Hi float level = lean idle mix?

[macnut xj]

Well, in my ongoing battle to fix the low-end problems on eXJunk, I did the "carb shimmy" last night and pulled them back off. Before beginning the tear-down (again!), I decided to build Ken's carb stand. When I got it done, I mounted my temporary tank, set the carbs on it, and checked the float level before doing anything. I found that I had the float level about 1/8" too high on all the carbs. It would seem that would cause a rich problem, but what I had was a lean low speed condition. I had to have the pilot screws backed out about 4.5 to 5 turns to get it to idle and accelerate (with a bad stumble). I still had to choke it to get it accelerate until it hit about 5k. Then it ran like a scalded dog! I'm assuming that opening the pilot screws richens the mix. And even after I disassembled the carbs, I found nothing obviously wrong. I did put all the jets and the needle tubes into the soak overnight. Probably this evening I wil go thru all the parts and the carb bodies with spray cleaner and compressed air and clean everything up and reassemble. Then I'll use the stand to bench synch and set the float levels properly. The deeper I get into this, the more baffled I am..... Is there anyplace that shows a cutaway with all the circuits for these carbs?

[piet]

what about the condition of your airfilter ?is there foam on one side to prevent leaking air there and there must be a peace of foamfilter at the bottom of the airfilterbox,and what kind of exhaust do you got on the bike

[piet]

you can compare a good carb (check color bougie) with a bad one and see if there is dirt inside the fine holes by keeping them both upside down and drip in some fuel in the idle intake pipe's ,if there is a difference in going down the drainholes you have to clean the fine holes again.

[macnut xj]

It has the stock exhaust. I've tried it without the air filter in the housing, and there was no difference. The XJ has a whole different airbox/filter than the XS. XJ doesn't have foam on it, other than a thin sealing strip around the edges where it meets the bottom inside of the airbox. It uses a pleated paper filter like a car. Anyway, I would expect if there was a problem in the airbox it would be more likely to run rich. The plugs all show white (lean). I have all the jets and tubes soaking right now, and I will be going over everything with a microscope (figuratively speaking, of course) when I start to reassemble. I just wish I had something which showed all the passages inside the carb. It would really help in making sure all the passages are open.

[John]

Carb cut away view

http://www.carbparts.com/mikuni/mikuni_tuning_info.htm
http://www.carbparts.com/mikuni/miku...uning_info.htm
Try looking here.

[John]

Try this one also

http://home.earthlink.net/~sidskids/carbs/carbs.gif


Hey John, thanks, I editted your post to show the picture outright. I remember seeing this but couldn't remember where? I've saved it and will be adding it to the photos archive on XS11.com's images for tech tips files! T.C.

[skids]

You might try going to a bigger number pilot jet. The pilot screw can only do so much to help out. The pilot screw hole and the other three pinholes (Micuni) near the throttle plate all draw fuel from the pilot jet. Dennis Kirk has #45's in the six bleed hole configuration (1+2+1+2). If you have an XJ, I have no idea what number you would need.

[macnut xj]

Yep, XJ. The pilot jets in this only have the thru hole. No cross holes. After letting the jets and emulsion tubes soak for a day, I went thru all these pieces tonight with compressed air and a fine stiff wire. I even shined a strong light thru all the openings to be sure it's all clean. Everything is spotless now! If I still have a problem, it's going to have to be inside the carb bodies. That's on tap for tomorrow. I printed out a copy of the pic of the passages, and I will use that and the piece of wire, some carb cleaner and the air to be sure I get all the passages clean. Once that's all done, I'll set the float levels, do the bench sync, and we'll see what happens. If this don't do it, I'm giving up! Could be another XJ for sale........

[steelcat]

I would also check the jets. Are they the right size? Did someone put in a K&L kit?

[piet]

if you buy xjr carbs the power increases to 108 hp and the fuel consumption goes down,i found this german article on a site




Tipps und TrickXS

1.0) zur Verbrauchsreduzierung rate ich zum Einbau des Vergasers der XJR1200/1300.

2.0) Der Einbau des XJR Vergasers ist recht einfach (?). Der am "XJR Vergaser" befindliche "Drosselklappensensor" wird einfach nicht angeschlossen.

3.0) Die Chokemechanik wird vom XS auf den XJR Vergaser umgeschraubt, passt 100%, da beide von Mikuni sind.

An einem der "4 XJR Vergaser" muß ein Röhrchen, so wie beim orig. XS Vergaser eingesetzt werden. Eine 6mm Schraube nehmen und ein 1mm Loch reinbohren.

Der orig. XS Gaszug muß durch einen Schraubnippel angepasst werden.

Orig. XS Ansaugstutzen und die Öffnungen des Luftfilterkastens passen zu 100%.

Die Hauptdüsen werden vom original Vergaser übernommen. Nach diesem Umbau ist die Leistungsentfaltung über das gesamte Drehzahlband einfach nur beeindruckend,der Drehmoment gewaltig.

Die Motorleistung beträgt dann 108 PS auf dem Prüfstand. Der Benzinverbrauch liegt nun bei 5,5 - max 7,5 Liter !!!

Einmal im Jahr Inspektion (Öl/-u. Filterwechsel, Kardan abschmieren, Reifenwechsel, Bremsflüssigkeit wechseln)


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