Rich mixture

[popres]

I have a 1979 XS 11 special, it did not run for several years, took it to the Yamaha dealer for repair and service. Work was expensive and not satisfactory. I have cleanded the carbs, set the floats at 25mm and set the needle jets in the fourth space. ( live at 4500' msl). Bike ideles good runs fine with plugs four heat ranges above normal but still fouls plugs with black carbon in about four miles. Syncronized carbs but the manafold vacume is at seven inches. Has anyone had this experience with the XS 11?

[fxrer]

Number ONE problem with these bikes?.......... Carburetors, mixture, sync, jets, etc. Must be HUNDREDS of threads on this subject. Do a "Search", left column, get some pop corn, and be ready to enjoy hours of reading on the topic!

[Do Lee]

What size are your jets? Do you have stock exhaust or aftermarket pipes? Do you have the stock filter and filter box or aftermarket filter in stock filter box or do you have filter pods? Did the service tech. do a carb clean or carb spray while the bike was running? Location also plays a part in how well your bike runs.

Needle clip location is 3rd slot, you said 4th slot 4th from top or 4th from bottom.

I also have a 79 XS1100SF with a Winning preformance 4 into 1 exhaust, K&N air filter in stock filter box, 145 mains and 45 pilots. stock is 137.5 mains and 42.5 pilots. I have drilled out the bottom of my air filter box (to the inside of the filter) to allow more air flow. Bike runs good with plenty of power throughout the bands (low-mid-high)

Back in the 1981 or 1982 when I put the header and changed out the jets, syncronized carbs and tuned each carb with the gas analyzer we had at the shop to get the CO% @ idle around 2.5 to 3% and when I reved it up the CO would drop to around 1 to .5%. This did take 99.9% of the sluggishness out of my bike. Now a days my bike is not as crisp as it once was but neither am I.

Every 4 stroke multi-cylinder motorcycle that was sold from or came for repairs to our shop would automatically be analyzed and tuned to the specs ran better and had an increase in fuel mileage.

[Winterhawk]

The Yamaha shop screwed up and used K+L jets I bet. Replace the pilot jets with OEM and it should be fine.

[popres]

Rich mixture

As far as I know the motorcycle is stock with the exception of a Kirker four into one exhaust system. Unless the dealer changed jets it ran fine when I bought the cycle. I parked it in the late 90's and with the cost of fuel thought it would be a good way to go to the office. The position of the clip was in the third or middle and i rasised it to next to the top or what I call the fourth position. The dealer shop did a spray clean, I disassembled the carbs and put them in a new solution of Berrymans carb cleaner for about eight hours. Re-assembled to specs in clymers and a Yamaha service manuel. The carbs do not run over any more as they did from the service shop. I was unable to remove all of the jets but ran proper size drills through all. It idles great at a constant speed, coming off slow idle has a slight hesitation and after about a mile it starts to struggle around 3 to 4 k rpm around 5k it come alive again but will completly foul plugs in a short distance less than ten miles ever hotter plugs. Number four cylender seems to be running correct and I believe it has a new float in it that was installed at the service shop. Hope all are fairing well from the Hurricane.

[Winterhawk]

Use an easy out and remove your pilot jets and replace them. I think the drill size was wrong.

The EGA machines used to be nice to use but these days they are so old and the lines are crap. Calibration is off also. I tried to get the one I used going and it looks like an expensive hassle.

[popres]

Rich misture

Did not drill jets just made sure the passages were all clean. I have never had any luck on drilling jets even in lathe.

[TopCatGr58]

Hey Popres,

Hate to tell you this, but spinning drill bits inside the main opening of the jets didn't do much for your carbs. Take a look at the tech tips for carbs and look closely at the pictures of the pilot jets and emulsion tubes! There are many small ports in the sides of the jets and tubes that are involved in metering the fuel and air mixtures together. When carbs sit, the gas gets all varnished and gummed up and clogs all of these fine ports.

YOU HAVE TO TAKE THEM THOROUGHLY APART to properly clean the jets to get them to function properly. Secondly, if you put the entire carb bodies in Berryman's, then you have probably ruined the throttle shaft seals, and have vacuum leaks around the shafts.

You said you took the carbs apart, but just how far apart did you take them? Did you remove the emulsion tubes thru the top of the carbs after removing the main jets from the bottom?

Folks have posted great success with reverse direction drill bits to get the pilot jets out!? Still sounds like most of your problems are in the carbs! Good luck!
T.C.

[popres]

Rich mixture

The drill bits were just used a probe not in a drill motor. The pilot, main jet and main nozzels were all removed and inspected with all of the passages clear. The carbrs were completly disassmebled before they were dipped into the carb solvent. I have a lot of experience on automotive and aircraft carbs and do understand the need for doing it right. Thanks for the info, it appears the problem is going to be floats or the air fuel mixture adjustment. Cycle really runs good when the plugs are clean and does not produce the odor of rich mixture out of the exhaust.

Thanks!

[Winterhawk]

I still have a feeling that the pilot jets might not be OEM.

If the compression is ok then do a fuel LEVEL check on all four carbs.

Not sure but the level should be slightly under the float bowl gasket surface? Somebody correct this if I'm wrong.
TopCat?, Ken?


I think that some carb manufacturers's jet sizes doesn't match the drill sizes.

Braden from Merriam Cycle / XS Eleven Heaven told me this one time

[DiverRay]

popres;
You may also want to try setting the floats level at 24mm. I've noticed on my bike it seems to run cleaner with the level slightly below the "factory" setting. I think it has something to do with age and wear on the needle and seat. it does seem as if your getting too much fuel into the carb bowels. The other check is to be sure you don't have fuel inside the floats. I know you probably checked, but if you have the "tin" floats, you may have pin holes in the floats the shop didn't replace!
Ray

[TopCatGr58]

Hey Popres/Bill,

No aspersions on your knowledge base was ever intended! Apologies if what I said came across as such! You really shouldn't have to be running 4 heat ranges HOTTER than stock! Also, being at almost a mile above sea level, you need to be running a bit leaner jets than stock as well! As has been recommended, try setting the floats lower/leaner. Also, what size are the mains? Also, did your carbs have the pilot jet caps? Some are rubber, some are metal cap screws. IF they weren't there or left off, it can cause much richer mixture....more affecting the pilot circuit than the mains, but the pilot contributes well into the mid range of rpms, and could still cause rich problems? The pilots are supposed to feed thru a common port in the main jet tower, and NOT DIRECTLY thru the bowl...hence the caps!

Are you sure that there's no restriction of air flow thru the airbox, snorkel!? It's amazing how much the floats settings contribute to the richness. And, yes it's a good idea to put the floats into almost boiling water and check for leaks....air bubbles escaping!

Hang in there and keep at it, you'll get it right soon!
T.C.

[popres]

Rich mixture

Carb has pilot jet caps of the threaded variety with a copper warsher. I am begenning to think it is a combination of pilot jet screw adjustment and float level. I have the float levels set at 26 mm with my own home made tool. The carbs gasket face is recessed and if my memory serves me I set it in the bottom of the recess. When I got the bike back from the shop it had new needles and seats and set at 22 mm and gasoling ran over into the air box. I have tried it with the bottom of the air cleaner loose and it is a new yamaha air filter. All indicators that I have and with my limited amount of knowledge on CV carbs limited to older SU on Volvo's this is going to likely be the solution. Will spend a couple of hours as soon as time permits and give it another try. I am running 4 ranges hotter as that is what I have in stock and have to go two hundred miles to get new plugs.
I must say this is one of the best forums that I have seen you peoplel are great.

Thanks

Bill

[TopCatGr58]

Hey Bill,

That must be one heck of a large ranch!! Well, when you go back into the carbs, double check the size of the mains, stock were 137.5. You may want to try a couple of sizes lower due to your altitude? Yeah, some folks have set the floats 1 or more mm lower than stock settings to reduce a rich condition!

BTW, have you checked the oil for signs of gas contamination? Since you had it coming out the airbox, it could have gotten into the intake, and if the intake valve was open, then it could have gotten in and down past the rings. Put a stick into the oil thru the filler opening, and then try to light it. IF it lights, you've got gas in the oil, need to change it immediately, so you won't burn your bearings out. Thinned out oil can also aggravate things in the top end. Glad you found us, and hope to continue to help you where we can.

Hope to hear a "solved" report before too long!
T.C.

[popres]

Rich Mixture

Ranch not that large for her but
13,000 acres and a hunt program, aging mother and a gun shop keeps a guy off the streets. Will check the oil, but level did not change but does not take much gas to dillute, actually have a crawler that has a system to put diesel into the crankcase for winter operation. Don't need it here.

Thanks

Bill