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needles all the way up, still getting white plugs...

  • Thread starter Thread starter gsBert
  • Start date Start date
G

gsBert

Guest
hi, me again.

so i have my needles all the way up (clip in lowest position of 5)
im still getting white plugs, ie: runnign lean.
this is after a plug chop from runnign 10 seconds at 1/2 throttle.

its a 1150 engine (stock) with 36mm slingshot carbs (semi flatslide CV)

my main is a 140.

screws are 2 turns out

nice light tan on the flosed throttle up to 1/8 chop though...

im thinking of removing the main jets to see if thats my restriction...
im also thinking maybe my floats are too high, not filling the bowls enough. could that affect it?

i get a lot of gray smoke when on the choke and it stinks, but nothing when idling normally and i cant see any smoke when riding...
 
Bert -- You have been so helpful to me, I wish I wish I could help you now. :?

Scud
 
Slingshots

Slingshots

Im running 34's on a 750e w/142.5 mains. Thats what came with my jet kit & 137.5 for stage 1. I would go up on the mains. Try bringing your screws out to 3-4 turns. My bike was to lean on idle at 3 turns out. Went 4 problem solved.
 
screws are 2 turns out

nice light tan on the flosed throttle up to 1/8 chop though...
Click to expand...

Bert,

Try turning your mixture screws out 1/2 a turn or even a full turn and maybe go up a couple of sizes on the main. Light tan sounds lean on the pilot and the needles can't flow enough to cover for that. The bigger mains may help, as well, as you are getting to the overlap area between the needles and mains at 1/2 throttle. If your plugs are white, you need to add some fuel, pronto!


Mark
 
I have the same carbs on my 1150 (1990 GSXR 36mm). I'm running 147.5 mains. Needles are fourth clip from top, pilots 32 up from stock 30. 2.5 on the air/fuel with K&N pods. The floats had to be leaned out from a suggested 14mm starting point to 17-18mm. The motor has MTC 1229 piston kit, and Falicon super crank , otherwise it's stock. It does have Pingel petcock. Maybe that could be an issue with pods if you're running a stock petcock. Not enough fuel getting through.

The jet kit is an old Dynojet with super blunt needles, don't know if they all look like that. I have a Factory jet kit as well for this carb and the needles look totally different, tapered to a point.
But they didn't work in the used carbs I bought. Fouled dozens of plugs.

Also the slides had nylon hex plugs in the bottom with holes inside. I recall you mentioning having one blocked off. Both of mine are open per carb.

I don't know if this is a factor, but the GSXR carbs sit about 10-15 degrees at an angle to the intake manifold in stock form.

I had to fabricate some crude support to hold the carbs up, not at that angle, but somewhat level. I blew two or three carb boots off before I supported them. Back pressure I guess.
 
My problem was the opposite with needles. Plugs kept fouling with the dynojet needles switched to factory jet kit needles and the bike ran much better. Dyno jet needles had more aggresive taper. I also switched to the pingel petcock which was a good investment.
 
The Dynojet's I have almost have no taper. They almost seem to taper part way down the needle then widen a hair at the bottom. I bought used with kit installed and have no idea if the needles were tinkered with.

Sounds like maybe they were or there is an older version compared to what you have. What mains are you running and needle position?
 
Wow! You got a few bikes. Running 142.5 mains, needle @ 4 clip from top. The carbs are 86 gsxr 1100 (34mm). 4 turns out on screws. K&N filters V&H 4into1.



82 GS 750E
 
well, i ran without main jets and got black plugs...

guess my restriction was at the mains.

i ordered a bunch of jets: 147.5 (which i think will work) 150, 152.5 and 155.

im gonna put my needles back to the middle position out of five to see where i stand with the bigger mains will start with the 147.5...

please leave me alone with the mixture screws, it doesnt affect half throttle operation, and "nice light tan" is where i want them at that throttle opening (1 eigth), no load on the engine and less fuel consumption. im at 2 turns out and my pilots are 36.5... all good up to 1/4 throttle where i start runnign lean (needle circuit)

i'll post my results if it doesnt start snowing before i get the jets...

i'll expect to be runnign a bit lean because of the low temperature and i dont know if my slide holes are the right size, though the slides seem to nicely follow the butterfly...
 
well, i ran without main jets and got black plugs...
Click to expand...

That's a good sign... At least you know it was the mains that were affecting the 1/2 throttle chop.

please leave me alone with the mixture screws, it doesnt affect half throttle operation, and "nice light tan" is where i want them at that throttle opening (1 eigth), no load on the engine and less fuel consumption. im at 2 turns out and my pilots are 36.5... all good up to 1/4 throttle where i start runnign lean (needle circuit)
Click to expand...

I don't really have an issue with being a touch lean on the pilot, it doesn't hurt the motor and helps mileage, as you say. But the pilot setting certainly does affect the mixture all the way up. I was suggesting that richening up the pilot mix may help bridge the jump onto the needles because they were looking lean. Since you say the mains were the culprit, I would leave the pilot circuit alone and fatten up the mains as you are doing. Then you can tweak the pilot circuit if necessary to smooth things out after you are in the ballpark with everything else.


Mark
 
yeah mark, you're right, lol.

when i had the needle clip in the middle groove, all was smooth, albeit too lean.
so i dont think ill have to adjust the mixture screw, especially since its only mixing fuel on closed throttle on my bike/carbs. the pilot jet is pretty big so it flows plenty. lean across the board was the mains. but if after installign the proper size mains (if i ever get them before snow falls) i find some rough spots, ill do very precise plug chops (closed, 1/16, 1/8, 1/4, 1/2) and see which circuit needs tweaking
 
Hoomgar said:
Bert, are you using a jet kit or stock needles?
Click to expand...

Bert, I wont jump in as I see your getting plenty help already but I was curious about this and you didn't answer. Maybe you gave that info elsewhere and I missed it?
 
i wish i knew if they were stock needles or a kit...

lol, they are mikuni parts, single taper and match teh emulsion tubes...

the carb bodies are off a bike, the emulsion tubes and needles off another.

the needles i had in there when i got the carbs were worn and had a double taper... but now i have a single taper on them and found soem emulsion tubes that dotn let a ton of fuel flow past the needle...
 
well, i jsut diod a 1/2 throttle chop with the 147.5 jets.

still running lean...

the needles are still all the way up.

by the way, the plug is black but the electrodes are white (bordering on light tan so i think im getting close).

am i correct in only caring about the electrode colour?
(im chopping the engine off after accelerating at 1/2 throttle for 10 seconds in fifth gear on a level road)

next im gonna jump way richer on the mains and try the 155s...

if i start running rich (i sure hope i do) ill lower the needles till that circuit is fine then try a plugchop at wot and if im rich on the main, ill decrease to a 152.5 and retest...

my idle is still giving me light tan electrodes.
 
With a stock intake and exhaust, the jet needles shouldn't need to be raised to their richest position. This unusual adjustment tells me you're trying to force the carbs to work. It may work out for you, but it sounds like compensation jetting to me.
I'm not sure of all your adjustments, but the jetting starts with correct float levels. The primary air jets may be too large too in addition to not knowing what the correct needle jet size is and what jet needle works best with that size needle jet.
And what jetting circuit are you testing for at 1/2 throttle?
 
And another little check to help determine main jet size...with the bike in top gear and going about 60 mph, roll on the throttle fully. Be sure the bike is well in its powerband and on the cam, should only take a couple seconds. Now back off the throttle about 1/6 turn. If it actually pulls harder, you're lean on the main jet.
If the performance becomes ragged/sluggish, you're rich on the main jet.
As with any test/check, this assumes the motor is in otherwise good tune.
 
keith: maybe i should repost my bike's specs in every single post to make sure...

it hasnt got a stock intake or exhaust or even carbs...
i use dual k&n and a 4:1 that isnt straight through.

the carbs dont have an air screw but a fuel screw, they're bs36ss slingshot semiflatslide of unknown origin, with unknown needles.

at 1/2 throttle, im testing the needle circuit, that should be obvious.
the reason im talkiing about mains is originally, i was runnign lean on the needle circuit, even with them all the way up. (havent tried full throttle yet). when i removed my main jets to try without them i discovered that i started runnign rich so im guessign the mains were restricting my needles too much.

the only circuit that's working right (light tan plugs) is the pilot, but i think my pilot jet might be too large, the bike smokes a lot with the choke on, grey smoke, dissapears with the choke off....

so im gonna put the 155s in and try a 1/2 throttle chop. ill swap plug #4 for a new one so i can get a good read. dont want to swap all 4 since i only have 4 on hand and will likely need about 3-4 sets of them before this sucker is jetted right....
im hoping the plug will come out rich. at which point ill lower the needles to the center groove and re-test. if theyre fine, ill try some full throttle chops to determine if and by how much i must shrink my main...

thanks for the full throttle test idea, its gonan be easier than running 10 seconds at wot and runnign out of road/balls/demerit points.

once i have a ballpark, ill buy some dyno time to fine tune for all rpm ranges, throttle openings and loads...
 
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