New guy with an 79 XS1100

[ninety4point6]

Picked up a xs1100 on craigslist for $150 about a month ago.
Put a new battery in it and rebuilt the carbs. Runs pretty good and had a good first ride today. Have about $300 in it now. Think I'm doing pretty good.

Here's a picture of it in the state it is right now:



Next modification is some drag bars.

Let me know what you guys think.

[cywelchjr]

I think that's an 80 not a 79. This is based on the lack of the nub for the kick start and the slotted rotors. There may be other cues I'm missing but those are the things that are standing out to me.

[ninety4point6]

I think that's an 80 not a 79. This is based on the lack of the nub for the kick start and the slotted rotors. There may be other cues I'm missing but those are the things that are standing out to me.

It could be an 80. The guy didn't know much about the bike and I don't really either. He told me it was a 79, but who knows.

Some of the carb rebuild parts that I got in the 79 kit did not work, so it probably is an 80.

Whats the best way to tell?

[petejw]

hi ninety4point6,

nice score on the bike and welcome to the group,

if u can put up the start of ur vin number, we'll be able
to tell u which model bike u have.

[ninety4point6]

hi ninety4point6,

nice score on the bike and welcome to the group,

if u can put up the start of ur vin number, we'll be able
to tell u which model bike u have.

Thanks.

I'll check it tomorrow. It's back in the storage shed now.
Now I'm thinking it might be an 80.

Guess we'll see tomorrow.

[petejw]

here u go, let us know what u find out.


US Models:

Year
Model
Serial #
Color(s)

1978 XS1100E 2H7-000101 Macho Maroon
1979 XS1100F 2H7-020101 Magenta Red, Indigo Blue
1979 XS1100SF 3H3-000101 Carmine Red, Black Gold
1980 XS1100G 3H5-000101 Diamond Silver, New Ruby Red
1980 XS1100SG 3J6-000101 Black Red, New Ruby Red
1980 XS1100LG 4H3-000101 New Yamaha Black
1981 XS1100H 4R1-000101 Indigo Blue
1981 XS1100SH 4R0-000101 Black Blue, Cardinal Red
1981 XS1100LH 4W1-000001 New Yamaha Black
1982
XJ1100J
10M-000101
New Yamaha Black, New Ruby Red

[ninety4point6]

Cool, thanks for the list!

[BA80]

Frame has been hacked up pretty bad. That seat looks about as comfortable as a church pew.

[fredintoon]

Picked up a xs1100 on craigslist for $150 about a month ago.
Put a new battery in it and rebuilt the carbs. Runs pretty good and had a good first ride today. Have about $300 in it now. Think I'm doing pretty good.
Let me know what you guys think. - - -

Hi Trent,
considering what I paid for mine you did brilliant!
That said, put a front fender on it.
Not only does a front fender keep the rain out of your eyes, it stiffens those flimsy front forks.
Additionally fitting a Tkat fork brace stiffens it even more.
Do something about it's nekkid arse too.
A better class of seat will work wonders for your comfort.
Some running lights and signals will work wonders for your safety.
BTW, I'm with Cy, that's an '80. If the sticker on the steering head sez Sept (or later) 1979 it's a 1980 model.

[cywelchjr]

Many guys look at the date of manufacture and take that to be the model year, and that is so very often wrong. Depending on the year, model years can vary as to when they start, and can even start at different times for different models. The only thing that will tell you is the VIN number or the compliance sticker, which will tell you the year's safety and emissions standards it complies with, which will be the model year.

[ninety4point6]

Frame has been hacked up pretty bad. That seat looks about as comfortable as a church pew.

How is it bad? The seat isn't supposed to be comfortable obviously.

Hi Trent,
considering what I paid for mine you did brilliant!
That said, put a front fender on it.
Not only does a front fender keep the rain out of your eyes, it stiffens those flimsy front forks.
Additionally fitting a Tkat fork brace stiffens it even more.
Do something about it's nekkid arse too.
A better class of seat will work wonders for your comfort.
Some running lights and signals will work wonders for your safety.
BTW, I'm with Cy, that's an '80. If the sticker on the steering head sez Sept (or later) 1979 it's a 1980 model.

I have all the stock parts. I just wanted to make the bike as light as possible. The plan for this bike is an ultra low budget drag bike. Streetability isn't a huge concern.

Many guys look at the date of manufacture and take that to be the model year, and that is so very often wrong. Depending on the year, model years can vary as to when they start, and can even start at different times for different models. The only thing that will tell you is the VIN number or the compliance sticker, which will tell you the year's safety and emissions standards it complies with, which will be the model year.

Yeah, I still have to check the vin out. Should be able to check it out later tonight. School and work are killing my free time.

[ninety4point6]

The vin starts with 3J6, so it's in fact a 1980.

Thanks for letting me know guys.

[81xsproject]

Okay, so now onto one issue I heard you mention. You said that SOME of the parts from the 79 kit didn't work in your carbs. However, I am guessing that those 137.5 mains screwed right in. And, if your kits came with slide needles, those might fit too...? Did you use the brass needle valves in the 80's seats?

[natemoen]

Jesse brings up a good point. If you ordered '79 carb kits and you now see your bike is an '80 then a lot of things might be wrong. '80 was a transition year for the carbs so depending on where in the model year your bike was made you have different carbs.

You need to look in your carbs and see if there is a hole drilled from the main jet tunnel to the pilot jet tunnel. If there is a hole then you need to plug the pilot jet tunnel and use the larger 137.5 main jet. If there is not a hole then you need to leave the pilot jet tunnel open and use the smaller 110 main jet.

Also I would suggest if the original jets that were in the carbs are not damaged and just need to be cleaned use then. So many problems seem to come about because people use carb kits that really are not correct. The pilot jet seems to be the biggest problem (should have 6 holes in a 2-1-2-1 pattern around the outside) second problem seems to be the needle jet not being the same taper causing problems.

Another thought, was there an aluminum screw in the pilot jet tunnel?

[ninety4point6]

Okay, so now onto one issue I heard you mention. You said that SOME of the parts from the 79 kit didn't work in your carbs. However, I am guessing that those 137.5 mains screwed right in. And, if your kits came with slide needles, those might fit too...? Did you use the brass needle valves in the 80's seats?

The 137.5 mains screwed in. I used the stock needles.

Jesse brings up a good point. If you ordered '79 carb kits and you now see your bike is an '80 then a lot of things might be wrong. '80 was a transition year for the carbs so depending on where in the model year your bike was made you have different carbs.

You need to look in your carbs and see if there is a hole drilled from the main jet tunnel to the pilot jet tunnel. If there is a hole then you need to plug the pilot jet tunnel and use the larger 137.5 main jet. If there is not a hole then you need to leave the pilot jet tunnel open and use the smaller 110 main jet.

Also I would suggest if the original jets that were in the carbs are not damaged and just need to be cleaned use then. So many problems seem to come about because people use carb kits that really are not correct. The pilot jet seems to be the biggest problem (should have 6 holes in a 2-1-2-1 pattern around the outside) second problem seems to be the needle jet not being the same taper causing problems.

Another thought, was there an aluminum screw in the pilot jet tunnel?

I'll have to check the differences. Bike runs pretty good. I'll have to do a WOT pass and check the plugs and see if it's rich or lean.