OEM Carbs? Post your setup

[speedcostsmoney]

oops forgot mixture screws set at 2 1/2 turns out, if your mixture screws are at 3 turns and higher your mainjet is too small hint hint

 

[tugla]

187 ft above sea level
main jet 185 dynojet - 172.5 mikuni
stage 7 needle 4th from square end
stage 7 springs
slides drilled
PAJ 1 & 2 stock
no air correctors
k & n indepedent air filters
2 inch copper velocity stack with X- WING inside copper pipe
v-boost stock
185 km or 114 miles then the little RED LIGHT goes on
stage 7 needle on clip 5 do 130 km only before red light but damn the bike pulls arms off
185 main jet a little rich top end dropped to 180 gonna see how it goes
UFO 4 INTO 2 EXHAUST 12" CANISTERS 2 1/2" HOLE

Interesting set up.....I'd say 185 rich,awesome you get that kind of mileage with that jet and needle position......cool unk:
So you gonna run 180 with needle on clip 5 from blunt/ square end.....can't wait to hear your fuel mileage then. Are you taking it real easy to get that kinda numbers...

Remind me if we go for a cruise not to wait til you fuel up haha I will be for sure on side of the road. Red light on about 170 km but that's cruising at 122-125 kph

 

[Rusty McNeil]

Interesting set up.....I'd say 185 rich,awesome you get that kind of mileage with that jet and needle position......cool unk:
So you gonna run 180 with needle on clip 5 from blunt/ square end.....can't wait to hear your fuel mileage then. Are you taking it real easy to get that kinda numbers...

Remind me if we go for a cruise not to wait til you fuel up haha I will be for sure on side of the road. Red light on about 170 km but that's cruising at 122-125 kph

Interesting indeed, no air correctors using pod filters?????

Your jetting is big enough for a typical big bore 160-180 horse motor.

How do your plugs look?

 

[Rusty McNeil]

oops forgot mixture screws set at 2 1/2 turns out, if your mixture screws are at 3 turns and higher your mainjet is too small hint hint

Actually it would be your pilot fuel jet that would be to small. Main jet has nothing to do with the mixture screw idle circuit.

Pilot fuel jet controls idle and just off idle fuel mixture.
Pilot fuel is that tiny one under one of the rubber plugs that comes stock in a 37.5 size. Super easy to have this one get plugged up.
It more or less sets a "range of adjustability" for the idle mixture screws.

When I went with the big motor I ended up bumping it up to a #40 to get my mixture screws back down to the 3 to 3 1/2 range, with the 37.5 I had to run the screws out to almost 5 turns to get it to run right, which is so close to the 6 or 7 turns it takes to totally disengae the threads it made me nervous that I might lose them altogether...

 

[Rusty McNeil]

Remember to synchronize the carbs each time you plop the rack back on. First pick out the proper main jets, then focus on the needles, and finalize the effort with AFR adjustments. note that tuning is based on throttle position not motor rpms.

VMax Outlaw's CV Carb Tuning Steps
Ian Williams' Mikuni Motorcycle Carburetor Theory 101
Tuning Your Carburetor For Optimal Performance And Fuel Efficiency
MAC Tuning Guide
The everything on carbs bible!



Regards from my Taptalking Hercules Android

Great post.
The first link is a super one, its actually "Factory's" info from their website.

But there all good, and taken as a whole ought to be required reading.

 

[srk468]

That is an awesome article Rusty I'll be honest though I'd have never got my bike tuned if I wouldn't have installed my wideband... Tried throttle chopping it and couldn't get a handle on it and I've had quite a bit of experience reading plugs but I thought they looked good but the bike wasn't running what I thought it should... As soon as the wideband was on there I realized that I was pig rich, went back to stock jetting and even that was rich but closer and the bike responded by going almost 2 tenths faster at the track... Not saying everyone should run out and buy a wideband (I knew I was gonna be spraying so I needed it anyways) but it sure made my bike easier to tune...

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[Rusty McNeil]

That is an awesome article Rusty I'll be honest though I'd have never got my bike tuned if I wouldn't have installed my wideband... Tried throttle chopping it and couldn't get a handle on it and I've had quite a bit of experience reading plugs but I thought they looked good but the bike wasn't running what I thought it should... As soon as the wideband was on there I realized that I was pig rich, went back to stock jetting and even that was rich but closer and the bike responded by going almost 2 tenths faster at the track... Not saying everyone should run out and buy a wideband (I knew I was gonna be spraying so I needed it anyways) but it sure made my bike easier to tune...

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Right on Scott, and I agree with the wideband, as much as I "thought" I learned from past experience and all the literature and articles I've read I don't think I'd be there yet without the aid of the wideband.

So much of tuning guidelines rely on "Subjective" judgements of what it "Feels" like that even with all the info in the world it's tough for anyone but a real pro that's done a lot of it to make corrections based on subjective observations...

Some of the other articles that go into what effects and WHERE in the throttle opening the float level has it's effects are especially handy....From what I've gleaned float level is not so much about whether the bowl runs dry or not, it's about how the level effects head pressure and the amount of effort required to draw fuel from the carb, thereby affecting a/f mixture, mostly at off idle, cruise, and when "whacking the throttle" from a cruise position"

I have yet to find a white paper on our particular carbs that clearly explain the relationship of what ours do with PAJ 1 & 2, most seem to refer to just one PAJ jet.

Between Mark, Sean and a few others on here, plus a lot of experimentation I think I almost understand those now.....maybe......

One thing to watch out for is that a lot of articles don't make it super clear that they are talking about Non CV carbs, (flat slides) like are found on many dirt bikes...gotta read, read, read, and then try to apply itunk:

 

[srk468]

Right on Scott, and I agree with the wideband, as much as I "thought" I learned from past experience and all the literature and articles I've read I don't think I'd be there yet without the aid of the wideband.

So much of tuning guidelines rely on "Subjective" judgements of what it "Feels" like that even with all the info in the world it's tough for anyone but a real pro that's done a lot of it to make corrections based on subjective observations...

Some of the other articles that go into what effects and WHERE in the throttle opening the float level has it's effects are especially handy....From what I've gleaned float level is not so much about whether the bowl runs dry or not, it's about how the level effects head pressure and the amount of effort required to draw fuel from the carb, thereby affecting a/f mixture, mostly at off idle, cruise, and when "whacking the throttle" from a cruise position"

I have yet to find a white paper on our particular carbs that clearly explain the relationship of what ours do with PAJ 1 & 2, most seem to refer to just one PAJ jet.

Between Mark, Sean and a few others on here, plus a lot of experimentation I think I almost understand those now.....maybe......

One thing to watch out for is that a lot of articles don't make it super clear that they are talking about Non CV carbs, (flat slides) like are found on many dirt bikes...gotta read, read, read, and then try to apply itunk:

Home run post there Rusty!! I don't claim to be an expert but I'm fairly perceptive for a hillbilly LOL Everything is trial and error with these carbs and they are never perfect but you can get to a pretty linear setup that works well under most conditions.. I think most people on here have the same line of thinking that I used to have and that had me fatter than hell... Your in a very limited area Rusty (even less available info) with a large displacement engine especially with extra stroke that will effect efficiency at lower rpms so I wouldn't even attempt it without a wideband but I'm glad you seem to have it worked out now

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[speedcostsmoney]

180 main jet dynojet too rich, OOPS forgot to mention got somesecondary jets installed on the side of the air filters, DIAL A JET from THUNDERPRODUCTS.COM. when started the stage 7 tuning the main was too small because of the exhausts would pull too much so went up to 185 dynojet, but now with the secondary jets too rich mid and top end but the bike runs ok . gonna buy me some 160 MIKUNI jets, drop them in and go for a road test. on cold morning runs the secondary jet really helps, choke 30 seconds then punch the throttle on take off no problems, but just a stage 7 i really have to warm up the engine or else the vmax does not like WOT on launch

 

[Traumahawk]

180 main jet dynojet too rich, OOPS forgot to mention got somesecondary jets installed on the side of the air filters, DIAL A JET from THUNDERPRODUCTS.COM. when started the stage 7 tuning the main was too small because of the exhausts would pull too much so went up to 185 dynojet, but now with the secondary jets too rich mid and top end but the bike runs ok . gonna buy me some 160 MIKUNI jets, drop them in and go for a road test. on cold morning runs the secondary jet really helps, choke 30 seconds then punch the throttle on take off no problems, but just a stage 7 i really have to warm up the engine or else the vmax does not like WOT on launch

Ive heard a little bit about the dial a jets.....how are they? Do they work well?

 

[speedcostsmoney]

the plug electrode clean you can see the steel
ceramic close to spark white
middle of the ceramic black
bottom of ceramic really really black
edge of thread a little soot deposit
road test warm up bike a bit, well try to it's a little cold around here so bike doesn't really get to operating temperature, then punch the hell out of the throttle then stop check spark plugs in first gear,
correct me if i'm wrong but read somewhere recently that you have to be in 4th or 5th gear for 8 to 10 seconds to properly do the test
i just gun it in first, then check spark plugs
waiting for mikuni jets to come in later on the week gonna do some more tests
thx for the help

 

[speedcostsmoney]

i like em it really improves the throttle reponse especially when it cold, you have to go down two jet sizes before you install them so really helps gas millage, you get a nice constant power curve, no drops, crisp throttle response, just got to get workin together

just installed the vmax airbox rubber boots to my K & N PODS, 2 1/2 inch long for front pods 2 inch long for rear pods to clear the faux tank when closed, it really improves the kick in the pants feeling, the vmax just wants to fly

 

[tugla]

I usually run it up to top of third or forth......get nice pull and good plug indication. But everyone has their own way to read plugs.....seems to work for you.let us know what your new mileage is....

 

[speedcostsmoney]

dropped in the 160 mikuni main jets, dial a jet at medium setting, running a little lean at 8000 rpm , still got a little tweaking but getting close. gonna make the the dial a jet richer got two more settings richer, without touching the carbs

 

[invalidsession]

150-250 asl
kerker 4-1
stg 7
needles 3rd from blunt
2 1/4 turns out
160dj
cop's, air correctors, k&n individual filters, slightly raised up with rubber stacks
slides drilled
39-43mpg highway at 75 mph
unk:unk:

Are you serious Tug ?Avg 41mpg ? My max is 1420cc and running a stage 7 kit with a Kerker 4/1. I don't ride her real hard but I'm seeing 20 / 25 mpg at best. V Boost is standard and operational. Are you really getting that gas mileage ? My last fill to warning light was only 90 miles after a good hard slog into the wind but even so, you are killing my bike on mpg's
Chris.

 

[tugla]

yup I've riden with a few forum guys they can confirm that.....I've added a few pounds so not as good....maybe 39 hahah 41 was best 40 avg but taking it real easy all highway

 

[tugla]

dropped in the 160 mikuni main jets, dial a jet at medium setting, running a little lean at 8000 rpm , still got a little tweaking but getting close. gonna make the the dial a jet richer got two more settings richer, without touching the carbs

u got picks of your dialjet set up.

so u think about at jet 153 /155 right now?

 

[tugla]

the 1420 I'm sure drinks the juice but should be ableoto get better mpg a bit

 

[invalidsession]

Ima thinking the same mate. My last fill up was 80 miles until the light clipped in and drank 3.7 gallons to fill up. Not good. I've also noticed a fair bit of spitting back through the air filters and exhaust of late, nothing nasty and she still pulls like a freight train on steroids but I don't like it in town riding. I did install a set of NGK iridium plugs recently and they seemed to help but I have to wonder if the high temperatures here in the midwest just now are causing an issue ? There's no one around here I trust to tune this leviathan properly so I suppose it's down to me and the good nature of the advice and wisdom of this forum.
Thanks guys.

Chris.

 

[Diablotin]

I'm used to get 80 miles in city driving with the traffic and pretty high temperatures here. Only on highways I will exceed the 100 miles.
I'm a bit reach for sure but as I can see other guys around here are getting the same mileage too.

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