carburetors

[willinfish]

hi all, new to the group. This is my first post.
Just bought an 82 maxim xj1100 with 7,000 miles on it and I`m having carburetor problems. The carburetors that were on the bike had two T connectrs for the fuel and one straight connector connecting the #2 and #3 carburetor. Then also it also has two more T connectors connecting one and two and three and four. Which I don`t remember being hooked up to anything but I may be wrong. I bougth a set of carburetors off of ebay for an 82 xj1100 and they don`t have the upper T fittings and I can`t anything in the service manuel that shows these fittings. So which carburetors are right for this bike? Thank You in advance for any help.

Willinfish

[John]

The carbs that have the upper set of T fittings are from a 78-79 XS11. Yours should not have the upper set of T's. The T's are for the bowl vent on the older models. The XJ uses an orifice that is cast into the inlet of the throttle body/air horn. It will be at the 2 o'clock position on the XJ carbs, and will be absent from the older model ones. A question...do the carbs without the upper T fittings have two brackets that the carbs are attached to, and does the set with the upper T's only have one bracket attached to the carbs? Sounds like the ebay carbs are correct for an XJ11.

[willinfish]

Both sets of carburetors look identical. They both have the double brackets attached. The only difference is the T fittings.

Willinfish

[TopCatGr58]

Hey Willinfish,

Looks like the P.O. did a switcheroo on your carbs. He probably had some problems with them and got a set of 78-79 carbs and stuck them on there, hence, the extra "T" fittings between carbs.
Just surprising to hear about that with an XJ with allegedly onl 7K miles!?!? Depending on which set you use will determine which main jets should be in them. You go by the carb styles, not just the model of bike.

You'll want to take some time and read thru the tech tips and such to learn the differences between the carbs and such!

Good Luck!
T.C.

[John]

Another question

How is the choke applied on these carbs? The 78-79 carbs will have a lever on the left side, on #1 carb, and the proper XJ carbs will be activated by the cable from the left handlebar

[willinfish]

The choke is appplied by a cable on the left side of the handlebars on both sets.

[John]

Can you post a pic? We gotta see these...

[willinfish]

Here`s a front and back view of the carbuerators with arrows where the T fittings are and the connector tube between the #2 and #3 carbuerators

Willinfish

[John]

Next Question

In the bottom pic...it looks like the choke cable conects to the right side, or #4 carb. Is that correct? I parted out two XJ's recently, and I don't recall the carbs having the T fittings that yours have, and I thought the choke cable connected to the #1 carb, on the left. I could be wrong, it has been a while since I last saw the XJ carbs. Hopefully one of the XJ riders will jump in here.

[willinfish]

Carburetors

Yes, the choke connects to the #4 carburetor on the right side. The other thing I couldn`t find in the mauel was the connector pipe between carburetor #2 and 3. According to the Yamaha dealer the T fittings are no longer available and the straight pipe they have no idea on since it doesn`t show up on any of thier parts list.

Willinfish

[John]

Honestly, I don't think they are for an XJ1100. Can you find a part number anywhere? The XJ uses a Mikuni BS 34 II. Is there any chance these may be from some other model than an XJ1100? Can you measure the opening of the inlet side of the carbs? An XJ11 should be 53mm I believe. Did Yamaha make an XJ750?

[GNEPIG]

.. those carbs might be from something else, but the question is from what?. other than the early FJs that used that vacuum port i dont know what else.. that conector between carbs 2 and 3 is strange also.. suzuki used a carb set up real similar to ours also, this might be a set.. to many beers ago for me

[willinfish]

They are marked Mikuni on one side, made in Japan and measure about 53 millimeters on the inlet side.

[TopCatGr58]

That Dirty Rat P.O.!

Hey Willinfish,

You've got one bastardized set of carbs there, the P.O. really did a number on them and you!

Okay folks, those carbs are NOT from a 78-79 XS11, they are from the 80-81 series. I thought those inlet bells and the float bowls looked suspicious! Take a look at this picture of the 79 carbs I worked on for BasketCase:

You'll note that Mine have the required only 3 holes in the inlet bells and therefore needs the UPPER T's to vent the float bowls, whereas Fish's has 4....the bowls are vented thru the inlet bell, the upper "T's" are not needed, also note Fish's bowls have the side screw drain taps, Mine just the bottom hex head bolts!!

I hate to say it but Fish will probably need to take the carbs OFF the rack to figure this out! The newer style carbs STILL have the holes molded into the carb bodies, but they are plugged deep in the holes. The P.O. may have seen the holes and thought they needed the extra "T"s when they may not be needed at all! Same thing for the lower holes for the fuel inlets! He MAY have thought that those holes on the inside of carbs 2 and 3 needed to be connected, when they really don't!
Also note that Fish's pilot screws are the tall towers with the pilots screws recessed down deep into tower, not sticking up above the tower like on mine!

He/P.O. also swapped the XJ choke mechanism onto this set of carbs.
Here's the OEM choke setup with lever mechanism on the side of #1 carb!


Have fun taking them apart! Also you'll want to inspect what size Main Jets you have, and whether you have the small pilot jet/main jet tower tunnel, which will tell you whether you need to be using the rubber pilot jet plug or not, along with what size main jets to use, again depending on the presence or absence of this tower tunnel!!
T.C.

[LoserShoes]

Those sure look an awful lot like the carbs I'm rebuilding for my wifes XJ650J, except the choke valves are verticle not horizontal. I'll look when I go home tonight to see what the that middle connection is for.

Steve