilot going back to a 30 and going to try a couple different Yamaha YZ 125 needles.I'll let you know how it works out.I still don't like the leanness of the stock needle between closed and about 1/4 throttle opening.

With the GAY needle in the middle and 27.5 pilot I'm still rich below 1/4 throttle but I'm reluctant to go leaner on the pilot because I think it would make my bike hard to start and might be too lean on long downhills with the throttle closed. If I ride hard it's ok as is but if I stay in the really tight stuff for too long it starts loading up. I'm saving my pennies to send off the shock, forks and carb all at once so I won't have too much down time.

The number five slide did make my 300 very lean on long downhills with the 45 pilot. Once I put in the 50 and went to the 440 the pinging with the throttle closed went away. Four hours on a new plug and it looks brand new. Not even oily and no carbon. Should have the 450 jet in by the weekend and I'm hoping for even more power as I started with a 420 then the 430. Next the 440 and with each increase the bike just kept getting better. Can barly hold on to it on the big hills now it screams so hard.

RB

Here is a little help.

I use the 04 RM 125 needle 6CHY 16- 61 with a 5 slide in my 250 along with the newer TMXX carb. Anyone with older TMX carb that wants to convert to the TMXX has to buy the newer intake boot so carb doesn't rub on the cases.

I use the divider plate in front but I do my own carbs. It is well worth the money to have RB do your slide/carb mods.

I also use the thickest base gasket and set my powervalve at the motocross setting. Using the thicker base gasket also enables you to move your kicker back a notch or two. Heck of a lot easier for dead engine starts. I think it is set @ 48mm instead of 52mm from top of cylinder.

Another big plus is to go in and match your powervalve shaft cover to the exhaust port/polish it. Then pipe match your stock pipe to the exhaust port.

Run a 40 pilot / 440 main when cooler then go about 37ish when warmer out on pilot.

I have done some of my own port work but non the less, even with out the port work, the bike is a rocket, with good manageable power.

The GAY needle is a fast then slow then fast needle

The CHY needle is just plain fast needle with no hiccups.

The TMXX carb that Husky uses has a terrible lower circuit in it (both the 125/250) RB can fix that without trying to find a different rare TMXX carb.

With the divider installed up front, it still pulls like a PWK 36 but still have your top end.

Also, have them open her up to 39mm.

Took me couple years to get here but bike is awesome!

I had my Mikuni working well, but I also think the stock needle is too lean in the 0-1/4 range. I think the similar YZ needle with the next step richer on the starting diameter would be better. I was going to try that next, but I recently fitted up a 36mm PWK from a KTM300, so my TMXX testing has stopped. If you try that needle, let us know how it works.

Has anyone tried using the richer stock husky needle - 59 ? My 144 with TMX 380 main 27.5 pilot looked to be rich in the middle at needle setting 2 so tried 1 and it was too lean at the bottom . Bike still feels a bit flat throughout . If I was in the US I would get carb mod done but expensive to ship back and forth - may just go back to PWK
How does the 36 Keihin carb go from the KTM - I could try that as I have one on my other bike - no loss in top end?

I was looking in the 2009 YZ 125 service manual at a needle cutaway picture and it looks like the next richer needle 6bfy43-73 will stay in the richer part of the taper before it goes leaner again.I'd like to try that needle and it's half clip richer counterpart to stay richer even longer. I red some where on here that the stock needle is lean to meet eurospec's.

Yep, that's the needle I would try next.

I just got it put on so I only have a couple rides on it for testing. So far I can't tell any difference on the top end. I can say it is much smoother and more consistent running and has a little more power on the bottom. I'm not sure how it fits up on the 150. It is a little shorter than the Mikuni so I added a 3/16" spacer between the reeds and the cylinder. I also had to get a different petcock on the 250 and make a couple minor mods to the carb body, but you shouldn't have to do that on the 150. Check with Vinduro - I think he may have one on his 150.

Thanks for sharing this info.I was also considering a Suzuki needle but could'nt nail down an exact Suzuki part number for the needle everybody uses on the wr and cr 125's. 16-61 is just the begining part of the number when I was looking at the parts online.Could you get an exact part number please.

http://www.hillsboromotorcycles.com...y=Motorcycles&make=SUZUKI&year=2001&fveh=1990
Here's one of the places I looked, lots of chy16-61........here.

454X,

For sum reason, Suzuki took those part numbers off. You have to call them. But you need the 6CHY-16-61 needle.
It is one step leaner than the original one I found for the 125's. I have tried all and that's the best one in middle clip position. A lot of your issues are in that carb. The circuit was designed to come on more after 1/4 throttle. That's why it needs change for low circuit. Plus, with front divider your going to pull more air/fuel thru the first 1/2 of carb under the slide and get a boost of low end.

Next time you pull your cyl. Look at inside your cylinder at how rough it is in all the passages. If you go in and clean all those up smooth, match your powervalve shaft cover to the exhaust port, then hold it up against your pipe. There is a lot of stuff not making the exhaust gases exit thru pipe very good. Also, by using the thickest base gasket, you pick up some more mid and upper power, thus moving your port timing a little.
So by doing all the carb stuff and some cylinder work with pipe matching, you should be happy.

Another thing:

I took several of Walts inner powervalve springs (Out of his 125/144 kit) and stuck them inside my stock 250 powervalve spring. Thinking it would build bottom end by delaying the powervalve. Actually, it hurt my throttle response and top end. If anyone wants a project? I would send Walt a stock 250 powervalve spring and see if he can go to his supplier, get a couple of lighter springs on compression, but same lengths, it may be worth a shot. There might be some benefits to having the powervalve open lil faster? I am doing 5 vintage bikes till next spring and don't really have the time to test the theory.