1981 XS1100LH trouble starting

[gpk321]

Hey everyone, this is my first post although I have been monitoring this forum for quite a while and reading up on different things. I want to go ahead and apologize first if this question has already been asked as I'm sure it most likely has. I tried to navigate and find this exact problem but couldn't seem to find one that fit the criteria exactly that I was experiencing. So anyway, I have a 1981 XS1100 midnight special rebuilt and cleaned the carbs, bench synced the carbs, changed the oil, changed the plugs, good spark, engine appears to have good compression, electrical has been all redone and works like a charm, brand new battery, starter seems to be running good, no bent valves or any of that and it will only start for a few seconds with starting fluid and then dies out. I had a fuel source connected to it, but it did not seem to make a difference. This may be normal as the bike hasn't been run and has been neglected for 20+ years but I have kind of hit a roadblock and don't really know where to go now. Also the starter motor seems to make a really bone chilling crackling and grinding after the engine cuts out I don't know if this is normal or not. One more thing to note the air box has been removed and it is currently being ran with no filters on the end because I don't have any at the moment I don't know if this would have anything to do with it either. Any incite you experts have would be greatly appreciated to get this thing running and once again I really apologize to post something that may have already been posted before. Please don't hate me and thank you all very much!

[dbeardslee]

Running it without an air filter will make it run lean, but it should still run. One of the first things you should do with a bike that has been neglected is to go through the electrical connections and clean them all. Pay particular attention to the handlebar kill switch as they're notorious for getting corroded on the inside. If you've got a multi-tester you might check your resistances to your coils, across the high tension wires, and to your pickup coils as well.

If you look in the tech tips section, you'll find some good threads on what to do with a neglected XS.

You might also check for obstructions inside the exhaust - for some reason mice sometimes like to build nests there.

[nzemke]

Did you check float height on the carbs? It might be restricting gas from flowing. Also check to make sure the pilot screw tip isn't broken off in the carbs.

[dbeardslee]

Just noticed you already checked the electrical - sorry for the redundency. When you said you had a fuel source connected, did you bypass the octopus and go straight to the carb "T"s? If you didn't you might try connecting fuel directly to the "T"s. The octopus is vacuum operated and they're pretty problematic sometimes. Or at least make sure you've got a good vacuum line connected to the octopus.

[TopCatGr58]

Hey GP,

Okay, first you say the carbs were cleaned...BY WHOM?? Did you do the work or a shop? IF you did...there's a jet that is often missed down in the actual Float BOWL which is easily clogged, and if not cleared, then you get no fuel with the enrichener activated, and so can't start. Your bike starts/fires with starter fuel, so it does sound like it's just not getting fuel!
Did you fully disassemble the carbs....vac. slides, all of the jets, the emulsion tube out up from the middle of the carb body, pilot screws removed....they are hidden under sealing brass/aluminum caps in towers on the front top of the carb bodies? Then verify that ALL passages are clear with carb cleaner spray.

Another point was made regarding the Octopus...the fancy vac. controlled fuel valve secured to the #2 carb with a bunch of fuel hoses going into and out of it. IF you still have it in place, you can just simply BYPASS it by putting the petcocks on PRIME...provided you have all of the fuel lines plumbed correctly. Do you have fuel in the float bowls?

Another thing is ensuring no vacuum leaks...the carb intake boots can form leaks where they mounts to the heads due to age/heat. Also the synch port rubber caps also harden, should be replaced as well.

T.C.