so.. i recently installed dyno jet kit stage 3, main jet 128. (got alot more power from it!!) went for a few test rides idles fine at 1600, but after acclerating fast and draws in  clutch the rpm jumps to 6k and stays there for a while until it lows back to normal, pretty annoying actually..

1600 is too high

1100-1300 is where you need to be. Slow it down and see what happens.

Quote from: Meukowi on July 20, 2018, 08:44:35 AM
idles fine at 1600,

I think in another thread I suggested the idle is set too high.

Normally hanging idle is caused by the idle being set too high. Set it when it's fully warmed up (we're talking 20 minutes ride time!) to about 1100-1200 rpm. Actually if you have set the idle mixture right, then it should idle at 1100-1200 rpm with the idle stop backed all the way out, as in this should be the slowest you can get the bike to idle. If it idles slower than this with the stop backed all the way out then most likely either the idle mixture is too lean or the pilot air orifice is clogged.

BTW you talk a lot about the DJ kit but such kits don't have a lot of fans on this site.

Quote from: mr72 on July 20, 2018, 09:06:26 AM

Quote from: Meukowi on July 20, 2018, 08:44:35 AM
idles fine at 1600,

I think in another thread I suggested the idle is set too high.

Normally hanging idle is caused by the idle being set too high. Set it when it's fully warmed up (we're talking 20 minutes ride time!) to about 1100-1200 rpm. Actually if you have set the idle mixture right, then it should idle at 1100-1200 rpm with the idle stop backed all the way out, as in this should be the slowest you can get the bike to idle. If it idles slower than this with the stop backed all the way out then most likely either the idle mixture is too lean or the pilot air orifice is clogged.

BTW you talk a lot about the DJ kit but such kits don't have a lot of fans on this site.

oh and that mixture screw.. where the heck is it? do i have to take carbs apart again to work with them? or are they in reach when carb is attached?

and about the dj kit, whats wrong with it? only kit i found around here in finland

Quote from: mr72 on July 20, 2018, 09:06:26 AM


I think in another thread I suggested the idle is set too high.

Normally hanging idle is caused by the idle being set too high.

But you used to claim the normal cause of a Hanging idle was an air leak, usually failure of the oring between the inlet stub and cylinder..

Nice to see you taking a more methodical approach to fault finding rather than making guesses and assumptions based on your limited experience.....keep it up 

Quote from: sledge on July 20, 2018, 10:33:48 AM
But you used to claim the normal cause of a Hanging idle was an air leak, usually failure of the oring between the inlet stub and cylinder..

Really? where did I say that? I don't remember. But of course I may have said that and many other things that are wrong in the past, and I may say other things that prove to be wrong now and in the future.

I will say an air leak at the intake boot o-ring is a major cause of vacuum leaks, and lean mixture. But I don't think lean mixture causes hanging idle, not directly. Mostly having vacuum leaks or a lean idle mixture may induce you to try and find fixes that result in hanging idle.

Lean mix and sucking air (vacuum leak) cause a hinging idle, because - well they both cause a lean mix where there is the highest vacuum - @ idle.
Cool.
Buddha.

Quote from: The Buddha on July 21, 2018, 10:53:07 AM
Lean mix and sucking air (vacuum leak) cause a hinging idle, because - well they both cause a lean mix where there is the highest vacuum - @ idle.

No they don't.

Lean mixture doesn't cause revs to increase. Lean mixture causes revs to drop.

And the vacuum is not highest at idle, it's highest at WOT. If it was highest at idle, the slides would be all the way up at idle.

Hanging idle is caused by the slides staying up when they should drop. They do this because the throttle is blocked open too much and allows air to continue to flow across the main (or mid) jet. It's literally part-throttle. But eventually vacuum drops enough that the slide drops down and closes the jet then you wind up with a "lean" idle because you are allowing air to flow past the throttle plate and the main jet is closed so it doesn't get (much/) any fuel added to it. The pilot jet is delivering fuel according to the amount of air coming in the pilot air orifice. So in fact it is lean only because the throttle stop is set too high. The "air leak" is through the throttle plate.

Close the throttle plate and adjust idle speed with the pilot mixture screw. It will idle the fastest with the best mixture. If it still idles too low then the pilot air orifice is probably clogged. If you just want it to idle at 1500 rpm then you need a bigger carb or at least one with a bigger pilot air supply.

There's no logic at all that explains how a lean idle leads to the revs hanging up on the way to idle.

Quote from: mr72 on July 21, 2018, 11:42:00 AM

And the vacuum is not highest at idle, it's highest at WOT. If it was highest at idle, the slides would be all the way up at idle.

At WOT you have ZERO vacuum (everything is at atmospheric pressure), at idle/closed throttle you have LOTS of vacuum because you are restricting the air.

Quote from: Beelzeboss on July 22, 2018, 06:03:36 PM

Quote from: mr72 on July 21, 2018, 11:42:00 AM

And the vacuum is not highest at idle, it's highest at WOT. If it was highest at idle, the slides would be all the way up at idle.

At WOT you have ZERO vacuum (everything is at atmospheric pressure), at idle/closed throttle you have LOTS of vacuum because you are restricting the air.

hmm, guess theres some vacuum, today i wotted myself to work, i run easily out of fuel with dj set, so i tried to pri more fuel but after 10sec or so it run totally out of fuel and stalled, shifted to 2-3rd gear and twisted petcock to on position and was good to go.. guess i should clean the filter, if there is any to help the fuel starvation..

Question! what would be the symptoms of too large main jet?

Lähetetty minun G8341 laitteesta Tapatalkilla

Dyno jet kits are fantasic. I'm a huge fan of them, they are the best bang for buck "bolt on HP" you can get. I have a DJ kit on my machine and we gained over 7hp on the dyno runs we did compared to  stock jetting and needles with a lunch box. It's all about that needle, you need that taper with the lunch box or your midrange will be shite.
Meukowi, are you running a k@n lunchbox and an open exhaust baffle? If so, the 128 jet should be ok with that set up but if you don't have those things the 128 is way, way too big. I started with the 132 Dj but it was too rich . So I went home swapped out to the 128DJ and there was a 6hp increase and air/fuel ratio at WOT was 13:1. With the 132Dj it was around 11 3/4:1.
If i was you I would check your float level and also check your pilot jets for cleanliness, don't poke thinks through them ie guitar srtings It will ruin them. Ultrasonic clean is best.
It's not the DJ kit causing your problems.

Quote from: Meukowi on July 20, 2018, 09:48:51 AM

oh and that mixture screw.. where the heck is it? do i have to take carbs apart again to work with them? or are they in reach when carb is attached?

They are on the underside of the carb just in front of the float bowl. You can adjust them on the bike but you need to modify a small screwdriver to do so.
They may have a small plug/bung covering them up so as to stop you from adjusting them. You can drill a small hole in them and pri them out but the carbs will have to be removed from the bike to do so.
Set them to 2 to 2 1/4 turns out for the DJ kit.

Quote from: Meukowi on July 22, 2018, 10:15:06 PM

Quote from: Beelzeboss on July 22, 2018, 06:03:36 PM

Quote from: mr72 on July 21, 2018, 11:42:00 AM

And the vacuum is not highest at idle, it's highest at WOT. If it was highest at idle, the slides would be all the way up at idle.

At WOT you have ZERO vacuum (everything is at atmospheric pressure), at idle/closed throttle you have LOTS of vacuum because you are restricting the air.

hmm, guess theres some vacuum, today i wotted myself to work, i run easily out of fuel with dj set, so i tried to pri more fuel but after 10sec or so it run totally out of fuel and stalled, shifted to 2-3rd gear and twisted petcock to on position and was good to go.. guess i should clean the filter, if there is any to help the fuel starvation..

Question! what would be the symptoms of too large main jet?

Lähetetty minun G8341 laitteesta Tapatalkilla

Correct. Only way you have highest vacuum @ WOT is if you pushed the slide down to the lowest position while holding WOT - never mind the dying motor, in the 2 sec before it will die, it will have the highest vacuum, in fact its gonna have so high vacuum, outer space may get jealous.
Anyway, the bike is lean, and lean misfire can result, but it also will be interspersed with a high idle.
Also 1600 isn't a high idle rpm, I set my bikes high, because the oil pressure this bike makes is dismal, if you're city commuting, that extra bit of oil pressure can help. So 1500 and up isn't too crazy IMHO - but sort the jetting out, if its 1500 on a cold winter day 60 sec after starting it, it should be 1500 30 sec after starting on a hot summer day.
Jetting should be separate from the idle rpm. It should burn nice and chocolate at the plug regardless of ambient temp/humidity etc.
Cool.
Buddha.