Stupid choke circuit (maybe idle circuit)

[latheboy]

Something is up with the choke circuit on the shitfighter.

When I run it on the side stand with the choke ON then stand it up the rev’s die.

When it’s on the side stand with NO choke and stand it up it’s fine.

Fuel pump is running all the time so it's not that.
Standard pilot jets, air screws are 2 1/5 turns out.
Everything appears to be working ie: the plungers are all moving with together.

Does anyone have an idea of whats going on or had this before?

[ozzy1100]

Can you keep it alive when revs drop or no mater what it dies ?

[latheboy]

If i give it a rev as i stand it up it'll keep running but still stumbles a bit.

[xa-mont]

sounds like it's fucked mate.

I'll have to take it off your hands i guess.

Ahhhh well....

[latheboy]

Yeah ok Trav i guess your right.

At smoko i put a AFR meter on it.

Started with the choke on and on the side stand, when I stood it up it died in revs.
Tried it again giving it a rev as I stood it up and no problem.
After that it was fine standing it up without a rev, it may have warmed up enough by now that it wasn’t a problem.

Idle on choke is 10.6:1 to 11.1 :1
Idle off choke is 15.0ish:1 up to 17:1 is varies a bit and it does sneeze a little.
It runs good just a little sneeze every now and again.

Too lean on the pilot is the word on the street...

[Hillsy]

Maybe bump up the fuel level in a the bowls a mm or two.....

[ozzy1100]

sorry hillsy float hight changes mains but fuck all on the pilot from mem
or if it did means changeing mains as well and if he has that right dont want to fuck with it
i think for every mm or is it 1/2 mm is one main jet size fuck its been awhile lol

[latheboy]

The float level was dropped because of fuel pressure. Its turbo'ed now.
I was told it might help to lift it up a bit, i need to read up on how the carb works a bit more.

[ozzy1100]

Fuck I'll pull my head in lol sorry boys

[latheboy]

Don't be sorry, i asked because i wanted lots of different opinions.

[Hillsy]

I'm thinking if the bike is affected by picking it up off the side stand then it might be the fuel level in the bowls is a tad low and it is starving for fuel when it gets moved around.

Costs nothing to adjust - just a bit of time (assuming you don't break anything taking the carbs off.....)

[latheboy]

That is the plan Hillsy, just got to make time to pull it all off.
If only i didnt have all this extra stuff hanging off it...

[ozzy1100]

Just sux it changes so much of the tune
But not end of the world just the same as a needle
Hight change I quess and thinking about it it makes the
most seance, makes me remember how long it took to
chase a tune on my shit box and that wasn't turbo lol
Mind u I had a dyno bloke in my pocket at the time much easir
he did have a carb turbo bike go thro the shop back then ,blow my mind we
ended up smaller jets and softer tune than na. Shop shut down
before I got to see the finish tune( funny story packing up a tuck of this blokes shop
Because he went under and he turns to me and says fuck what will wife say when I get home
lol he hadn't told his miss's. Hunny I'm home btw we have no more shop)

[stiffsimon]

Just a thought but have you changed anything before this started happening? Maybe track backwards and try and identify something that you've done prior to this issue. Failing that I'd be inclined to strip and clean carbs, check wiring loom, fuel lines/filter, etc.Just a thought. By the way I've just invested in an ultrasonic cleaner so if you want anytrhing cleaning just give me a call/email.

[latheboy]

Where do i start Simon haha.

It was fine when i took it off the dyno so i think i've got some shit fuel that has made the problem obvious.

I might take you up on the offer too thanks.
Clean carb's, change float height and back on the dyno.

[Dynomutt]

How much did you drop the fuel level by? you only really need to drop 1mm or so. You are wayy too lean at idle, you should be shooting for 13 to 1 at idle, and an A/F of 12 to 1 when it boosts. What carbs are you using and what are your jet sizes and needle settings and float heights. It sounds like the fuel level has been dropped too far, when the bike is on its stand the fuel level to the left of the carb is higher which should be where the pilot jet is located, when you stand the bike up the fuel level is dropping relative to the pilot jet which is helping cause the lean condition.

[latheboy]

On OSS people say to drop the float 1mm for every PSI of fuel pressure, so i dropped it 3mm. It's going to come back up.
Jets are from left to right 125,125,117.5,117.5
Needles are Left to right 1down,1down,2down,3down from the top.
Jetting and needles are stagered and tuned to exhaust temps and AFR. Temps are within 25°c always.
Looking at the plugs after a plug cut shows no det or lean sign.

AFR is 11.7:1 to 12.2:1 on boost and WOT.
At 60kph cruise its 13.6:1
At 70kph cruise its 13.7:1 These 3 are 0psi to 0.5psi
At 80kph cruise its 14.0:1

I'm aiming for as lean as it will idle while running nice, somewhere in the 14's is nice. As soon as it revs the AFR richens up.