Good Start... Then No Start

[thainglo]

Trying to clear the last hurdle on my 1100 rebuild. Had it running great, - took for a couple of spins around the block, now it has difficulty starting up (as in - won't!). I've had the carbs apart twice with all the parts soaking in SeaFoam, then reassembled. When I get the carbs mounted back on the bike, airbox installed, and hook up my temp tank, the bike fires up and purrs along like a happy kitty.

Then, a day or so later, when I try again, just turns over... and over... and over. Just happened again, after the second carb rebuild, so thought I better come to you guys for ideas. Was going to hook up my new CarbTune and was surprised when I couldn't get it to fire up. Just had one or two backfires out the back.

All the carb parts look in great shape with no visible wear on anything. Air/fuel mixture screws are backed out 2.5 turns. Vacuum line to the petcock is plugged.

I've checked spark on all four cylinders, all good. Same with compression. I'm just puzzled on why it will run great right after the cleaning, and then not want to start afterwards...

Ideas? Other info I can provide to help with the diagnosis?

[arsenic]

Lets look at the logically. You clean the carbs and it runs good for 2 or 3 days. Than it doesn't. What would cause the jets to get clogged again? You're fuel tank. Check if you have any sediment and/or rust in your tank. Clean and seal with POR-15. Otherwise enjoy cleaning the carbs every 2 days.

[KatKrak]

Not attempting to fire at all ?
Check the safety switch on the clutch perch and on the kickstand. Check the kill switch on the handle bar. You've got an old bike there,and things wear out and corrode. Mine gave me all sorts of problems, exactly as you described. For me, I just disabled the kickstand and clutch switch. Cleaned up the kill switch on the bar and coated it with dielectric grease. No more problems.

*edit* just re-read your post, seems it DID try to start.
Could be like Arsenic said, crap in the tank, I'd start looking there

[thainglo]

Lets look at the logically. You clean the carbs and it runs good for 2 or 3 days. Than it doesn't. What would cause the jets to get clogged again? You're fuel tank. Check if you have any sediment and/or rust in your tank. Clean and seal with POR-15. Otherwise enjoy cleaning the carbs every 2 days.

Thanks Arsenic - I wasn't 100% clear on the situation, but agree with your logic. I haven't hooked up the fuel tank, just the temp tank (water bottle with a 1/4" hose barb screwed into the bottom.

After cleaning the carbs, I'd fire it up and let it run for a few minutes just to check that everything seemed ok. Then, it would sit for a few days until I had a chance to play with it again. Next time I'd try and fire it up, kaput...

Fresh gas being used for the testing...

So, is there anything screwed up in the carbs that would fail after a few days? I'm lost.

And - per Arsenic's suggestion, not too excited about tearing apart the carbs every time the bike sits for a couple days!

[HemiKat]

Check your plugs. Ive got a $20 Bill that says they are fouled. Im guessing either a needle and seat leak, or the float heigh is off.

Something is letting fuel into the cylinders and when you try and start the bike, it burns the excess fuel and fouls the plugs, which prevents it from starting.

[thainglo]

I'll check the plugs again. Fouled would be black and oily, right? When I checked for spark, they looked pretty clean, but that was before the second time it wouldn't turn over.

Temps have been in the 70s and 80s when I was trying to start it up. I was cracking the clutch open a bit and shooting some carb cleaner in to give it a boost. Will that foul the carbs before it gives a chance to fire up?

The float heights were set within spec (14.6 +/- 1.0mm). Floats were solid, no leaks.

I've been removing the fuel bottle each time, so no extra fuel is getting into the float bowls between attempts.

Thanks for the ideas, keep em coming!

[Kreylyn]

Check power (voltage ) on the battery 3 times... key off, key on, stater turning over.

Also check power to the coils (orange/white stripe) with power on, and turing over.

Note exact votage readings.

Not saying it IS the problem, but lets rule out any electrical grimlins...

krey

[thainglo]

Check power (voltage ) on the battery 3 times... key off, key on, stater turning over.

Also check power to the coils (orange/white stripe) with power on, and turing over.

Note exact votage readings.

Not saying it IS the problem, but lets rule out any electrical grimlins...

krey

Good idea! Just went out and ran through the voltage checks. Readings below are right after taking the bike off my battery tender (those things are AWESOME!)

Battery:

Key Off: 13.27

Key On: 12.8

Start: 11.0

Left Coil:

Key Off: 0.06

Key On: 11.0

Start: 6.67

Right Coil:

Key Off: 0.06

Key On: 10.97

Start: 8.00

Voltage drop between the coils is interesting. When I pulled the plugs to check condition and verify spark last week, they would spark across the electrode when grounded to the carb rail.

Thoughts?

And thanks for the ideas guys, this is helping!

[Kreylyn]

Good idea! Just went out and ran through the voltage checks. Readings below are right after taking the bike off my battery tender (those things are AWESOME!)

Battery:

Key Off: 13.27

Key On: 12.8

Start: 11.0

Left Coil:

Key Off: 0.06

Key On: 11.0

Start: 6.67

Right Coil:

Key Off: 0.06

Key On: 10.97

Start: 8.00

Voltage drop between the coils is interesting. When I pulled the plugs to check condition and verify spark last week, they would spark across the electrode when grounded to the carb rail.

Thoughts?

And thanks for the ideas guys, this is helping!

Key off at the coils should be 0 (no power at all).

The starter running and the coils under 10v is very possibly a problem for weak spark.

This could be a sing of a bad battery, but also could be a wiring issue. If wiring issue, see below...

I would get 2 14-16 guage wires that will reach from the coils to the battery, and do a quick test. Put female spade connectors on one end, strip the other ends. Connect them in place of the coil orange/w wires. Right when you are ready to start the bike, press the other end to the positive battery post to energize the coils directly from the battery. Press the starter and see if it starts.

If it starts that way, but won't with the orange wires hooked up... you have an electrical issue that is dropping the voltage to your coils causing hard starts.

While some disagree, I've spent some time researching this between several pre kats. I think the coil relay mod is a good alternative to completely replacing all of the wiring that causing this issue.

Krey

[gwigs]

Had the same issues with my 1100,would only run well for a while after a clean,wouldnt idle and ran rough at low rpm,pilot jets kept blocking up..flushed the tank and the problem dissapeared.
I reckon Arsenic is right on the money there.

[arsenic]

Had the same issues with my 1100,would only run well for a while after a clean,wouldnt idle and ran rough at low rpm,pilot jets kept blocking up..flushed the tank and the problem dissapeared.
I reckon Arsenic is right on the money there.

I already know I am, but it's nice of you too tell me.

[thainglo]

Had the same issues with my 1100,would only run well for a while after a clean,wouldnt idle and ran rough at low rpm,pilot jets kept blocking up..flushed the tank and the problem dissapeared.
I reckon Arsenic is right on the money there.

Good advice, and I spent a couple of hours flushing the tank. Only issue in this situation is I haven't had the original tank hooked up to the bike, only my water-bottle test tank.

I'm stumped.

[phantasm]

crap in the fuel lines?

[thainglo]

Got it!

Dirty plugs! Pulled all four, didn't think they looked to bad, but took a wire brush and some brake cleaner to them. All shiny, put them back in and could barely get my finger on the starter button before the beast fired to life. Sweet!

[HemiKat]

Dirty plugs! Pulled all four, didn't think they looked to bad, but took a wire brush and some brake cleaner to them. All shiny, put them back in and could barely get my finger on the starter button before the beast fired to life. Sweet!

Thank you, Thank you very much. Where do I go to claim my prize?