need help once again

i have an 83 xj550 and it has 4--2 exhaust,pod filters and larger jets(don't know what size.anyway i cleaned the carbs and reinstalled.now i can't get it to run without choke.i have the mix. screws out 2 turns and the plugs are dry and white after i run it.missing at mid throttle and no idle without choke.do i need to turn mix screws out more? was running fine until i put stp carb cleaner in the tank then it would bog down at full throttle.i actually had the throttle wide open just to get it home but it would only run at 1000-1500 rpm, that is why i cleaned the carbs.also cleaned tank and petcock.fuel flow is fine.new plugs.

 

Maybe the cleaner broke something loose and clogged a needle? Maybe it damaged some seals/rubber?

 

i pulled every possible jet and i mean every jet and made sure they were clean.light shining bright thru ervery one.emulsion tubes, mains etc.

 

Verify your fuel lines (front the tank to the carbs, and the vacum line) are in good shape, not clogged? Run it on PRI?

 

new fuel lines and filter. fuel flow arrow on filter is towards carbs also.i have a colortune.how do i use it if i can't get it to idle.can i adjust off idle?

 

On an 83 you should start the pilot screws at 3 turns.

Jets all go back in the right spots?

 

Re: jets going back where they belong

I seem to remember something about a manual showing the idle and pilot jets being swapped.

 

When you type "Won't run without choke" ...
That a Fuel Delivery issue clue.

You need to know what size Pilot Jets you are running.
Your Bike is running Mikuni's set-up for Airbox Main AIR Jetting.
You need larger Main AIR Jets for the Pods.
The Main FUEL Jet [allows] more FUEL to be metered for uptake.

Unless you INCREASE the amount of Main AIR -and- INCREASE the size of the Metering Ports in the Emulsion Tubes, to allow the Increased Flow of Main Air through the Emulsion Tubes -- to Pick-up and Deliver the Quantity of FUEL [allowed] by the Main Jet ...

The QUANTITY of FUEL drawn-up into the Intake Stream despite the SIZE of the Main FUEL Jet is insufficient for the VOLUME of Intake Air passing into the Cylinder because there isn't enough Main AIR Introduced through the Emulsion Tubes to:
1. Move to the Decreased Pressure and Manifold Vacuum's effect within the Venturi at the top of the Emulsion Tube to carry-up Fuel and break-up that Fuel which IS being drawn.
A VOLUME which is BOTH -- Lean and insufficiently atomized.

The Mixture is LEAN.
Not because the size of the Main Jet is too small.
But, because the Main AIR needed to help carry-up the Fuel isn't enough to carry the Volume needed.

The Volume that does get drawn-up through the Emulsion Tube remains in a Raw Fuel State. Getting sucked-out of the Emulsion Tube in more of a stream than a mist; because there wasn't enough Air bleeding-in from the surround of the Emulsion Tube to atomize the stream. What gets delivered into the Intake Stream arrives into the Combustion Chamber insufficiently mixed with the Air to provide an efficient and powerful burn.

Somebody with a lot of time and patience needs to fabricate an Emulsion Tube with a GRADUATED Set of Metering Ports larger than the Poorts that come drilled in it -- stock.

 

Yeah! What he said.

 

it ran great for 6-8 months on the same setup i descibed.i have not changed anything,jets etc. i just cleaned them inside and out. do i need to turn the mixture screws out more?

 

Are you sure the floats are in the right way, as in right side up ?

 

Re: need help once again/compression?

i have done a compression check with an automotive tester w/ colortune tip connected and i get cyl.1 is at 30 psi,2-35,3-25 and cylinder 4 is at 30.can i use an automotive tester for this or is there onf just for motorcycles. this is the bike i have polsted prior comments on.i now remember why i pulled the carbs after it ran bad, it happened all of a sudden,could it be head gasket?it will run on full choke and also connected colortune while i had mid throttle and tried to adjust air/fuel screws but no differnce in color all are lean with mix screws 5-6 turns out. can anyone help on this? :?

 

Cobra:

Those numbers are too low for the Bike to run.
Compression Check:
Fully Charged-up Battery
Good Battery -- Engine turns-over fast.
Pull ALL the Plugs
Wide Open Throttles during testing.
Conduct Test.

 

Wha tdo you mean Colortunr tip connected to compression tester ?? you should have over 100 psi for compression depending on the condition of the engine I dont think the engine will run at 30 psi

 

it seems that you have a lean condition, by turning the mix screws out, you are getting it leaner(am i wrong?), i will suggest try 1 1/2 turns out and see what happens, i had that problem with one of my motorcycles after i cleaned the carbs and by closing the screws it got better. hope this helps

 

First things first.

Let's all get on the same page with this Compression Check.
30 psi is way too low for the Engine to run at all.
Did the Compression Test get done right?

If the Compression Test shows numbers in the 30 psi area ... tuning Carbs it a moot point.
You have to correct the Compression Problem ... first!

I hope ... the Test was done wrong.
Plugs not pulled
Weak Battery
Throttles not open.

THAT might cause 30 ...
Usually causes 65 ~ 80, though.
30 psi ... OMG! ... THAT'S Really very bad.

 

i just did a wet comp check with throtle wide open and 1 is 40,2 is 50,3 is 35, and 4 is 55. i was tol screws in make it leaner and out make it richer.is that right? the colortune tip is for adapter on my automotive tester.

 

i don't understand though, it runs if you have choke on and i drove it down the road for a test and with the choke half open, it cruises down the road fine.i had all plugs pulled and throttle wide open when i tested it. may have to charge battery overnight. hope that helps. if i get the same readings tommorrow what should i expect> rings,head gasket ,motor?

 

ok did another wet comp check and 1 and 2 are at 45-50, 3 and 4 are at 110-115.battery is at full charge,throttle wide open and all plugs pulled.

 

You got a few way below bare minimum. You can't reasonably expect to fine-tune an engine to run on Compression that low.
With those numbers being as low as that; you're on the verge of throwing a rod.
With hardly any compression to slow the movement of the piston; there is a strain on the connecting rod.
After a bit ... it just lets loose because there no opposing force to keep the piston from heading straight-up through the top of the head.

You either need to do a load of work to bring-back compression.
Or ...
Swap that Motor out for one better than the one you got.

When you go Motor shopping ... Do a Compression Test before buying the replacement motor.