How can I found out what my carb settings are ?

After receiving the needles & jets I saw the dealer had sent me a 180 MJ and not a 180 MAJ.!!! :)

Ring him up....ooops they say...

3 days later an empty envelope shows up with a little itty bitty hole in it and no 180 MAJ :D

Ring him up .... ooops they say...

1 day later ANOTHER empty envelope shows up with ANOTHER little itty bitty hole in it and no 180 MAJ :D:D:D

Rather pissed I ring up and they say ooops yet again.....

Today I recieved the 180 MAJ in an armour plated envelope with 3 pounds of duct tape wrapped around it. :D

Tonights the night...... :D

I'm coming to the UK soon Taff... so if it doesnt work watch your back !!


installed the 180MAJ and went for a few road runs run. It runs like snot for the first 1/8-1/4 throttle if I twist quickly. It bogs, almost dies, and then picks up rapidly from about 1/4 on if I let it recover. If I twist slowly, it runs far better, but still hesitates up to 1/4 throttle. Overall it is nowhere as crisp anywhere through the range as it was with WR timing and stock jetting. I can still pop a wheelie in 1'st and second by flicking my wrist, but only when I'm rolling and the throttle is over the 1/8-1/4 mark (guessing here as I havent marled my throttle, which i will be doing shortly).

I have played with the Pilot Screw in and out but it didnt seem to change performance much.

My current settings are

MAJ 180

MJ 165

PAJ 85

PJ 40

PS approx 2 turns

EML Clip #3 from top (I think). I know I know, I didnt write it down - DOH


Euro Exhaust & Header

Idle speed is as low as I can get it without it stalling.

From the manual and my reading, the problem would appear to be in the PJ/PAJ area as it is below 1/8 throttle that I have the problem. However, the overall performance curently is no improvement over WR timing and is probably worse.

Where do I go from here?

Having read the reviews, I was thinking about dropping the needle 1 clip as my interpretation is that it is rich (esp if I am on clip 3 from the top as I suspect), but will that affect the below 1/4 throttle ? I think so, yes cos you said, "drop the needle low enough and it will lean the pilot system". Am I on the right track ?

Also what about the EML vs the EMM ? The needle straight on the EML will make it richer across the board at higher revs, right. I think I will get that EMM needle anyway. However, I'm probably getting ahead of myself and out of my league here so would appreciate your help.

Lastly, the engine brace on the left suggestion for easy carb tweaking, is that so you dont have to disconnect the /"&ç%ing throttle cables when oiking the carb out???

[ November 09, 2001: Message edited by: The Missile ]

I just found out its no fun testing in a howling blzzard !! Its just started to snow here so all my efforts to have my bike ready for tomorrow are possibly for nothing !!

Anyway.... I was on clip 2 after all.

Its now on clip 1.

Much improved performance. at 1.5 PS

Test #1 Clip 1, 1,5 PS

to 1/8 throttle much better but still hesitating

1/4 stumbling, surging

Higher, much better, crisper

Test 2

1.0 PS

1/8 worse, big hesitation

1/4 Still stumbling

Higher same

Test 3

1.25 PS

1/8 better but hesitating

1/4 stumbling but better

Higher same

Test 4

1 5/8 PS

1/8 best setting but still hesitating

1/4 still stumbling a little

What next ???

ok mate

let's see what we've got.

i think that you're rich on the MJ by a few so if you have a 160 MJ fit it. if that works and the needle gives you gipp it will be because it needs to go up one clip. do one test at a time here. (there are two tests here).

if you've said it in the right place, about the misfire then i think your PAJ needs to come down to 75 from 85.

what i think is happening is that the MJ is rich and by bringing it down oyur needle can go back up. you may even need a 155MJ.

the bike you say is good from zero to 1/8 throttle which is proof that the **L needle straight is working. it leaves the PC area which unfortunately, until you try the main circuit first we can't be sure of.

if you don't have these jets, i suggest you try to order them. 160 + 155MJ. 38PJ. PAS or 65PAJ.

yes the two engine plates are on the left to facilitate carb pull out.

we may not get it right with these changes but you will know which way you're going.

when you come to the UK come up and see me. i'm 70 miles north of london.

be patient. if you get this right you've cut out 15 months development and saved yourself 80-90 tests.

to recap the area's that the needle effect. the straight portion **L will help during starting and the first yard or two. the clip position should only effect the 4th/5th gear roll on.

it's the MJ that, rather like a sweeper in defence at soccer goes along the back of the needle and pilot circuit boosting or undermining their work.

so if you lower the MJ you will be lowering the fuel whilst on the needle taper and indeed some of the PC jetting.


[ November 09, 2001: Message edited by: Taffy ]

Firstly thanks to JD. in an old post I saw how you remove your carb....undo the throttle cables at the throttle twister....very smart. This means you DONT have to remove the seat, tank, or black cover on the right side of the carb. I went one better?? and also moved the motor two motor braces to the left upon taffy suggestion. SO much easier !! to my jetting is....

NO APJ a la taffy

EMM clip 3

MAJ 180

MJ 160

PAS 75 (5/8 turn from seated)

PJ 40

Fuel Screw - Anything I wanted - no effect !!!

Performance all round was superb. Far better than the eml #1, 165MJ, 40PJ, 85PAJ that I had. 0 to 1/8 snap is back. 1/4 ish no hesitation. Takes off pretty well above there, but night testing cant go WOT yet. Wheelies in 1st, 2nd, 3'rd(almost) from closed throttle. No hesitation anywhere so far but... only test ridden not a real ride. Bike WAS thoroughly warmed though.

Temp is about 0C or 32F

So...with the fuel screw not making ANY difference and the bike running with it fully SCREWED IN... my assumption was PC is rich. I dropped the PJ to 38. Snap gone. BLOOOOEEER from 0 to 1/8 then picks up and is fine if I keep the revs high. Still no effect from the fuel screw setting.

hmmm.....I thought I was beginning to understand this stuff....

JD / Taffy / anyone any suggestions ??

MM (Missle Man),

I have been spending considerable time on the YZF forums (426 & 250).

On the 250 site, it was mentioned the air cut valve (octopus) actually interferes w/ adjusting the pilot system. It was mentioned turning their fuel screws have had ZERO effect on performance. When the octupus is removed, their fuel screws have an effect on jetting and have been adjusted. Some of the guys raved about how much better the bikes ran.

read the whole thing:

Several of us have removed the octopus. We install the (same year) YZ air jets.

Have you removed your octopus?

the missile

sounds like you're getting there!

today i've posted my latest tests and i've gone back to a 38PJ and the PAS is only 3/8th of a turn out which equates to #55 PAJ.

so if you're going to try that 38PJ why not turn the screw in from 5/8th (#75) to 1/2 (#65) and possibly 3/8th (#55)?

your gearing is very short so checking the top end (WOT and red line) will be a harder task.

remember any more changes of MJ will undermine your hard work setting up the bottom end.

you can use the engine backfire as an INDICATOR of your settings.

you don't mention any popping on the over run.

have you seen that i went down to a 150MJ today. that the bike then didn't appear to rev out a couple of times. could be i need to fit a 155MAJ.

get the top end sorted first or you'll never finish!


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