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

I feel the same way sometimes,my wr150 will be spot on one day and too lean or rich the next depending on which way the wind blows,I may put a keihin on it soon. Hope you get it sorted, I am sure that some-one else will chime in with some advice,good people here..

Just Have RB do his low ciruit mods and plate to your Mikuni , problems solved. Then Mikuni works better than the Keihin after the mods and it is alot cheaper than a Keihin swap

my jetting is now perfect, tried lots of different combos but all is well now, i bought back my old gg ec200 from my mate who is not into tinkering and will be going back to 4t, my 9 year old son wants his big brothers rm85l so i was going to give the 12 year old my wr/cr144 and keep the gg for myself.The gg is much smaller in stature and after todays ride on my wr/cr i have decided to give him the gg, the husky pulls clean from bottom right through even when in the wrong gear.the stuff we ride is clay gravel hills with a lot of off the throttle decents this outing did not blip the throttle to clean her out and basically was trying to foul the plug but could not.if you get your jetting sorted the mikuni just rips, no point jetting to someone elses specs beacause they are all different but i found that the leanest pilot i could find works best (15).

OK.... 4 hours on the new 144. The bike 100% RIPS, less a lean stumble @ a quick full throttle twist. Started @ 32.5, 460, 16-62 clip 3. Mega spooge out the back though. Went leaner to 30, 17-62 clip 3. This cleaned up the spooge and made the bike really crisp. Didn't make the lean wide open stumble change. Now to get the stumble out....

Walking speed, whack the throttle = stumble.

Half throttle, whack the throttle = same stumble. In my mind, this is telling me it's lean on the main, as I'm allready well past the pilot, and headed out of the needle. Correct?

Pics (cause I like pics) Please share your thoughts. Again, looks like a 470 main would be better than the 460 this was run on?

***NOTE*** This shot picked up on some oil droplets / light / something. What looks like detonation metal splattered on the rim of the plug isn't really there. In real life, it's discolored, but clean and smooth. This plug was in it the life of the bike (4.5 hours).


This is a brand new plug. Wide open through 1st, 2nd, 3rd, 4th, clutch pulled, kill switch held. It picked up a small amount of color.

Try the 470, i went to the 480

Thanks 88. It seems I'll be set up very similar to you once I get this straighten out. Based on my description of the location and delivery of the bog, would you agree it's more than likely a main jet issue?

I think the walking speed stumble is the low speed carb circuits ,with RB mods it fixes that issue, might try some more air screw . Not to sure about the half throttle being the main seems a little early but try a bigger main , it is easy.

Let me clarify... To get the stumble, I have to be @ full throttle (at the wrist). Te me, that's the main, regardless of speed or RPM. Starting is good, slow roll on's are smooth, and low to mid transition is good, so I have the perception that the pilot and needle circuits are solid at this point.

Yes Main

Before I got fed up with the mikuni and went keihin the symptoms you have were cured by raising the needle, the only problem was if the weather changed it was back to square one hence the reason I went keihin
Also try raising the powervalve arm as this can help with the midrange flatness

It's an RB modded TMX, so it's pretty good. Powervalve is raised 3/4 to the top.

What are your thoughts on the plug pics specifically? Thank you all for helping dial me it. I get this little hiccup cured, and it's trully an amazing bike I have here.....

ok so I finnaly got it all together and am very happy with the results. .8 base gasket 6chy-16-61 needle in the middle carb already RB'ed milled head = AWESOMENESS !!Did'nt have much seat time tonight but the leaness I felt with the stock needle is gone.That needle rock's, now all I need to do is get it up into the elevation and see how it performs. So far I don't even want to try the other needles I bought.
Thank's Dirtypirate for the help.
Tim.

Good deal,

Also, try moving your kicker back one tooth with the .8 gasket. Really helps and you won't have to lean forward as much to kick it.

Once you get your main/pilot dialed to your area. That bike ought to float the front wheel a couple feet off ground in all gears.

Another secret that I do: now take your needle back out. Take it to work and put it on a photocopier and copy a photo of it, actual size. Look to see if there are any steps when they cut the needle. You can see it better when you photo copy it. For some reason you can't see them just looking at the needle. If there is, lay needle beside the photocopy and mark it with a pencil. Put the needle in a drill press ( don't over tighten it to damage the top, just enough to hold it in the chuck) and use 1500 grit wet sand paper to get rid of any steps or ridges from cutting needle. You want a nice smooth transition. Little ridges affect a smooth throttle transition.

sounds exactly like my bike, same current setup except i dont have RB mods yet, only a PowerNow plate.

i ran some fast open areas a few weeks ago with the 470 in (which has been in for a while) but noticed it was stumbling at bit when pegged. i thought i might be a little fat still because i had spooge city for a while too. same previous setup but dropping to the 30P from 32.5P cleared that up. already had the 17-62 in.

this past weekend i went to a 460 main and the WFO stumble was way worse, so bad the bike had no power up top. i will go back to the 470 for this weekend but suspect, as TROFFER said, that a 480 might be the ticket. especially now that the temps are cooler. had a stupid hot summer.

i'm running a 0.7 base gasket and 112 leaded fuel. super snappy!

91 octane pump swill-dump the gay needle.the chy is worth a try=)

I think you will end up with a 480 , when RB does the carb he also bores it to a 39, so I think it likes a little more main.

Where did you get the CHY needle? The GAY is better than the stock but there is no way I could run on 91, I'm sure it would detonate.

Why would you detonate on 91 octane pump gas? We used to have 93 octane years ago but the State had the gas companie's reformulate the gas and now the highest you get is 91. I have never had a problem with detonation on pump gas and that is with all my past bikes and this one with milled heads for more compression. I only milled off 18 thousands on this head so I still have a relitively large squish area.Bought the needle from my friends cycle service shop and, they just ordered it from the people they get suzuki parts from.I think with your half clip washer you will have way more room to play with the chy 16-61.It has a really nice taper to it, not stepped like the stock needle.let me know if you need the Suzuki parts number.
Tim.

I have just put a 36mm PWK on my 144 and I am very happy with it . When you look at the benefits and the fact you can get most of your money back if you take it off and sell bike its a cheap mod.

Ever since my bike was new it would try to detonate on pump fuel especially in the low and mid range undera load. It would do this even with 93 no ethanol. I could get by by jetting rich but then I would lose performance. Mixing pump and race fuel 50/50 worked but was a hassle so I've used Sunoco 110 from the beginning.

So I can get the CHY needle at a Suzuki dealer or is there a better place?