C
crankcase
Guest
can anyone tell me what the diference is between changing the needle
and raising the needle
and raising the needle
S
S.T.Chapman
Guest
Re: mikuni carb
differing profile
lift the needle so many times then progress to the next needle up
differing profile
lift the needle so many times then progress to the next needle up
B
BrunoKatz WW1FighterPilot
Guest
Re: mikuni carb
I originally had my needle [no.97] set in the middle groove. I have an evo engine, i ran it on this setting for about three months taking plug readings at various throttle openings. I could never get the plugs darker than a lightish grey with the needle in this slot.
Most of your day to day running is done at a quater to three quaters throttle, therefore it is fairly important to get your needle settings right. First of all, you should set the idle running and the full throttle running correctly by way of installing the right jets and correct adjustment of the idle circuit. Raising the needle a notch will allow more fuel in making it richer and obviously lowering it will lean it out. I raised my needle by one notch which greatly improved the acceleration, stopped all exhaust popping and turned the plugs a mid tan colour. Slightly rich maybe, but far better than too lean. I did notice a slight drop in fuel mileage but only about five to ten miles down per tankfull.
I originally had my needle [no.97] set in the middle groove. I have an evo engine, i ran it on this setting for about three months taking plug readings at various throttle openings. I could never get the plugs darker than a lightish grey with the needle in this slot.
Most of your day to day running is done at a quater to three quaters throttle, therefore it is fairly important to get your needle settings right. First of all, you should set the idle running and the full throttle running correctly by way of installing the right jets and correct adjustment of the idle circuit. Raising the needle a notch will allow more fuel in making it richer and obviously lowering it will lean it out. I raised my needle by one notch which greatly improved the acceleration, stopped all exhaust popping and turned the plugs a mid tan colour. Slightly rich maybe, but far better than too lean. I did notice a slight drop in fuel mileage but only about five to ten miles down per tankfull.
B
BrunoKatz WW1FighterPilot
Guest
Re: mikuni carb
Can you tell me what type and year your engine is? I may be able to help you get more or less the right settings to save you some time if you require this.
Can you tell me what type and year your engine is? I may be able to help you get more or less the right settings to save you some time if you require this.
S
S.T.Chapman
Guest
Re: mikuni carb
you can come and sort mine out while your at it Bruno
you can come and sort mine out while your at it Bruno
B
BrunoKatz WW1FighterPilot
Guest
Re: mikuni carb
Simon, don`t be so bloody lazy, you`re more capaable than me at sorting them out!
Simon, don`t be so bloody lazy, you`re more capaable than me at sorting them out!
C
crankcase
Guest
Re: mikuni carb
yes banquo
its a 104 stroker evo ,hi comp heads,mikuni45 ,idle jet 25 air screw runs best 1-1/2 turns out, suffering with detonation under accelaration,plugs are allmost white,main jet is 175, needle is as comes standard
yes banquo
its a 104 stroker evo ,hi comp heads,mikuni45 ,idle jet 25 air screw runs best 1-1/2 turns out, suffering with detonation under accelaration,plugs are allmost white,main jet is 175, needle is as comes standard
S
S.T.Chapman
Guest
Re: mikuni carb
those are the setting more or less for an 88" not a 103"
those are the setting more or less for an 88" not a 103"
B
BrunoKatz WW1FighterPilot
Guest
Re: mikuni carb
My name is Bruno, not Banquo, think he`s a Jock!
Right, as Simon says [hey, you could turn that into a song?] don`t think your jets are large enough, well maybe the main is o.k. but can you tell me what size needle you`re running and what notch it`s on for starters? Also the pump jet size would be usefull. We gotta get those plugs browned off a bit.
My name is Bruno, not Banquo, think he`s a Jock!
Right, as Simon says [hey, you could turn that into a song?] don`t think your jets are large enough, well maybe the main is o.k. but can you tell me what size needle you`re running and what notch it`s on for starters? Also the pump jet size would be usefull. We gotta get those plugs browned off a bit.
S
S.T.Chapman
Guest
Re: mikuni carb
its the primary its too small
nearly 3/4 of your running is off main jet and on primary
its the primary its too small
nearly 3/4 of your running is off main jet and on primary
B
BrunoKatz WW1FighterPilot
Guest
Re: mikuni carb
Hmmm, what concerns me Simon is, his needle size and/or notch position. If he`s banging on acceleration then that points to weakness and as the needle controls mixture from just off idle to roughly three quaters throttle then i would say he needs to look at this too, and also his pump jet size and its length of operating stroke?
Hmmm, what concerns me Simon is, his needle size and/or notch position. If he`s banging on acceleration then that points to weakness and as the needle controls mixture from just off idle to roughly three quaters throttle then i would say he needs to look at this too, and also his pump jet size and its length of operating stroke?
S
S.T.Chapman
Guest
Re: mikuni carb
you have to start somewhere and if the basics arnt right then yer stuffed and might as well give up.
basically I dont know the right jet sizes for that engine, the internet is a wonderfull source
bear in mind if you try to do the first 3/4 throttle range on main then it wont work, its running weak to start with
then again with totally white plugs i'd make dammed sure the inlet manifold wasnt leaking
you have to start somewhere and if the basics arnt right then yer stuffed and might as well give up.
basically I dont know the right jet sizes for that engine, the internet is a wonderfull source
bear in mind if you try to do the first 3/4 throttle range on main then it wont work, its running weak to start with
then again with totally white plugs i'd make dammed sure the inlet manifold wasnt leaking
B
BrunoKatz WW1FighterPilot
Guest
Re: mikuni carb
Hmmm, yes agreed mate, s`funny he hasn`t been back on has he? Shall we wait until he comes back with more info?
Hmmm, yes agreed mate, s`funny he hasn`t been back on has he? Shall we wait until he comes back with more info?
C
crankcase
Guest
Re: mikuni carb
hello again men ,sorry about calling you banquo bruno
i was running a25 pilot jet
97 needle,3rd notch down
air screw 1 1/4 out pump jet 60
have just tryed 27.5 pilot
96 needle 2nd notch but realy hard to startand now running very hot indeed
exausts starting to glow .
how about back to 97 needle 3rd notch down???
hello again men ,sorry about calling you banquo bruno
i was running a25 pilot jet
97 needle,3rd notch down
air screw 1 1/4 out pump jet 60
have just tryed 27.5 pilot
96 needle 2nd notch but realy hard to startand now running very hot indeed
exausts starting to glow .
how about back to 97 needle 3rd notch down???
S
S.T.Chapman
Guest
Re: mikuni carb
how about doing something with that standad 25 primary thats your problem imo
how about doing something with that standad 25 primary thats your problem imo
B
BrunoKatz WW1FighterPilot
Guest
Re: mikuni carb
Yeah i agree with Simon, take your pilot up to 27.5 for starters, try the 97 needle up one notch from where you have it now and try it again. The pump jet sounds o.k. have you set its stroke to start soon as you open throttle and cut at about 3/4 open?
Yeah i agree with Simon, take your pilot up to 27.5 for starters, try the 97 needle up one notch from where you have it now and try it again. The pump jet sounds o.k. have you set its stroke to start soon as you open throttle and cut at about 3/4 open?
H
hellon2
Guest
Re: mikuni carb
Hi
I have just acquired a '99 softail heritage, 88cu with stage one, and Mukuni flat slide carb. The carb has an adjusting screw on it brought out on a short flexible cable with small knurled wheel - clearly designed for tinkering with!
I am told this is the tick-over adjust and sure enough tweeking it adjusts the tick-over, so when its nice an warmed up i can get a real slow put-put (long pause) put-put as per HD should sound. :p
However, having read the thread above, I am bit concerned if I am tinkering with other aspects of the carburation, i have noticed some back-firing on over-run occasionally. Will slow tick-over mean the engine is running lean for example?
Also, i am pondering replacing the airfilter, i presume there is a hi-performance filter inside what looks like a stock HD cover at the moment. Anyone got views on hyper-chargers?
Rob (not very techy)
Hi
I have just acquired a '99 softail heritage, 88cu with stage one, and Mukuni flat slide carb. The carb has an adjusting screw on it brought out on a short flexible cable with small knurled wheel - clearly designed for tinkering with!
I am told this is the tick-over adjust and sure enough tweeking it adjusts the tick-over, so when its nice an warmed up i can get a real slow put-put (long pause) put-put as per HD should sound. :p
However, having read the thread above, I am bit concerned if I am tinkering with other aspects of the carburation, i have noticed some back-firing on over-run occasionally. Will slow tick-over mean the engine is running lean for example?
Also, i am pondering replacing the airfilter, i presume there is a hi-performance filter inside what looks like a stock HD cover at the moment. Anyone got views on hyper-chargers?
Rob (not very techy)
S
S.T.Chapman
Guest
Re: mikuni carb
it is the tickover, dont turn lower than 1000rpm.
hyperchargers dont do anything.
it is the tickover, dont turn lower than 1000rpm.
hyperchargers dont do anything.
B
BrunoKatz WW1FighterPilot
Guest
Re: mikuni carb
Hellon, as Simon says [No he`s not simple] don`t turn your RPM down lower that 1000 cos you will sod up your oil pump if you let it do a Shovelhead tickover. If you`re popping on the over run, could mean you`re running lean on the pilot jet. Try re-settting it, remember, on a mikuni you turn the idle screw in to richen it up. What colour are your plugs by the way?
Hellon, as Simon says [No he`s not simple] don`t turn your RPM down lower that 1000 cos you will sod up your oil pump if you let it do a Shovelhead tickover. If you`re popping on the over run, could mean you`re running lean on the pilot jet. Try re-settting it, remember, on a mikuni you turn the idle screw in to richen it up. What colour are your plugs by the way?
W
woody's dyna
Guest
Re: mikuni carb
forget Hyperchargers, look good but no noticeable change in performance.
Have a look on the mikuni website good helpfull info.
www.mikuni.com
forget Hyperchargers, look good but no noticeable change in performance.
Have a look on the mikuni website good helpfull info.
www.mikuni.com