1979 xs1100s ignition issue

[TopCatGr58]

Hey Greg,

I think he meant to say he took the lines off, the fuel lines to clean them.

Don, you got spark and you got it to try to start when you had fuel poured into the plug holes/cylinders directly. The XS11 ignition system used a wasted spark system,m so 1-4 plugs fire at the same time, and 2-3 will fire at the same time. So...if you had some fuel in the cylinder that was on the exhaust stroke when the spark fired, it would make a backfire.

You have allegedly professionally cleaned carbs, spark, but no run! Will run with added fuel to cylinders, but not with just the carbs. Sounds like either a fuel supply problem, or fuel delivery problem of the carbs themselves...could be from a vacuum leak. Need to check the intake boots and synch port caps as sources for the leak.

You also have a leaky petcock. But as long as fuel is flowing thru it to the carbs it shouldn't keep the bike from running. You have an SF(Special), do you still have the fuel control Octopus device?? Are you using the choke/enrichener when trying to start it? Do you have the fuel lines plumbed correctly?? There's a jet in the bottom of the float bowl, may have been missed, if clogged, choke/enrichener won't work.

T.C.

[BA80]

I've gotten. It to fire a couple times and I took the likes off also to clean and tried to turn it over and it is obvious I got fire cause I got fire out of them. Unless the pickup coils are something else?

Don't know what the "likes" are but put some fresh plugs in it and see how it acts.

Pick up coils are under the left front engine cover. Sends the signal to the TCI to fire the coils. But if you have fire to all 4 plugs that's not going to be the problem.

[mikubuilder]

Welcome Dondon , for $250 it's a steal

since you have tank of, you can do a few quick checks with multimeter to see if your electrical system is up to par

first make sure your battery has over 12V
second when you turn the key to ON you have still 12V after first two fuses (looking from left to right)

third check resistance of your coils, primary and secondary

if that checks good, you can see if your red/white wire to coils is getting 12V, with a key ON

it might be helpful, to go through entire system and clean up ALL ground connections, including one under the reg,/rect. or even go extra mile and add a ground shunt from battery straight under the reg./rect.

just my 2 cents

[dondons1984]

I've gotten. It to fire a couple times and I took the likes off also to clean and tried to turn it over and it is obvious I got fire cause I got fire out of them. Unless the pickup coils are something else?

[BA80]

Plugs are cheap and easy. It won't hurt.

Spark plugs do break down inside over time.

Have you checked you pick up coils?

Why did the PO park it?

[dondons1984]

Tank is shiney the guy took care of the bike and drained and maintained

[dondons1984]

Carbs have been rebuilt. So spark plugs are probably my problem?

[BA80]

So my 791100s sat for 17 years. Spark plugs look black and I am wondering can they go bad after time? Is that why my bike tries to start but wont ?

Triple clean on the carbs and new plugs are in your future.

How does that fuel tank look after 17 years? That'll be how those carbs look inside. Clean 'em both GOOD.

[motoman]

So my 791100s sat for 17 years. Spark plugs look black and I am wondering can they go bad after time? Is that why my bike tries to start but wont ?

That and carbs plugged up tighter than a drum after 17yrs. sitting........

[dondons1984]

old plugs

So my 791100s sat for 17 years. Spark plugs look black and I am wondering can they go bad after time? Is that why my bike tries to start but wont ?

[oldyam80sg]

Rebuilt by who?-best thing to do is get on other parts of this site that deal with carb cleaning and do them yourself.Don't trust anyone to rebuild them as many have seen broken float bowl posts,broken tips of needles and wrong parts put on.For years i relied on a guy by me who had a shop-long story but that shop closed up,and there is not too many places around that have people that can actually work on them that know these bikes.Most shops wont even touch a bike this old.This site is the best for knowledge.

[dondons1984]

They have been rebuilt professionally

[bikerphil]

If it sat for 17 years, the carbs most definitely will need cleaning, have you done that?

Edit: I see that they have been drained, so they shouldn't be too bad. Does it run with the choke but not run with the choke off?

[dondons1984]

here is a link to the bike when it was in the back of my truck

http://s1274.photobucket.com/user/dondons1984/library/?sort=3&page=1

[dondons1984]

ok so update. went to go start it after putting a little premium gas in the cylinders then put the spark plugs back on. went to go start it without the tank on since i have a leaky petcock and it almost turned over. now when I try sometimes I get a backfire that sounds like a damn tank went off and makes me jump every time. So here are the questions

Am I getting spark then?
Is there something clogging the exhaust?

I know I am not getting fuel so I am going to focus on the petcock but what does this sound like to everyone else? Do I need to focus on other stuff also? timing?