Carb Adjustments

[BIGMO]

Carbs have been rebuilt. New slides and diaphrams. Morley Muscle Jet kit stage 7 needles. stock jets.
I am getting not great fuel mileage, approx. 70-80 miles till light comes on. I am wondering which should I try first. Screwing my A/F screws in a half turn at a time to get better mileage. Or should I adjust the needle one clip closer to blunt end to put needle in the carb more. Which do you think has more effect on fuel mileage. It runs pretty good just bad mileage. wanting to try one then run a tank through it and test to see if it gets better. just wondering which you guys would start with, or am I barking up the wrong tree? Thanks for any ideas.

 

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Help us, Help you:

Altitude
Main Size
Clip Position on your stg 7 needles
Turns out from bottomed on A/F screws
Stg 7 or stock slide springs
Drilled or stock slides

 

[BIGMO]

Elevation: 797 FT (243 M)
I beleive the mains are 157s. (stock?)
clip position will have to get tonight but i think its 3 from blunt end
A/F screws 2 1/2 turns out
hafta guess at the springs cause i didnt install the stage 7 kit (which is now Morley kit)
slides are drilled to accept stage 7 needle.

What Im really wanting to know is which affects fuel mileage more, needles or A/F screws. But any input is great. maybe my main size is too big? I thought id start with the easiest with Needles and A/F screws but not even sure if thats the way to go.

 

[gamorg02]

Elevation: 797 FT (243 M)
I beleive the mains are 157s. (stock?)
clip position will have to get tonight but i think its 3 from blunt end
A/F screws 2 1/2 turns out
hafta guess at the springs cause i didnt install the stage 7 kit (which is now Morley kit)
slides are drilled to accept stage 7 needle.

What Im really wanting to know is which affects fuel mileage more, needles or A/F screws. But any input is great. maybe my main size is too big? I thought id start with the easiest with Needles and A/F screws but not even sure if thats the way to go.

Slides don't have to be drilled to accept the stage7 needles, the drilling should have been done to the side of that!

depends on where u are cruising at and what you're doing with your max. if you are in the 6k and above range al ot, thats mains, i fyou are under 3k a lot thats pilot circuit, if you are in the 3 - 6 k range a lot thats needles.

 

[BIGMO]

Slides are drilled correct. Maleko rebuilt em, it just came out wrong sounding. But u get the idea. yes slides drilled.

Much of my cruising is low rpm. not alot of Vboost, in town riding. Probably around the 3000 - 4500 range. Sounds like you are saying the needles should be my first stop. Ill drop em a clip and see what happens after a tank full. Just wanted to get an idea of where to start. thanks.

Anyone using the factory pro needles? they seems to have a more even taper. wonder what the difference in performance is between the stage 7 and Factory pros.

 

[gamorg02]

Slides are drilled correct. Maleko rebuilt em, it just came out wrong sounding. But u get the idea. yes slides drilled.

then they're done right. i follow!

Much of my cruising is low rpm. not alot of Vboost, in town riding. Probably around the 3000 - 4500 range. Sounds like you are saying the needles should be my first stop. Ill drop em a clip and see what happens after a tank full. Just wanted to get an idea of where to start. thanks.

i think thats borderline between pilot and needle. do your needles and see what it yields. you are too lean if you can't cruise deliberatly. also cruise at those speeds for maybe like 5 miles if u can and do a plug test.

Anyone using the factory pro needles? they seems to have a more even taper. wonder what the difference in performance is between the stage 7 and Factory pros.

no idea, someone with more knowledge would have to attest to that. certain kits must like that type of taper.

all IMO

 

[BIGMO]

Thanks Garret, I need to change plugs yet this year so ill adjust needles and new plugs for plug test and see where that gets me.

 

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I'm sure mark or sean will chime in but i'll throw my two cents out there while i'm bored.

Stock mains should put you really close with stg 7 needles at your elevation. 152.5 is stock, not 157.5.

You main should be properly selected before tuning the rest of your carbs, otherwise your wasting your time. (float height too)

needle adjustments make a bid difference in mpg. Most people spent alot of time in the midrange, midrange is mostly controlled by the needle.

I'd verify with whoever installed you kit what mains are in there. If stock 152.5 I'd say leave em. Check the float levels, this can be done on the bike using clear hose.

Once that is done and all in check then tackle the needles. You bascially want the needle to be as lean as possible with the bike still running right. Lean would be moving the clip towards the blunt end. You can even buy a shim kit that helps you to dial in the needle even more precisely than just moving it a whole clip position at a time. (pauls precision shim kit).

Yes, the A/F screws have an MPG too but I think you will notice the biggest changes from changes to the needle (if mains and floats are good)

Just my opinions tho'. I'm still learning here.


EDIT: I see Mark rebuilt your carbs for ya. If anyone around here knows what they are doing with the carbs it's Mark and Sean. I'm sure he's got you straight on the mains and floats. Worst case scenario should be just some fine tuning with the needle shims and a/f screws. Riding habits make a huge difference in MPG. Don't expect to get 40+MPG beating on the bike around town. Open road, steady cruising 65-80 mph no problem but not horsin' around.

 

[one2dmax]

Float height settings can make a bit difference. You want to adjust the needles down (towards the blunt end) until the bike doesn't quite run right then move back up 1/2 size (add washer) until you get smooth running.

We used the factory pro needles on the very first sets when we were designing the kits. They are very tapered but not really going to improve your setup.

Sean

 

[BIGMO]

Just went through my emails from way back when the carbs were rebuilt. Mark says they are Mikuni 155's .

 

[gamorg02]

np. take sean's advice, he knows his shit. if mark recently did your carbs i'm sure ur fine.

 

[BIGMO]

Ya its been a year or two since he rebuilt em.

Sean what thickness washer you using for a spacer?

 

[gamorg02]

Ya its been a year or two since he rebuilt em.

Sean what thickness washer you using for a spacer?

his are about .018"

radioshack washers are about .020 - .022". i had one that was .028, but didn't use that one. mine were all within 5 ten-thousandths.

 

[one2dmax]

correct, pauls shims are ok but you can get them plenty close if you measure a few out.

Sean

 

[dannymax]

I found several R/S washers that mic'd to .018" after the tiny stamping burr on the edges was removed. They're only $1.99 a bag, compared to the $40 'precision' kits.

 

[gamorg02]

i picked up two bags. for that price i didn't care. mine didn't have the burr. looked very very closely.

 

[Redbone]

What is the Radioi Shack part number? May need to pick a bag up sometime.

 

[gamorg02]

only thing of washers in the whole store.

http://www.radioshack.com/product/index.jsp?productId=2103391

 

[dannymax]

What is the Radioi Shack part number? May need to pick a bag up sometime.

I just asked them for a $1.99 bag of little washers and the kid grabbed them right away.

You're running stock set-up Brian?

 

[BIGMO]

Update. I pulled my diaphrams last night and all my eclips are one the 4TH notch from blunt end. Also last time i messsed with them, im not even sure how this happened, the back two carbs when i pulled off the covers the little washers that are supposed to be under the little springs under the big plastic screw, were laying in the cover. Both carbs. I dont know wtf happened there. so i put each clip on the 3rd notch from end (leaving two open notches to blunt end) and took it out and man it ran like shit. i came back pulled one of the carbs and noticed i had the spacer with the tit on it upside down. i put it right and left them all at 3rd clip. order went : spaceer with tit towards carb, then eclip, then washer, then small spring then big plastic screw.

this morning running at apprx. 2700 to 4000 rpms the bike ran flat. and kinda surged a bit. if i held it at each rpm it just blatttt ran flat. im gonna move them back to the 4th clip but what is this telling me? that I need to go up one size on my main jets? Im trying to relieve my poor fuel mileage problem.