xs1100 MNS Carbs

[gatoraid]

I'm rebuilding a MNS, trying to get it to factory. Me and my dad have a hobby rebuilding bikes, and I would like to keep this one for myself. I need to get the following:

Full Set of Carbs.

*Edit*

I'm kinda new to the bike, but the year I need is 79 -80

[DGXSER]

Hey Gatoraid, welcome to XS11!!

The MNS was only made in 80 and 81, and primarily was a cosmetic options package. As for the carbs, Yamaha or rather Mikuni made a relatively big change in the carb design in the 80 model year, So any 80 or 81 model year set will work fine. However, the MNS model did have the carb bodies painted or powder coated black and the tops of the carbs covered in gold chrome.

So, what your after depends on what your willing to do. If you have the resources or patience to get the caps gold and the bodies black, then any 80-81 model carbs will match, otherwise, your looking for a needle in a haystack.

[spyder]

XS1100 Midnight

Gatoraid,

Typically the carbs for the 1100 are broken down into the 1978-79 and 80-81 year models. There are minor differences between the models. I believe the Specials you are referring to are in the 80-81 group. There was a major change in the carb design beginning in 80. Air mixture screws/pilot and main jets/ manual vs. cable choke, etc..Unless you are just trying to get period correct, any in the date range will do. I build these for a living and have sold some to others on this site. The specials are painted black (why, I don't know). They are a pain to restore. If you need any help concerning these carbs, let me know...be more than happy to help.

Spyder

[DGXSER]

Spyder,

Not to be overly critical, but....

The "Special" models carbs were not painted black, only the "Midnight Special" models. Also, the choke mechanism did not change until the XJ model in 1982. The big change between the earlier and later model carbs was the elimination of the external vents, and the change from drawing the pilot jet fuel through the main jet with a plug in the pilot jet tower to an open pilot jet tower. That is what changed the main jet sizes down dramatically, as it now did not carry the pilot jet fuel.

As I believe you were stating, even the 78-79 model carbs will work and run on an 80-81 model engine, or even an XJ for that matter. However the earlier 78-79 models have the external vents, and the airbox for the later models does not have the nipples drilled out to accept the vent lines. All things that can be overcome though.

As to being a pain, these carbs are relatively easy to work on from a rebuilding and cleaning standpoint. The only part that is really tricky is the butterfly seals, but fortunately those rarely need attention.

However, I would not want to go through the trouble of painting or coating a set back to the black. And the gold chrome is a real $$ factor. But then, anyone who has a factory set of MNS carbs is probably not giving them away either! For me, I'm not THAT particular about the look of my bikes, but then I never really went to full on "Restoration" as much as a "renovation".

[gatoraid]

Carbs

Ok, thanks for the advise. So basically I can just look for the 80-81 model carbs and be fine? Know where I might be able to get ahold of a set?

[gatoraid]

Ok, I have the chance to buy 1979 xs1100 carbs, will this work for me?

[DGXSER]

The bike will run on the 79 version carbs just fine.

The only real variance from the stock carbs as far as installation or performance is that the 78-79 version has the external float bowl vents. There are two T's between the carbs the same as your fuel Ts would be on the 80-81 versions, but higher. These lines ran to the air box, to the nipples above the gap between the 1 and 2 velocity stacks and the 3 and 4 vlocity stacks. On your MNS, those nipples are closed off. So they will not let the bowls vent if you push the hoses onto them.

You can just let the line sbe open to atmosphere and tie them up to frame area to keep them higher than the float bowls. Or you can drill out the nipples on the air box and connect them in there.

[gatoraid]

Carbs

Thanks, going to order them now!

[natemoen]

Did your bike not come with carbs? Is you have the old carbs I might be willing to take them off your hands, pm me.

[gatoraid]

You would not like the carbs the bike came with. We took two pairs of carbs and tried to make one set, which was a bad idea. We had one that was over gasing the engine, causing the temp to hit 500 within like 30 secs of being on. Tried to adjust it, but was unable too. Found out that one of the jets was drilled out inside of the carb. This is why I'm getting a new set.

[natemoen]

Heck, if your just going to toss them I'd take em.

[CatatonicBug]

You would not like the carbs the bike came with. We took two pairs of carbs and tried to make one set, which was a bad idea. We had one that was over gasing the engine, causing the temp to hit 500 within like 30 secs of being on. Tried to adjust it, but was unable too. Found out that one of the jets was drilled out inside of the carb. This is why I'm getting a new set.

You'd be amazed at how "repairable" these carbs are. The things you mention definitely do not make them trash. Unless the carb bodies are physically broken, they can almost always be brought back to life.

[FANNING507]

Item #310267283227 on Ebay. $99.99 initial bid. But they are original. Low mileage bike; might be worth a look. 2 days left to bid.

[cywelchjr]

You'd be amazed at how "repairable" these carbs are. The things you mention definitely do not make them trash. Unless the carb bodies are physically broken, they can almost always be brought back to life.

I would agree with you there. There is very little short of actual damage to the body of the carb that can't be fixed. Even broken float posts can be fixed, and IMHO can be fixed as good or better than new. Only once did I toss a set of carbs, that was a set I bought off ebay, but it was because everything was froze in place (butterflys wouldn't move, slides were stuck really good. I know I could have gotten them working, but I bought them based on they were supposed to be good carbs. Seller gave me my money back and when he said he didn't want them I tossed them. Mainly because mine were in far better shape (XS400 carbs).

[DGXSER]

I have a set I am close to calling done!! No broken float post, but broke an extractor off in a pilot jet, all four mix screws refuse to budge even using an extractor (very gently!! One broken is enough!! BTDT!!) and all four butterfly valves are BENT!!! I have no idea how the heck you bend them, but they are bent!!