Carb needles?

[maddog1]

I'm working on an 80 xs11 with pod filters and stock
exhaust. It belongs to a friend of mine.

Anyway. I put one size larger pilot jet and went up
two sizes on the mains. It runs a lot better but it acts
like it needs the needle raised up some.

(has a light bog at 1/4 throttle but screams when you
open it up.

My questions are: How does one change the needle
height? 2) What's the best method of adjusting those
mixture screws?

I tried a vacume guage but it wobbled all over the place.


Thanks in advance.


Matt

[Winterhawk]

Braden hooks the sync gauges up to the bike. Then adjusts each mixture screw while syncing the carbs. One by one he turns in the mixture screws untill losing rpm. Then back them out to achive highest and smoothest rpm. Doing each one and making sure it stays in sync at the same time.

I think they are using thin washers to raise the needle some on those.

[chevy45412001]

tiny washer

on my XJ the needle height was not adjustable.A good mechanic gave me the VARY SMALL (couldn't give you the size) lock washers. I made them flat with pliers per his instructions.Remove the carb tops,pulled off the slides with the needles,IIRC removed small screw that holds in the needle (might be two small screws).Pull out needle from the rubber part , put washer on needle, reinstall. Reapeat for all carbs. I think the lock washer was used because a flat washer would be to big on the outside diameter to fit right.Hope this helps a little.

[dntemp_ca]

I tried the Braden technique for adjusting mixture screws. I had them all set at about 1 3/4 turns out from lightly seated. I turned 'em out about 1 1/2 turns...nothing. Turned 'em in about 1 turn...nothing. What's up with that? Anyway, she runs pretty good, so I'm leaving it alone until I can find a colortune. My bike pulls good at low and mid range, but I've never got to redline. Reasons being: 1) it seems to flatten out after about 6500 rpm 2) I don't really need to be going anywhere that fast 3) I don't want to hurt it.

[maddog1]

This XS11 is still giving fits. I put a washer under the needle,
installed 45 pilot and 115 mains.

It screams and idles great but just off idle, it bogs a little
and I get a backfire (carb) occasionally. It just dosen't have
power when gently pulling away from a stop.

I'm starting to hate this thing!

[stal871]

shouldn't have to adjust needles. that's getting pretty technical. with pod filters and stock exhaust, i'd put 120 mains in all the way across, leave the stock pilot jets in, and set the idle screws at 1 1/4-1 1/2 turn all the way across. also, make sure your rubber boots on the engine side are tight and not cracked. if they are cracked, take em off and clean em and spray-paint the outsides with some of that rubberized coating you can buy at the hdwe store.

[ratbyk]

Bogging

Maddog1, if it is popping back out through the carbs at low speed as you crack the throttle, this is definitely a lean condition at that speed range. Mains have not even started to produce fuel down at low speed so richening the mains is not going to help.
Definitely go back through the pilot/idle circuits and make sure that they definitely "CLEAN" all the way to idle mixture screws on top of the carbs next to the intake boots/manifolds. When the carb is disassembled with the pilot cover screw "AND" the pilot jet out and idle mixture screws out you should be able pass carb cleaner(or lacquer thinner) through the entire way. If not there is still dirt in the system and it is never going to work right at low engine speed.
Another cause for spit back at low speed is a lean condition caused by the float level being set too low.
Ken/Sooke

[Winterhawk]

Ok, I have an idea, next time the carbs are off seal the end of the manifolds. Put about 5 or 10 psi in it thru the sync. nipples. Spray soapy water around it and look for bubbles. You might have intake manifold leaks maybe.

I can't tell any difference when I adjust my mixture screws either.

I saw Braden do 2 bikes now and when he does it I can hear the changes in the motor. What gives? beats me....LOL

Might make sure you don't have the funky K+L pilot jets in it.
Also look for any kinked hoses too.

[Badger]

Needles

Hi maddog1,
I have a 1980 standard/G [I think] that I had a tussel with in the carb department, but I learnt a few things along the way that might help you now.

I could never get more than 6500/7000 rpm out of it [I've had it ten years now] but as someone else said [pararphrasing] 'that was fast enough'. There was also a weird response to rolling the throttle off slightly at high rpm...it was like the throttle had been fully closed and opened again.

Then recently [after reading a lot of stuff on this site], I went after and vastly improved the 2nd gear problem but caused a tuning/fault problem which no-one could figure out [probably because no-one had ever got one needle out of line with the others before], that got me deep into the tuning issue.

Once I got the needle back in line, I started playing with the settings [starting from 125 mains and 42.5 pilots] and yes mine are the adjustable slides.

I got tricked with the needles because it turns out that the mains were way too small and the only way someone could get half decent performance was to assemble the needles back to front so they were [way] high in the slide.

My first move was to drop the needles to the standard mid groove setting [I was convinced the bike was getting too much fuel as the standard jetting is supposed to be 115 1 & 4 and 120 2 & 3].

This produced a masive flat spot off idle and reduced top end [struggled to pull 6k]. So I put the needles one groove higher than where they were, which gave more top end than I had ever had [up to about 7500], but now it was loading up in the low range [a bit like an over choked motor, it was un-mistakeable]. So then I twigged that the mains were way too small, the range was just wrong and no fiddling with the needles was going to fix it.

I put in 137.5's and set the needles one groove higher than standard and all of a sudden was pulling over 8000.
I tested full throttle in fourth, but as that gives something over 180 kph [I didn't want to spend a lot of time looking at the instruments], I've since decided that flat out in 3rd is adequate for testing purposes.

140 mains gave redline, something I'd never seen before and now with the needles just one groove higher than standard was getting even power from 3 k on.

This bike has no facility for insitu float level testing, so I found some brass fittings that have the same [after running a die over them] thread as the bowl plugs, and brazed a bit of copper tube onto them so that I could fit plastic tubes, and see what the levels were....two were just about flood level [which explained why it would die on bumping it off the centre stand] and two were sort of okay.

On lowering the level, a mild hesitation showed up just off idle.

Just to see what would happen, I've gone up to 145's....
it seems to run even better.....pull redline, and dare you to keep the throttle open, and to counter the hesitation [and the fact that to achieve best idle the mixture screws are between 1.5 and 2 turns out] I've gone up to 45 pilots.

Another change I made was to drill the air box and now with all the changes I have useful power from
3 k all the way to redline.

A side effect of drilling the box is a noticeable increase in induction noise at low revs and wide throttle settings [sometmes I wonder if it is the extra noise that makes me think there is more power low down, maybe Harley riders have something after all ]

Anyway, having made a short story long, I'm wondering if you have 'a light bog at 1/4 throttle', are you sure it wants more fuel.....or less? When you say 'light bog', is it like the motor is cold, or is it like the choke is on?
Cheers Badger