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.

 

There's an '82 Seca 550 motor on eBay right now for $150-$175. The bike had only 9885 miles on it (I bought other stuff like the instruments) and got parted out because the frame got broken. The guy's in PA.

 

should i re-ring the engine and what does the re-ring kit go for.have any web sites in mind?

 

I would think as Rick said you have a load of work to get it back in shape. You will really need to tear it down to figure out all what needs to be done.

Of course if you tear it down you should plan on all new gaskets and honing the head. You can't buy rings until you know how much honing or machining you head needs. You should also plan on doing the starter clutch while in there. I'm sure there are several other must dos but you get the point.

 

I'd save the rebuilding money and labor and buy the used engine.

 

thanks for all the help. i'll look into a used engine. any thoughts on where to go in south caroilna?

 

Cobra,

According to what you wrote about your bike which was running fine until you cleaned out the carbs, the white plugs and the results of the last compression test with the low result only on cylinders 1 and 2, I would suggest you to check out the head gasket. To me it looks like you have a leak in the head gasket between cylinder 1 and 2.

 

The Compression is Low ... across the board, though.

 

try the compression test with the other spark plugs installed. the compression in the cylinders helps it turn over. dumping compression out of the other cylinders will cause the cranking rpms to lower while you are on the compression stroke of the cylinder being tested. just try it, it may bring your numbers back to where they should be.

to test out Reins theory of the blown head gasket, wich is plausible:

remove the cams (makes all valves closed) and spark plugs. pressurize each cylinder with a rubber tipped blowgun through the plug hole. it should not leak out anywhere. if you blow into #1 and it blows back out of #2 plug hole, there is a head gasket leak. if you pressurize a cylinder and it blows out the exhaust or intake there is a valve issue. if it come sout the crankcase the piston could be cracked, have a hole in it, or the rings/cylinder could be wasted.

 

it's weird though.when i first start it up with full choke it runs fine.throttles up like a scalded dog! doesn't skip a beat. i can rev it up and down like it was brand new. how could it be the rings or head gasket? i can run it with half choke and it still runs like a scalded dog. only when i cut the choke off i have to give it full throttle just to keep it running at 2000 rpms. then i put full choke on and it revs back up to 2-3000 rpms and runs like a champ(besides the high rpms when choke is on).it runs so good on full choke the next door neighbor thinks i got a race car in my yard lol!

 

how do i find the size of my motor. is there a stamp on the block?i bought this bike about 2 years ago and tonight i find it is NOT a 1983 but on my frame it is 12/80 1980-81?and how do i tell if it is a seca or maxim? i feel so stupid right now!do i really have a 550? how do i tell? again feeling stupid!i had to appy for a lost title when i bought it and i was told it was a 1983 seca xj550.

 

Maybe your Compression Tester is out-of-whack???

Maybe the Values are ONE HUNDRED 30 - 35 ???

Take a Pic of the Face of that Gauge.
Lets see what the Scale is.

 

I did a compression test on mine with a brand new compression tester I bought at UAP about 5 years ago,(first time to use it) it read about 30psi across the board....hmmmm. shouldn't really be running........ so I used an old cheap one I had and what do you know 120 - 128 across the board.

Maybe try another tester??


And UAP wouldn't do anything for me....warrany was up about 4 years ago.

 

Chain drive?
Look for a stamp near one (not sure which) of the header pipes.

 

Yeah hold on a bit let's get this figured out logically.

First off, if it's chain-driven and a US model XJ it's a 550. In the US the only chain-drive XJs were 550s. Seca is the "sport" model, Maxim the "cruiser." The Seca has an 18" rear wheel; I believe the Max had a 16" or 17". The Seca has straight-spoked cast wheels, the Max has "swirly" spokes. Seca front brake is on the right fork, Max's front brake on the left.

Secondly: It wouldn't run as you described with compression that low, I too suspect a problem with your compression test. Your troubleshooting needs to progress logically, you can't begin to think of using a colortune which is a "fine-tuning" instrument on a machine that isn't running at least halfway right.

The fact that the bike seems to run fine, at least until it warms up, indicates you most likely DO have a carburetor issue, however: You said it "ran fine for 6-8 months" and "nothing changed" until you started messing with the carbs. One thing did change--the valves got tighter (they do that as they wear...) You aren't going to be able to solve this and get the bike running right until you take certain logical and necessary steps without omission:

1: Check (and adjust if necessary) your VALVE CLEARANCES. Very important, especially on the 550, to do this FIRST before trying to do any carb tuning. This may also explain some of your erratic compression test results, but let's hope not.

2: AFTER valve clearances in spec, do the compression test again, using a different tester.

3: Pull the rack o'carbs, re-check everything and BENCH SYNCH using a strip of business card (per RickCoMatic's "old school carb cleaning.") Make sure they pass the "clunk" test!

4: Make sure all boots are in place and all clamps and vacuum hoses tight and you didn't "trap" the throttle cable actuator under the fins when you reinstalled the carbs.

5: NOW you can pick up where we are right now, but until all of the above have been done, IN ORDER, you really aren't even sure what problem you're trying to solve, or one issue may be masking or contributing to another.

Give us some additional details on your bike, too, like maybe some pictures and how many miles are on it, etc.

 

i took the carbs back off and rechecked and every thing is clean and clear. took the mixture screws out and cleaned the tips and the orifices are clear,no trash.i have fine thread mixture screws and the screw heads are about to break,gonna get new mixture screws.how many turns out do i turn them,if there fine thread,still 3 ? or more? also how do i get a stripped one out? #2 i can't get out yet. one dumb question- can i do a compression test with the carbs off?

 

Sure why not....just like wide open throttle. The engine doesn't care about the carbs or exhaust it will compress or it won't.

 

How many miles on this bike?

 

THANK GOD!!

i got a new tester from snap-on and redid a compression check cold, it was 29 degrees this morning and what do you know- cyl.1- 100 psi,2- 140 psi,3- 150 psi and cyl 4 160 psi. i kept cranking until needle would not move anymore.i guess the problem all lies in the carbs! need to get new mixture screws recheck float levels. any help on how many turns out for fine thread mixture screws? i've got 140 main jets,does anyone know where to purchase a jet kit with this size in it?

 

Grrr...HOW MANY MILES ON THE BIKE??? Please check your valve clearances before you start beating your head against the wall, I suspect #1 may need immediate attention. VALVES BEFORE CARBS valves before carbs should be the XJ mantra... then please give us a little more info on your bike and we can get you zeroed right in. Chacal probably has the parts you need; PM 'chacal' or email info @ xj4ever (take spaces out of email address) but I'm serious: you simply cannot carb tune one of these motors if the valves need adjusting.

 

it's got 25,000 miles on it.had a pic but took it off my computer. i will first do the valve adjustment from my clymer manual while i'm trying to find a jet kit. thanks

 

Ahh, thank you. It may have never had a valve adjustment done and at that mileage it will need it. It will throw off any carb tuning you try to do. It's especially important on the 550s, honest.

 

I'd recheck the compression after doing the valves. I know the 650 spec is no more than 14 psi diff between cylinders. #1 looks pretty low even though it will run.

 

got a question on this. i found a rack of carbs from a 1982 seca with the factory plugs still over the mixture screws,and my scooter has got pod filters and free flow exhaust on it, if i install this rack of carbs(thourough cleaning before hand of course)do i have to adjust the mixture screws?and also if i change my main jets(#140) from the old carbs to the new carbs do i have to change the mixture? i know main jets only control top end but will this affect my idle/power output with factory jets(from the new carbs) having pod filters and free flow exhaust?

 

Q1: Yes. Q2: Yes. Q3: Yes. Even if you swapped that rack o'carbs from one completely stock 550 to another, they would need adjusting. Using a set of carbs from a stock motor with your setup will not only require rejetting but also re tuning. No way around it. But adjust your valves first.

+1 on getting yourself a spare rack o'carbs though. Nearly a necessity for serious XJ stewardship.

 

Cobra,

My Seca 550 developed the same syptoms you have (wouldn't idle without the choke applied). It's due to my throttle shaft seals (some call them butterfly shaft seals) leaking.

I'd suggest you start the bike and get it to where it's idling with the choke on. Then spray some carb cleaner around the shaft seals, if you're idle goes up, they leak.

Everyone else seems to be missing the point that it ran fine before you cleaned the carbs. Cleaning the carbs probably finished off the seals and they gave out due to age.

I think you just need to replace the throttle shaft seals and check your valve clearances.

 

i just got my new pilot screws(mixture screws) kit and i need to check my float drop with the bowls off, does anyone have a pic or spec for this?

 

ok the kit does not have the right parts in it, so does anyone know where i can get a set of JUST pilot mixture screws?(with springs and washer and o-rings?

 

chacal (PM info @ xj4ever.com) take the spaces around the "@" away. He has individual parts.