Finding 3rd carb body

[Oro]

Greetings! Happy to find this site. Long-term MC enthusiasts (dad raced Yamaha dirt bikes in the 70s; I've been riding since then and he's been riding since the late 50s).

A while ago, he got a very derelict 81 XS11 standard as a project; outdoors for a decade non-running and parts off, so... I have restored bikes myself, but haven't had my hand in this one until now. He's less inclined to go out posting questions (that old school) so I'm butting in.

It's coming together but he hit a carb problem. He had rebuilt the rack, but the 4th bowl was overflowing. I took it apart to give a 2nd pair of eyes and noticed the 4th float was slightly differently constructed than 1-3. Immediately I weighed them I could tell by hand they were very different), and 1-3 were within +/- 0.01g of each other, 4th was 1.8g heavier and not activating the same. The bike has a 4-1, and some digging makes me think it actually has E carbs from a 79 (which makes sense with a header - it had to be re-jetted somehow). I think the replacement float (the overweight brass one) was a correct 81 model, but it has 79 carbs on it (he said they were marked "E" - I didn't see the marks myself but didn't know where to look).

a) Can someone verify the brass floats in the pic are correct for a 78/79 bike, and should weight the same to crazy degrees of accuracy? I read somewhere 80/81 had plastic floats? The three floats on the left are identical and within +/- 0.01g, the two on the right are build differently and 10.6 and 10.8g vs 8.97g like the others. He bought a replacement float off ebay; I think the carbs came with one mis-matched float, and he bought a 2nd mis-matched float.

b) The 3rd carb is a b-t of a problem; the pilot screw was forced in so badly the tip broke, and the orifice area is pitted. (the bike was outside in WET western WA area a long time). Replacing that body would be good, I think, But I'm unsure how to make sure I get a compatible body for the 3rd carb and how they relate to possible take-offs from the 1-2 arrangement on an XS650.

Thanks for any advice!

[DiverRay]

I'd need a picture of the carbs to know what the bodies are. As far as #4, try to make sure the vent is clear, and that the float closes the needle valve. What I do is put the carbs without the bowls on upside down in a vice. put a temp fuel tank on the 3/4 carbs, and verify there is no leaking. Once you know everything is good, get back and we can go to the next part of the problem.

[SFerinTEXAS]

On a side note the brass floats had a tendency to leak ( take on gas ) . Try shaking them to see if you hear anything inside .

[cajun31]

Yamaha XS1100 Carburetor body #3 Fits 1978-1979 | eBay This is the one you are probably looking for. To be sure you need to post pictures of the carbs so they can be identified. The brass floats are why I think the listing I posted is what you need. However, folks over time change out parts so the pictures will allow us to see what you are dealing with.

[Oro]

Thanks for the quick responses. I meant to include pics to id the bodies for certain. Here are some. From what I found on this sheet last night:

http://clubs.hemmings.com/xs11/carbspec.htm


They are '78 carbs (I think); the bike build date is 3/81. The jets originally in the carbs matched the specs above for '78. The "E" stampings are on the float bowl boss (if that is what it really means). Also, the pilot screws are clearly adjustable, and not fixed.

[cajun31]

the Ebay listing I provided is the carb you want. It will work with the pictured bank of carbs. I question the year of the bike. What is the vin number? with the solid rotors pictured on the bike indicates it is either a 78 or 79. 81 for sure had slotted rotors. By the way ... introduce your dad to this site. Many of us are about his vintage.

[cajun31]

by the way these are the carbs that were on the 81 xs standard. Yamaha XS1100 XJ1100 Mikuni Carburetor Carb Set Bank 3J6 00 B093OEM | eBay

[Oro]

The bike didn't have front brakes on it when acquired. So the front brakes on it may not ID the year. We/he was going on the year based on this and the title:



But perhaps that's not definitive since an MSO can be different than year of manufacture.

BTW, I was wrong and we need the #2 body, not #3.

[DaveT]

Former Yamaha dealer here. That frame is a 1981 XJR1200SP model, not an XS11. My question: is the engine number the same as the frame number? If not, post the engine number to determine the year and model the engine is from.

[DiverRay]

As a side note, I see a lot of new parts on the carbs. They MUST BE Mikuni parts, or you will never get it to run properly. Most of us have spend countless hours trying to tune carbs with K&L parts/jets. Carbs that won't work correctly all of a sudden work great with the correct jets, seat, and needle valve in them.
Check the frame neck on the other side of that sticker. The frame VIN will be stamped into the steel. Let us know if it matches the sticker.

[JohnKa]

This is JohnKa. Father to Oro who is posting on my XS1100. Happy to answer any questions for those of you so willing to help. This bike was given to me if I would just haul it away. I love projects like this. I just finished a ‘81 Honda CB400T that came in a basket. Idles great but won’t pull it self because of a bad stator and I can’t find replacement part. Trying to upload photo, but having a problem

[FJ111200]

Former Yamaha dealer here. That frame is a 1981 XJR1200SP model, not an XS11. My question: is the engine number the same as the frame number? If not, post the engine number to determine the year and model the engine is from.

4R0 is a 1981 XS1100SH model. I've got a XJR and the first models were 1995 starting 4PU.

[DaveT]

4R0 is a 1981 XS1100SH model. I've got a XJR and the first models were 1995 starting 4PU.

Thanks for correction. The Yamaha VIN decoder led me down the wrong path.

[motoman]

Oro, the motor in that frame pictured is either a 78,79 or 80 model. The engine model lettering/numbering is stamped into top of case on the clutch side(right) above oil filler plug. Coding will start with a 2H7(IIRC). If motor were original, the motor coding would match the frame coding.

[cajun31]

Oro and JohnKA ... first and foremost ... welcome to the site. Two things that need to be clarified. As DiverRay and Motoman have stated ... the vin will be stamped into the frame neck as well as on the motor. Verify that number or numbers. That will definitively identify everything. The carburetors that are pictured are the ones that were on the bike or did you source the pictures from somewhere else? You stated the brakes and rotors were not original... do you still have the originals? What is is sounding like is you have a bike with a mix of parts from different years. We call them Frankenbikes. Not the end of the world mind you. It can still be made road worthy... it is just that you need to know for sure what you have so that the answers we give are correct. Tuning the carbs.. jetting etc...is different from the early years to the later years. One thing for sure ... you have arrived at the right site to get the help that you want. The vendor that I sent you the listing for the number 3 carb also has the number 2 as well as the number 1. He/she wants 41.00 dollars for each. Oro you mentioned that the pilot screws are adjustable, meaning they are exposed in the pictures. All of the screws are adjustable... the difference in the later carbs was the EPA standards that kicked in in 80 caused Yamaha to plug the towers in an attempt to keep folks from fooling with them. The screws are recessed in the towers but still fully adjustable.