T500 that stops running when hot,

[LexPaul]

Any thoughts would be appreciated. My T500 stops running when it gets hot.

Runs great for 20 or 30 minutes and then it just dies. Seems like both cylinders die. It does this bogggg down thing and there you are, God and a T500 on the side of the road and the bike won't move.. If I wait 30 minutes or so, the bike will fire back up, but as soon as it gets hot, motor stops running.

Carbs have been rebuilt, top end rebuilt, new battery this week

I am running B7HS plugs and will check the caps for compatibility this week. The caps are new, but I am not sure what model they are, because the vintage bike shop put them on.

I have newtronic ignition. I went over the check sheet and the switch box is working and the rotor eyes are working as well. My spark seems very weak, almost cannot see and at some rotor passes I could not see spark at all. When the bike last stopped, my friend and I hooked up plugs on top of motor, grounded them and kicked motor over to look for spark. There was very little spark and maybe no spark most of the times, when there should have been spark.

Can anyone suggest how I might check the coils, caps, and condenser, that they are working correct when bike is hot. Any suggestions would be appreciated. Take care and pray for my T500,

[jabcb]

The Newtronic ignition eliminated the condensers so that can't be the problem.

Best bet would be to replace the coils & caps with new aftermarket parts.

Rex Caunt sells coils that fit the stock coil brackets.
They are often available via eBay but are cheaper if you order them directly from him.
http://rexcauntracing.com/pages/htcoils.html
You need the battery-type HT coils with mounting dimension of 80mm.
He sells coils with primary resistance of around 2 & 4 ohms. You need the ones with approx. 4 ohms primary resistance.

For plug + cap combos, use non-resistor plugs with resistor caps, or resistor plugs with non-resistor caps.

For standard non-resistor plugs: NGK B7HS plugs + NGK LB05F resistor caps.
For fine-wire resistor plugs: NGK B7HIX plugs + NGK LZFH caps.

For fine-wire non-resistor plugs: NGK B7HV or B7HVX plugs with NGK LB05F resistor caps.
These plugs are discontinued but are still available via eBay & some other sources.

[castle1925]

No need to replace coils until you have determined they are bad. That's an expensive recommendation. Since the bike bogs down rather than cuts out on one side, it's unlikely both coils would die at the same temperature.

Does the engine crank easily after the bogging down? If so, this would eliminate soft seizing from piston over-expansion.

Can you tell if the fuel lines are still full? Could be a line is loose or the petcock is partially clogged.

[LexPaul]

The engine does crank easy, even after it has stopped, fuel lines are flowing free, petcock was cleaned not 30 days ago.

[titan performance]

Sounds electrical, but not creating a vaccuum in the petrol tank are you?

[LexPaul]

I am not following your question, please explain. I can see fuel coming into my fuel lines, if that is what you are asking. Thanks

Sounds electrical, but not creating a vaccuum in the petrol tank are you?

[jabcb]

There is a small hole in the petcock that lets air into the tank. If its plugged up, then fuel will not flow out as it should.

I agree that its logical to determine if the coils are bad.
Determining if the coils have heat related issues is problematic. Replacing them is an easy fix that I can handle.
So I'd replace them without testing them even though it might be an unnecessary expense.
(I agree that my logic is somewhat distorted by having to many bikes.)

[Craig380]

When I had an ignition coil go bad on my triple, the engine would die instantly, as if I'd hit the kill switch.

Can you remember if any electrics work on the bike with ignition ON, immediately after the motor dies? If you get no (or very weak) lights / horn etc, it's fairly certain that the coils' primary windings are being shorted to earth, which takes all the juice from the battery.

When the coils cool down, the primary windings stop shorting and everything works as normal again.

[LexPaul]

The Newtronic ignition eliminated the condensers so that can't be the problem.

Best bet would be to replace the coils & caps with new aftermarket parts.

Rex Caunt sells coils that fit the stock coil brackets.
They are often available via eBay but are cheaper if you order them directly from him.
http://rexcauntracing.com/pages/htcoils.html
You need the battery-type HT coils with mounting dimension of 80mm.
He sells coils with primary resistance of around 2 & 4 ohms. You need the ones with approx. 4 ohms primary resistance.

For plug + cap combos, use non-resistor plugs with resistor caps, or resistor plugs with non-resistor caps.

For standard non-resistor plugs: NGK B7HS plugs + NGK LB05F resistor caps.
For fine-wire resistor plugs: NGK B7HIX plugs + NGK LZFH caps.

For fine-wire non-resistor plugs: NGK B7HV or B7HVX plugs with NGK LB05F resistor caps.
These plugs are discontinued but are still available via eBay & some other sources.

Question, does the rectifier that we see under the seat have anything to do with ignition? Thanks

[LexPaul]

When I had an ignition coil go bad on my triple, the engine would die instantly, as if I'd hit the kill switch.

Can you remember if any electrics work on the bike with ignition ON, immediately after the motor dies? If you get no (or very weak) lights / horn etc, it's fairly certain that the coils' primary windings are being shorted to earth, which takes all the juice from the battery.

When the coils cool down, the primary windings stop shorting and everything works as normal again.

Yes, the electrics continue to work we even after the bike dies..

[Vintageman]

+1 on Coils or Newtronics

Coils are very difficult to trouble shoot when intermittent. my experience with Rotax engines in sleds also used in UltraLight aircraft,.. coils have low/finite life time.

Do you have a spare set you can try if you don't want to buy others?

Else I would suspect the Newtronic.

Maybe take a hair dryer and heat thing ups and see if you can accelerate failure.

Those coils don't look too expensive considering how much I spend $$ in total
Are those or similar coils available in USA? Do they have a higher voltage output?

[LexPaul]

A couple of very good points, we will look at all this Friday and I will post an update soon. Thanks

[tz375]

Sounds like it is running out of fuel. Next time it dies, open the fuel filler cap and see if that fixes the problem within a minute or so.

There is a pin hole in the filler cap that allows air to enter the tanks as fuel drains out. If that is blocked the tank creates a partial vacuum and fuel stops flowing.

[jabcb]

Those coils don't look too expensive considering how much I spend $$ in total
Are those or similar coils available in USA? Do they have a higher voltage output?

Haven't seen any specs, but from my experience I'd say they are better than stock.
Definitely not in the same league as Dyna coils. But I haven't found any high performance coils that fit the stock coil brackets (mounting dimension of 80mm).

Ordering them from the US is no problem -- just takes a little longer to get here.
Vaguely remember seeing another source of 80mm coils, but it might just be another retailer of the same coils.

[titan performance]

Was about to explain my earlier post, but TZ has done it for me.
If the breather hole is blocked, it would take some time to create sufficient vacuum to restrict fuel flow. Left for a while the pressure will equalize and fuel flow again. When the engine stops, pull a fuel pipe quickly and see if you have fuel flowing.

I have had this issue with a car...never a bike, but the symptoms match.