Carsb 1 & 4 too rich

[davidsymons53]

My bike is a 1982 xj1100J. I bought in October and this is what the plugs look like after the first ride I had on it.




These are pics taken of the new plugs with 205 kms on them from the one ride.

The engine felt like it was a single cylinder. Thump, thump thump. The bike had no trouble doing 130 + KPH.It has a after market exhaust system with carbs 1 & 4 going to right muffler and carbs 2 & 3 going left. I spent a lot of time polishing the bluing from the headers only to have them blue in the same ride. The air intake is stock. I have not had the carbs off yet.

The PO sail he "spent a lot of money on the carbs last year", but did not know what was done. There were new rubber joints behind the carbs and the fuel lines were replaced. The left petcock was leaking and I replaced both.

Looking at the plugs, do you think I should go directly to the carbs first?

Could it be a weak coil on carbs 3 & 4 (weak spark)?

Or is there some other place I should be looking?

I have been reading the forums since October and you guys and gals really know your xs/xj's

David

[WMarshy]

Sound like you need to remove that exhaust imediately and hand it over to me. Sounds like a Jaradine spaghetti pipes. Plugs look rich all across the board, #4 being the worst. The other guys will chime in, you might be able to correct the F/A ratio by adjusting the screw. What plugs are you using BTW? If your taking the carbs off you might want to verify that they all have the same size jets and the needles are all at the same height.

[DGXSER]

Are you running the stock airbox or pod filters? Is this a 4-1 exhuast? Sounds like it is. What jets are in the carbs now?

All four look abit sooty to me. No 4 being the worst. Start with the above and we can work our way through this I would think.

[WMarshy]

...It has a after market exhaust system with carbs 1 & 4 going to right muffler and carbs 2 & 3 going left....

Sounds like a 4-2 to me. He said the PO had the carbs worked on but he personally has no idea what jetting is in them or what was done to them... Aside from pulling them off and finding out what jetting is in them, he could try making a F/A adjustment first. Definitely get a new set of plugs too.

[Guy_b_g]

Be sure to check your ignition also, the coils fire 1 & 4 and 2 & 3 respectively. So it could also be a weak ignition problem.

[davidsymons53]

Wmashy, I would love to find a stock exhaust system. The plugs are NGK BP6ES.

[cywelchjr]

Wmashy, I would love to find a stock exhaust system. The plugs are NGK BP6ES.

If the exhaust is the jardine spaghetti type you can probably find someone with stock pipes to trade with you as they are pretty rare and wanted. They pair the cylinders that work together on the same muffler together, there are some that say they are the best ones for the bike, and I have to say I like the sound they give it. They are called spaghetti pipes because they go under and over each other to get 2,3 and 1,4 paired on the same side.

[WMarshy]

Wmashy, I would love to find a stock exhaust system. The plugs are NGK BP6ES.

Dave,
Your plugs are the correct heat range, I think your just going to have to adjust F/A ratio to get it where you need it. Im at the same point as you are, time to break down and get the proper tools to do a carb sync and F/A adjustment. You should add the year and make/model of your bike into your signature in 'Edit profile' so we dont we dont ask a million times. Some info like carbs is specific to each model. I have a good set of original pipes off a 79 special I might consider trading but I dont know if they will fit the XJ. PM me and we can talk/swap pictures.

[davidsymons53]

Thanks for all the advice.

The bike is a 1982 xj1100j.

Air box and filter are stock.
The plugs are NGK BP6ES.
This is the exhaust system.








The coils are good.
I have used a can of seafoam split between two tanks of gas.

Next step, I will check idle mixture with my ColorTune.

Can I use the ColorTune to check mixture at any higher rpm?

Dave

[Fix]

Yep, look like jardine spaghetti pipes. Nice.

[Ivan]

I have the same pipes. they are nice. Mine have the shorter slash cut mufflers on them as opposed to yours with the longer ones.

If they blued again on the first ride, you are probably overly rich on all, causing the combustion to continue down to into the pipe. This would indicate VERY rich. But, usually pipes blue from being a bit lean.

The PO saying he had someone work on them is a good indicator that they are all jacked up. There are countless stories of so called professionals that don't know crap about carbs and customers loose scads of money and the bike runs worse than before. If for only that reason, I would pull the carbs and look for things to be in proper order. Check for proper jets, check that the enrichener circuits and plungers are working right, check that the bowl gaskets aren't covering any ports, check that the floats are set right, and check every thing else you can see. After you have done that, then its time to look into more "interesting" diagnostics. (Meaning we all throw out wild ass guesses until someone gets it right or you go insane...)

[WMarshy]

I know somewhere around here someone posted they put a set of super trap baffels on their 4-2...not sure if they were the OEM pipes or spaghetti pipes... The matter is, just throwing a set of OEM pipes on your bike isnt going to necessarly correct your rich condition. It's probly going to take some carb adjustments to get either set of pipes to run optimal.

[davidsymons53]

After much research and study I finally got the courage to remove the carbs from my XJ. Actually it was much easier than I thought it would be. I hope they go back on as easily.

The carb were extremely wet (soaked) with gas. This leads me to think the floats are too high. However the carbs were clean. The only thing dirty was the bottom of the float bowls. There was what appears to be a small collection of tiny rust flakes in the hollow at the drain screws. This was probably the result of the seafoam in the two tanks of gas I ran through the bike.

All the gas and air jets were open and unobstructed. The main jets were up - sized from 112.5 to 115. Everything else is stock. Should I go back to stock main jets?

Before I check the fuel level with the clear tube attached to the float bowl drain method (Fuel level: 3 +/-1 mm below from the carburetor mixing chamber body edge) I would like to make a preliminary float height adjustment.

I gleaned this information from the factory manual for the xs1100.

Float Adjustment (1978-1979)

4. Turn the carburetor assembly upside down.
5. Measure the distance from the bottom of the float to the float bowl gasket surface. The correct height is 1.012 ± 0.04 in. (25.7 ± I.O mm).
6. Adjust by carefully bending the tang on the float arm.

NOTE: Both floats in the same carburetor must be at the same height.

NOTE: The floats in all 4 carburetors must be adjusted to exactly the same height to maintain the same fuel/air mixture to all 4 cylinders.

7. If the float level is set too high, the result will be a rich fuel/air mixture. If it is set too low, the mixture will be too lean.


Float Adjustment (1980)
The float adjustment procedure is the same
as on previous models but the correct height is
changed to 0.906 +/·0.020 in. (23.0 +/- 0.5
mm).

Fuel Level Measurement (1981) (the clear tube method)
The bike must be exactly level for this
measurement to be accurate. Place pieces of
wood or shims under either side of the
centerstand or place a suitable size jack under
the engine and position the bike so that the
carburetor assembly is level from side to side.

My question is: what is the correct height measured from the bottom of the
float to the float bowl gasket surface for the xj1100? Would it be the same as the xs1100: 23.0 +/- 0.5 mm?

The float height (Measured the distance from the bottom of the float to the float bowl gasket surface) measurement on my XJ is 17.1 to 19.05 depending on the carb.

If the measurement is the same for both the XS and the XJ my floats are way to high causing a very rich mixture.

As always any advice will be appreciated.

David

[perurider]

I read that numbers 2 and 3 carbs are set up richer because theyre in the middle( richer=cooler), maybe the jets are switched, 1 and 4 have 2 and 3s jets in them, making them rich.

[petejw]

Hi David,
Those float heights are way to high, which will give
you your rich mixture, i havent got the xj, but im pretty sure the stock heights are the same for the later model xs carbs which are 23mm,
reset your float heights back to stock, thatll make a huge difference
to the way it will run, the stock jets are 110 but 115 should be ok
if you havent got the 110 to install.

while the carbs are off id check the size of the pilot jets
and do a bench sync.

once installed recheck your mixture screw settings and resync.

as some of the others have stated, all four plugs are rich.

if you do a search for the soda blaster, ive used it successfully
to clean up fouled plugs.