Starting trouble

[Avi8er]

So....my bike is a 79 xs1100 special. The bike runs ok once you get it started, but it will not start cold with the starter. I can push start it in second and it will fire right away. If it's good and warm it will start with starter but refuses when cold. Pretty sure the carbs could use a sync and clean, but I figured If it will roll start with no problem something is up.

[GLoweVA]

Alright, I'll give this a crack.
-runs okay after start
-starts okay after warm
-can push start it okay.
-will not start cold with starter.

A little more info is needed: When you try to start it 'cold' with the starter, does the starter spin? or is it just a click?
If the starter spins (and thus the engine too) do you have the choke fully open?
Do you get any sputters/ignition at all?

[jwhughes3]

Battery voltage

Make sure with volt meter that voltage when cold is not dropping below 10.8V while starter is cranking or no starty....

When push starting, a marginal battery with only 11V can start the bike. You could try with a battery booster attached to test.

Where are you that its "cold" this time of year? Thats where I want to be!


John

[GLoweVA]

Make sure with volt meter that voltage when cold is not dropping below 10.8V while starter is cranking or no starty....

When push starting, a marginal battery with only 11V can start the bike. You could try with a battery booster attached to test.

Where are you that its "cold" this time of year? Thats where I want to be!


John

I totally agree John, but if his starter isn't even spinning when cold, then there's othere issues to look at.
That's why I wanted more info before I went further with the diaganostic plan.

He's in Chicago, and I doubt that it's that cold up there right now.

[Avi8er]

Starter cranks fine and turns engine over well it seems. Cold just means same as outside temp lol. I'm in Southern Indiana and it's been over 100 here for a while it seems. I've tried with choke full open, half open, with a little throttle input. It seems to crank strong but just wont fire. Doesn't really seem to even pop or try to fire. But, like I said, I can throw it in second after trying and roll down a slight incline an it will fire right away. Haven't tried putting a meter on it yet.

[skids]

ballast resistor bad?

[skids]

I wonder if your starter button is somehow also activating the kill switch? I don't even know if this is possibe in the handlebar unit. Weird wiring maybe?

[GLoweVA]

The ballast resistor is cut out during starting(with the starter), but otherwise is in the circuit all the time.

Skids, that's a good point about the starter button and kill switch are in the same housing. Maybe worth a look.

This is a tough one.
It only happens when it's not warmed up.
Once running, and shut off, the bike will start back up with the starter.

SO, no spark when cold.(ie not warmed up), but can push start it.
It's got to be some connection/wire thing that when it gets warm it works.

[TopCatGr58]

Hey there Avi8r,

As Hughes has stated, sounds like even though the starter seems to spin over okay, your battery is getting weak, and the voltage required to power up the TCI isn't there, so the motor spins, but there's no spark to ignite. When you push start it, you've taken the voltage load off of the battery by bypassing the starter circuit/load, and so more voltage is availible to the TCI and it can then make sparks, and start!

There have been recent threads on this phenomena, I've experienced it with just a 1 year old battery that I let get dried out a bit during winter storage, and so it just wasn't strong enough. Put a volt METER across your battery terminals and see how low it goes during cranking. However, that voltage is probably higher than what's actually at the ignition circuit due to the route it has to take thru the harness, fuse block, etc.! Put the meter on the ignition fuse and measure again while cranking.

Put a jumper battery on to the battery and see If it will start that way. I actually put the jumper onto the ignition fuse to help provide plenty of juice to it without getting drained thru the harness, and let the weak battery do the starting action, and it started that way which lead me to diagnose the weak battery. New battery solved the problem!

Check your connections as well, clean them, grounds, etc.!

T.C.

[Avi8er]

Breaking out the multimeter today to dig further. Will post my findings.