Fuel Mileage

[Tired Old Man]

I was getting a raw gas smell and poor mileage, like 17mpg or so. I pulled the carbs last Thursday and put in two size larger jets. They aren't the right ones yet for the header but the correct jets will be here this week. I don't know why I didn't check the jets all of the other times I had the carbs off but it was just one of those things. One of the jets wasn't even finger tight. I think that would explain the raw gas smell. I was probably pulling gas around the jet. The other jets just looked bad. Put it all back together, color tuned and re-synced the carbs. My bike ran like a totally different machine. It still isn't perfect but getting closer. My mileage was 35.9 mpg just local running around. Needless to say I am much happier.

Now I have another issue. My bike doesn't like to be chocked and according to the original owner it never has. After sitting overnight, it is hard to get started in the morning, kind of like me. Once it starts it can sit for 7 or 8 hrs and will fire right up. Any suggestions?

[boyat68]

Tired Old Man:

The XS1100 carbs do not have a choke, rather it has an enrichment circuit. That is the butterflies are left where they are and the lever allows a metered amount of fuel to flow into the throat of the plenum, either half or full on. If your enrichment circuit is not functioning correctly, then your setup of your carbs is most likely not correct as it allows too much fuel to flow into the pickup chamber. It looks like you need to re-clean your whole carb setup and include the enrichment circuit as well as your Pilot screws.

By the way you should post what type and model of XS you have as that will allow our gurus to trouble shoot your problem more precise.

[mro]

chocked, chock·ing, chocks

1) To fit with or secure by a chock: The XS's wheels were chocked and chained down.
2) Nautical To place (a boat or XS) on chocks.

What boyat68 said.
When ignition and air be good that leaves fuel...
From reading your post...did you disasemble/clean the carbs?
Float height set?
How many turns out did the pilots wind up at?

When all is good these bikes fire right up, most on the first crank.


mro

[Tired Old Man]

My bike is a 79 Special. It did sit for 19+ years with a tank of gas. The carbs have been "cleaned" twice. I didn't know about not having a choke (hope this spelling makes you happy). Makes sense there is something wrong with the idle circuit. When it doesn't start right away it "stops" trying to start if I try to give it any gas at all. I am going to tear the carbs down again when the new jets come in. For the color tuning I ended up about a turn and a half out on 3 carbs and about a quarter turn more on #4. The floats were also "twisted" one side higher than the other and all were too high as well and that problem was corrected also.

[mro]

Specials be Special

My daily ride is a 79 SF and if I touch the throttle before it pops it will not start, warm or cold. Also if I don't twist the grip slightly right after it pops it will sputter and die.

19+ years with a tank of gas

I have a set of carbs on the bench right now from a 80 LG. Only XS I've worked on that has had that problem. Have yet to get around to dismantling them completely. Every few days or so I squirt a little cleaner in em. The float bowl fuel circuit was solid crud . Between a thin wire and cleaner have finally got the passage clear. When I get the energy will pull the top off and remove all the jets. Not to sure what I'll find.

Pilots out 1 1/2 turns are in the ball park. (you have stock air box?)
Various XSes, I've have had em from 1 to just over two turns out and one XS with pod filters and straight pipes were close to three.

Float height of 25.7mm worked for me (BS34 II carbs). I've played with it up and down but best performance has been at the recommended height.


mro
BTW,
35.9 mpg around town is better than most.
I get 30 to 33 mpg depending on how my right hand is behaving that day

[olebiker]

I have to roll on a bit of throttle to start my 80 special. I suppose I could use that lever down on the carbs but with a bit of throttle I don't need to. In colder weather it will need the extra fuel.

[Tired Old Man]

Thanks for the replys. I am going to make the jet changes I need and make sure the idle circuit is open. I do have pod filters not an air box. I hope to have all changes done by this weekend.

[egsols]

Full choke...no throttle when cold...fires right up.

No choke....little throttle when warm.....fires right up.

140 mains on 79sf with stock air box and 4 into 1 Jardine, pilots 1 3/4 out.

Only time it takes a bit is when its sat for a few days..but I believe thats down to the fuel drying up in the float bowls cause if I turn the fuel on for a minute, before I try, she fires right away.

How have you run your vent lines from the carbs?

It may be possible that the fuel is evaporating after sitting for a longer period, just enough to lower the fuel to prevent a good start. My theory only, a guru may have more insight. Anywho...just as a test, turn on prime while trying to start. That way you know you are getting sufficient fuel and if it doesn't start right away then it probably is your idle circuit. JAT.

[randy]

Right, mine does that when it sits for a week, especially sitting outdoors in the heat. I have to prime the bowls to get a quick start-up, then it's fine.

[Tired Old Man]

I think my bike just likes messing with me. The last 2 nights when I have tried to start it, it pops and dies. I pull the idle enrichment to the first notch and after a few cranks it starts and I have to shut the idle enrichment off. I have to keep it running for about 30 seconds and it will idle on its own. I'm hoping when everything is jetted right the problem will be solved. My son has an 78 Special and it starts on full rich and fast idles the way I wish mine did. Maybe some night his carbs might go for a walk and end up on The Old Man's bike! Thanks for all of the advice.

[egsols]

Maybe some night his carbs might go for a walk and end up on The Old Man's bike! Thanks for all of the advice.

Well yeah!! That's what sons are for....think of all the stuff they have borrowed off you over the years (sometimes without asking)

[olebiker]

Originally posted by egsols


Well yeah!! That's what sons are for....think of all the stuff they have borrowed off you over the years (sometimes without asking)

Ernie did you ever do that cause I sure never admitted to it. Course when the car is parked crossways in the driveway with the windows down in the rain and some stuff that could be puke in it would you admit to it?

[egsols]

originally posted by olebiker

Ernie did you ever do that cause I sure never admitted to it. Course when the car is parked crossways in the driveway with the windows down in the rain and some stuff that could be puke in it would you admit to it?

Admit to what? I was always the perfect son, considerate, polite, and obedient, never took stuff without asking, always put tools back where they belonged, never fibbed, you know...just like Eddie Haskell...perfect.

[olebiker]

Originally posted by egsols




Admit to what? I was always the perfect son, considerate, polite, and obedient, never took stuff without asking, always put tools back where they belonged, never fibbed, you know...just like Eddie Haskell...perfect.

Yeah that is what I remember too. Now if they would just leave me alone in my delusional state ...............