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Mayor of Simpleton
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Discussion Starter #1
I'm having an issue that seems to be getting progressively worse. The bike starts fine when cold, whether it's on the battery tender or off and unridden for an entire week, but is difficult starting when warm/hot (like after gas stops). Bike does not missfire or show any negative signs once started. The bike will turn over but just seems to lack the "oomph" to fire.

Bike has 23,000 miles and full service was performed (by myself and a friend) four months ago at 19,500 miles. Valves adjusted. Belts replaced. Several rockers replaced. New plug wires and Denso iridium sparkplugs installed. New fuel filter and internal fuel tank lines. Throttle bodies synced. We attempted to set the TPS but after 45 minutes of monkeying around were unable to--after everything was buttoned up we noticed the voltmeter itself had a broken lead. Bike does idle a bit high--generally about 1500-1600 RPM.

It's not the charging system. We get an excellent reading there.

Battery tests good as well, although it is about 2 years old and I've wondered if it could be bad under load.

I cleaned all the electrical connections around the battery, regulator and starter terminals--no help.

Fuel pump is working and the tank venting seems fine. (and no symptoms once started)


I'm leaning towards a bad starter, battery, or coils. Which of these would perform worse when warm though? What else could I be missing?
 

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Most of the time when an engine has trouble starting after it is warm from use, and then you can't start it, is usually due to a bad coil(s). I would check these first with regard to correct measurements i.e. OHM's, Volts, etc.
 

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start with the battery.. sounds like a flakey cell that get worse when hot. Low cranking voltage messes with the ecu, spark and injectors just when you need them the most.
 

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Is it ok to Jump it after riding it around and won't start anymore?
I jumped a few of my old JapBikes before and didn't affect anything.:think:
 

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Mayor of Simpleton
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Discussion Starter #6
When hot, it still runs perfectly and has no misfires. I can also push start it pretty easily (yay, no slipper:) ). Haven't had the opportunity to try jumping it.
 

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If it were me, i'd double check vavle clearences. The valves might just be sealing when its cold, but as she warms up, they are not closing fully and therefore causing the hot starting issue?

Just a thought.

MF
 

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Mayor of Simpleton
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Discussion Starter #8
Won't say valve adjustment is impossible, but I did sevice the bike 4 months and 3500 miles ago. The bike is also well broken in (23,000 miles) and we did not have to replace any of the half rings so I don't expect much movement in there.

Tomorrow I'm going to take the battery and have it load tested to make sure the static voltage measurement isn't misleading me.

I do appreciate all these suggestions though.
 

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Is it charging? both hot and cold (i.e. right after you start it and after a 30 min ride)?

My machine did this; it stopped charging once it was hot. While the bike was in service, the service tech noticed this. Checked, cleaned all connections - works now.. knock on wood.

Edit: *DOH* you do mention that it is charging.. but also when hot, check that.
 

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Mayor of Simpleton
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Discussion Starter #10
Load tested the battery today to be sure and it IS good.

Charging system is god too and I cleaned al the connections at the battery and starter and the regulator is hardwired in and fine as well.

Now I'm either going to pick up a couple stock used coils from Gotham, or looking into an upgrade from Dyna. However, their site lists by specs, not model applications. I'll start a new thread, but anyone know the necessary specs for these coils?
 

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coils

I would like to know about coils for the superbikes. I have 748 that I am building up
 

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Mayor of Simpleton
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Discussion Starter #13
Replaced the solenoid with a new one from Desmo Times. Didn't fix it.

Swapped both coils. Didn't fix it.

Guess I'm back to the beginning--and unless anyone else has a better idea, I think I'm going to be looking for a new starter.

Any brainstorms?
 

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I would set your TPS first as you say you didn't do it on
you own service as the meter had a bust lead.

brian.
 

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Replaced the solenoid with a new one from Desmo Times. Didn't fix it.

Swapped both coils. Didn't fix it.

Guess I'm back to the beginning--and unless anyone else has a better idea, I think I'm going to be looking for a new starter.

Any brainstorms?
Try another set of plugs (standard type). You say it's been getting progressively worse.. I know they are the fancy ones but maybe they've degraded.. is the Gap set wider then std plugs?

Just a thought.....
 
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