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1981 XS 1100 Special – B 4RO
It’s totally stock I've owned it since it was new. Its been stored for 21 yrs got it back on the road last Sunday.
I believe I have a carburetion problem. I am running a few tanks full of fuel treated with ring-free from Yamaha. The local mech told me to do that before I pay him .
Here’s the problem I'm having. She doesn’t want to start when cold . It tries to pop once then she just cranks and cranks. At this point if I spray some starting fluid into the air cleaner box she fires up right now. Then with some creative throttle control I can keep it running while I get the seat back on . When its cold like this it pops and backfires but as soon as I put some power to it she goes strong . After I go around the block a few times and she is really warmed-up she will idle on her own. However when I give it some throttle it will stay revved up at about 4500 to 5000 rpms when in neutral. When I let the clutch out the power comes down to normal. Or when it is revved like this in neutral if I pull the choke lever out to the first click she will idle normal and actually will run down the road very well . The local guy told me that the problem is most likely with the low end or slow jets for idling. My Clymer manual doesn’t specify which jets are starter jets. It just gives me the # 32.5 I worked as an auto mech for a few yrs a long time ago so I have some idea on how not to turn a wrench or when not to use a hammer. I have been though this bike from headlight to tail light. Have checked for head leaks and compression, all good. Mechanical and vacuum advance check out all good. (When I pull the vacuum line off the advance she will power down but the advance checks out at 5lbs. vacuum.) Intake boots check out no leaks. New coils, cause the old ones checked out on the low end and I wanted to be sure. Timing is right on. Have had the carbs torn down to there basic elements , toothbrush and Q-tip cleaned, all the jets seem to be open when I shoot carb spray through them. Put them back together with all the stock parts except for new needle and seat in all four (The problem was the same with the old needle and seat. I replaced them because there was some leakage . ) Floats are set at the same on all four. I put the carbs back together and color tuned them . But the problem is still the same. Strong at power , struggles, pops and backfires at idle when cold. One other thing if I hold the throttle at about 2000 rpms when cold she will continuously sputter and pop. Go past that we’re good.. This bike is very clean inside no cracked or worn wiring anywhere and all connections and solders are good. Have not touched the main ignition module. She had none of these problems when I put the bike away years ago.
Any help or advice would be appreciated.
Don’t fall Down (That’s if it will start up.)
Keith
It’s totally stock I've owned it since it was new. Its been stored for 21 yrs got it back on the road last Sunday.
I believe I have a carburetion problem. I am running a few tanks full of fuel treated with ring-free from Yamaha. The local mech told me to do that before I pay him .Here’s the problem I'm having. She doesn’t want to start when cold . It tries to pop once then she just cranks and cranks. At this point if I spray some starting fluid into the air cleaner box she fires up right now. Then with some creative throttle control I can keep it running while I get the seat back on . When its cold like this it pops and backfires but as soon as I put some power to it she goes strong . After I go around the block a few times and she is really warmed-up she will idle on her own. However when I give it some throttle it will stay revved up at about 4500 to 5000 rpms when in neutral. When I let the clutch out the power comes down to normal. Or when it is revved like this in neutral if I pull the choke lever out to the first click she will idle normal and actually will run down the road very well . The local guy told me that the problem is most likely with the low end or slow jets for idling. My Clymer manual doesn’t specify which jets are starter jets. It just gives me the # 32.5 I worked as an auto mech for a few yrs a long time ago so I have some idea on how not to turn a wrench or when not to use a hammer. I have been though this bike from headlight to tail light. Have checked for head leaks and compression, all good. Mechanical and vacuum advance check out all good. (When I pull the vacuum line off the advance she will power down but the advance checks out at 5lbs. vacuum.) Intake boots check out no leaks. New coils, cause the old ones checked out on the low end and I wanted to be sure. Timing is right on. Have had the carbs torn down to there basic elements , toothbrush and Q-tip cleaned, all the jets seem to be open when I shoot carb spray through them. Put them back together with all the stock parts except for new needle and seat in all four (The problem was the same with the old needle and seat. I replaced them because there was some leakage . ) Floats are set at the same on all four. I put the carbs back together and color tuned them . But the problem is still the same. Strong at power , struggles, pops and backfires at idle when cold. One other thing if I hold the throttle at about 2000 rpms when cold she will continuously sputter and pop. Go past that we’re good.. This bike is very clean inside no cracked or worn wiring anywhere and all connections and solders are good. Have not touched the main ignition module. She had none of these problems when I put the bike away years ago.
Any help or advice would be appreciated.
Don’t fall Down (That’s if it will start up.)
Keith
Guess where I'll be this weekend. By the way what does a vacuum sync cost?
I did take out the brass caps and pilot screws. and I know now that I never cleaned any jets in the removable part of the float bowls. I can remember seeing them now and when I realized what you were talking about It was a total Duh! moment for me 
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