TT ATA-250 runs like crap

Skripo · 08-13-2009, 12:36 PM

I changed the carb and spark plug on my ATA-250 sometime ago and it ran like a champ but I always had a near dead battery problem, so charging seemed problematic. Luckily it started right up so it was not an issue.

All of a sudden it started dying and sometimes backfiring. It would not start unless full choke was applied. When it would start it would run fine for a few seconds then die or go great then die, as if the spark was weak or absent.

I suspect the stator and/or CDI, does this sound likely? How do I test the CDI and Stator? Has there been common electrical issues I should look at?

Weldangrind · 08-13-2009, 12:48 PM

My vote is that there's something trapped in a carb passage. Full choke is my clue; it sounds like a jet is blocked, causing an overly-lean condition, hence the back firing.

TurboT · 08-13-2009, 01:38 PM

Quote:

Originally Posted by Weldangrind

My vote is that there's something trapped in a carb passage. Full choke is my clue; it sounds like a jet is blocked, causing an overly-lean condition, hence the back firing.

If you're using the stock air filter you might have a mouse in there, as I think it might be able to slip through the gaps in the filter. 8O

eflyersteve · 08-13-2009, 03:43 PM

Yeah, sounds like fuel problem. The clues as W-N-G pointed out. If it were electrical you'd likely get nothing. Fuel is seeping by somehow where it should be flowing.

Something as simple as a plugged gas tank vent. Does it happen more quickly the fuller the gas tank? There's more space to create a vacuum when there is less fuel in the tank so it takes longer to run out of fuel.

If you open the carburetor bowl drain, does the fuel run out in a good stream? If so, the blockage is likely in a jet or passage after the bowl circuit.

Good luck on the fix. Be sure to let us know what the fix is so we can all learn from it.

Skripo · 08-13-2009, 11:02 PM

Great tips guys and it seemed like it started right after I filled the tank. Will update you soon. New mikuni carb and large air filter by the way.

Skripo · 08-15-2009, 07:49 AM

You guys are geniuses. I installed a new breather and it didn't breathe, thereby creating a vacuum in the tank. Runs like a a top again!

Thanks guys!

Weldangrind · 08-15-2009, 12:01 PM

What sort of new breather did you install? Was it a fuel cap breather? Pics? It would be great if other members could benefit from your experience.

Skripo · 08-19-2009, 09:38 PM

It was a replacement stock one.

Sorry about the delay in responding, renovations are killing me.

Weldangrind · 08-19-2009, 10:00 PM

I'm in renovation hell myself.

Was it the fuel cap that was the problem?

Skripo · 08-20-2009, 04:02 PM

No just the breather itself. The old one fell off, as do most parts on these machines, so I bought a new one. It was completely blocked and caused a vacuum to form in the tank as the fuel was used up.

Weldangrind · 08-20-2009, 09:22 PM

Got a pic? I'm drawing a blank.

08-13-2009, 12:36 PM	#1
Skripo Join Date: Jun 2009 Posts: 39	TT ATA-250 runs like crap I changed the carb and spark plug on my ATA-250 sometime ago and it ran like a champ but I always had a near dead battery problem, so charging seemed problematic. Luckily it started right up so it was not an issue. All of a sudden it started dying and sometimes backfiring. It would not start unless full choke was applied. When it would start it would run fine for a few seconds then die or go great then die, as if the spark was weak or absent. I suspect the stator and/or CDI, does this sound likely? How do I test the CDI and Stator? Has there been common electrical issues I should look at?
	0

08-13-2009, 12:48 PM	#2
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	My vote is that there's something trapped in a carb passage. Full choke is my clue; it sounds like a jet is blocked, causing an overly-lean condition, hence the back firing. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

08-15-2009, 12:01 PM	#7
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	What sort of new breather did you install? Was it a fuel cap breather? Pics? It would be great if other members could benefit from your experience. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

08-19-2009, 10:00 PM	#9
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	I'm in renovation hell myself. Was it the fuel cap that was the problem? __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

08-20-2009, 09:22 PM	#11
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	Got a pic? I'm drawing a blank. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

08-13-2009, 03:43 PM	#4
eflyersteve Join Date: Jul 2009 Location: Oklahoma Posts: 44	Yeah, sounds like fuel problem. The clues as W-N-G pointed out. If it were electrical you'd likely get nothing. Fuel is seeping by somehow where it should be flowing. Something as simple as a plugged gas tank vent. Does it happen more quickly the fuller the gas tank? There's more space to create a vacuum when there is less fuel in the tank so it takes longer to run out of fuel. If you open the carburetor bowl drain, does the fuel run out in a good stream? If so, the blockage is likely in a jet or passage after the bowl circuit. Good luck on the fix. Be sure to let us know what the fix is so we can all learn from it.
	0

08-13-2009, 11:02 PM	#5
Skripo Join Date: Jun 2009 Posts: 39	Great tips guys and it seemed like it started right after I filled the tank. Will update you soon. New mikuni carb and large air filter by the way.
	0

08-15-2009, 07:49 AM	#6
Skripo Join Date: Jun 2009 Posts: 39	You guys are geniuses. I installed a new breather and it didn't breathe, thereby creating a vacuum in the tank. Runs like a a top again! Thanks guys!
	0

08-19-2009, 09:38 PM	#8
Skripo Join Date: Jun 2009 Posts: 39	It was a replacement stock one. Sorry about the delay in responding, renovations are killing me.
	0

08-20-2009, 04:02 PM	#10
Skripo Join Date: Jun 2009 Posts: 39	No just the breather itself. The old one fell off, as do most parts on these machines, so I bought a new one. It was completely blocked and caused a vacuum to form in the tank as the fuel was used up.
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