Tao Tao 125 starting issues

CorvZ061 · 03-20-2023, 11:13 PM

Pulled out my son's atv to get it started up and him riding again and immediately ran into an issue. Battery was dead, charged battery and engine struggles to spin over still. Battery dies very quickly. Battery is of unknown age so got a new battery. Engine still sounds like it's struggling to spin over when pressing the starter button and new battery dies pretty quickly. Pulled spark plug to check spark and noticed it's dry and black, almost sooty. Without plug in place engine spins freely. pulled Carb and disassembled and cleaned everything, reassembled and installed. went to start and get a click from starter solenoid, but nothing from the starter. removed the starter and found it was burned up, brush holder melted, one of the brushes floating. Ordered starter.

When new starter came I was able to get the engine running, for about 10 seconds. let off throttle and engine stalled, couldn't get it started again. Here's where I'm at now. I replaced the carb, had one that I bought last year and it's never been run. still nothing. When trying to start engine, if I give it any throttle at all it will not turn over, stops turning over as soon as I crack the throttle. If the idle speed screw is turned in too far, same thing. When it is spinning over it 'catches' for lack of a better word and stops spinning. I adjusted valves today, .006mm, no improvement. I have a new starter solenoid, haven't installed it. The CDI box was replaced last summer. I had a new coil and plug wire so installed that today as well.

Where do I go from here? I've done everything I know to do and it just will not run.

clash 168cc · 03-21-2023, 03:29 PM

Fresh non-eth gas. Water/sludge may be in fuel. New spark plug.

CorvZ061 · 03-21-2023, 05:53 PM

Quote:

Originally Posted by clash 168cc

Fresh non-eth gas. Water/sludge may be in fuel. New spark plug.

It has fresh gas in it, spark plug is a new ngk

**JerryHawk250** · 03-21-2023, 05:55 PM

Check for crack intake or leaks in vacuum lines.

krat · 03-21-2023, 08:41 PM

If it ran when you parked it for the winter it is a storage based issue.

Air-fuel-spark!

Check for all of them rather than just grinding away until the battery fries everything.

Putting fresh gas in the tank does not mean it is getting to the cylinder and a new battery does not guarantee you are getting spark.

Add to that the sluggish turnover sounds like you are starving for air.

After winter storage you might have a rat's nest in the air box, shellac inside the carb or a clogged fuel line.

Speaking of rats, they love the soy based insulation on chinabike wires.

You still have a number of simple things to check.

CorvZ061 · 03-21-2023, 09:00 PM

Quote:

Originally Posted by krat

If it ran when you parked it for the winter it is a storage based issue.

Air-fuel-spark!

Check for all of them rather than just grinding away until the battery fries everything.

Putting fresh gas in the tank does not mean it is getting to the cylinder and a new battery does not guarantee you are getting spark.

Add to that the sluggish turnover sounds like you are starving for air.

After winter storage you might have a rat's nest in the air box, shellac inside the carb or a clogged fuel line.

Speaking of rats, they love the soy based insulation on chinabike wires.

You still have a number of simple things to check.

I’ve checked spark, it’s there. Even with no air box at all, same thing. Fuel line was replaced, as was shut off valve. Fuel barely trickled out which led to the lines being replaced. New fuel filter installed at same time.

As far as I can tell the basic stuff has been checked. The struggling to turn over was an issue last year too, that’s not new but it would still start pretty easily. Now not at all.

clash 168cc · 03-21-2023, 10:15 PM

Can rarely be sheared flywheel key throwing off timing. Recheck valve gap is right with piston at top and check compression. Spray starting fluid. Shutting off while revving is no fuel or choke not closed (cold engine needs choke). Use your hand over carb to choke engine and also try while revving after it starts.

dirtbkr188 · 03-21-2023, 11:20 PM

Unless it is a typo in your first post, if you set the valves at .006mm, you have no valve clearance at all. The recommended settings for these engines is .002" (0.05mm) for intake and .003" (0.08mm) for the exhaust.

CorvZ061 · 03-22-2023, 07:17 AM

Quote:

Originally Posted by dirtbkr188

Unless it is a typo in your first post, if you set the valves at .006mm, you have no valve clearance at all. The recommended settings for these engines is .002" (0.05mm) for intake and .003" (0.08mm) for the exhaust.

You are correct. Typo on my part. Valves were adjusted with a piece of shim stock that measured at .003”.

david3921 · 03-22-2023, 05:34 PM

Quote:

Originally Posted by CorvZ061

You are correct. Typo on my part. Valves were adjusted with a piece of shim stock that measured at .003”.

Make sure that the valves were set on the correct stroke of the engine. Best way to check is that the arms are loose once it's set to TDC.

Also, this statement from above is pretty strange;
"When trying to start engine, if I give it any throttle at all it will not turn over, stops turning over as soon as I crack the throttle. If the idle speed screw is turned in too far, same thing."

Turning the throttle or adjusting the carb shouldn't have anything to do with cranking the motor.

Member that that these quads need the brake activated to start. I've had a rear brake wire that broke which kept the quad from starting but it turned over.

CorvZ061 · 03-22-2023, 06:06 PM

Quote:

Originally Posted by david3921

Make sure that the valves were set on the correct stroke of the engine. Best way to check is that the arms are loose once it's set to TDC.

Also, this statement from above is pretty strange;
"When trying to start engine, if I give it any throttle at all it will not turn over, stops turning over as soon as I crack the throttle. If the idle speed screw is turned in too far, same thing."

Turning the throttle or adjusting the carb shouldn't have anything to do with cranking the motor.

Member that that these quads need the brake activated to start. I've had a rear brake wire that broke which kept the quad from starting but it turned over.

I will record it. It’s very strange. But it seems if it’s getting too much air it won’t spin over.

CorvZ061 · 03-22-2023, 07:00 PM

Quote:

Originally Posted by david3921

Make sure that the valves were set on the correct stroke of the engine. Best way to check is that the arms are loose once it's set to TDC.

Also, this statement from above is pretty strange;
"When trying to start engine, if I give it any throttle at all it will not turn over, stops turning over as soon as I crack the throttle. If the idle speed screw is turned in too far, same thing."

Turning the throttle or adjusting the carb shouldn't have anything to do with cranking the motor.

Member that that these quads need the brake activated to start. I've had a rear brake wire that broke which kept the quad from starting but it turned over.

Here’s the video. As you can see it tried to start initially, but never does more than that. But also depress the throttle and it quits. Also does the same if the idle speed screw is turned in anymore. No idea where idle screw needs to be at right now, ut hasn’t run at all to be able to adjust anything.

david3921 · 03-22-2023, 07:38 PM

Never seen that before. Pretty weird. I think I would start there in the investigation. The throttle and front brakes are an assembly. Maybe by pushing the thumb throttle it's breaking the brake connection. Also, I see that it has a lanyard. Mine didn't come with one. Mine came with the rear one and the switch. There could be a possibility of corrosion in contacts of these safety features. I'm also curious about the small box on top. What's that for?

CorvZ061 · 03-22-2023, 07:46 PM

Quote:

Originally Posted by david3921

Never seen that before. Pretty weird. I think I would start there in the investigation. The throttle and front brakes are an assembly. Maybe by pushing the thumb throttle it's breaking the brake connection. Also, I see that it has a lanyard. Mine didn't come with one. Mine came with the rear one and the switch. There could be a possibility of corrosion in contacts of these safety features. I'm also curious about the small box on top. What's that for?

If we’re looking at the same box that’s the gear indicator. I don’t think it’s a safety cut out issue, I could be wrong on that. Reason I don’t think it’s a safety cut out is that it does the same with idle screw. If I turn it in even 1/2 turn further it sounds like it’s struggling to turn over. This is the main issue I’d like to fix, because if I can give it throttle while turning over I feel like I’d be able to get it to run when it ‘tries’ to start.

The lanyard switch seems to work? I’ll bypass it just to be sure.

I also jumped the starter solenoid today to make sure it’s not something dumb like a bad solenoid.

shad88 · 03-22-2023, 09:44 PM

Sounds like it may be the one way clutch on the flywheel not allowing the engine to crank over properly.

03-20-2023, 11:13 PM	#1
CorvZ061 Join Date: Mar 2023 Posts: 16	Tao Tao 125 starting issues Pulled out my son's atv to get it started up and him riding again and immediately ran into an issue. Battery was dead, charged battery and engine struggles to spin over still. Battery dies very quickly. Battery is of unknown age so got a new battery. Engine still sounds like it's struggling to spin over when pressing the starter button and new battery dies pretty quickly. Pulled spark plug to check spark and noticed it's dry and black, almost sooty. Without plug in place engine spins freely. pulled Carb and disassembled and cleaned everything, reassembled and installed. went to start and get a click from starter solenoid, but nothing from the starter. removed the starter and found it was burned up, brush holder melted, one of the brushes floating. Ordered starter. When new starter came I was able to get the engine running, for about 10 seconds. let off throttle and engine stalled, couldn't get it started again. Here's where I'm at now. I replaced the carb, had one that I bought last year and it's never been run. still nothing. When trying to start engine, if I give it any throttle at all it will not turn over, stops turning over as soon as I crack the throttle. If the idle speed screw is turned in too far, same thing. When it is spinning over it 'catches' for lack of a better word and stops spinning. I adjusted valves today, .006mm, no improvement. I have a new starter solenoid, haven't installed it. The CDI box was replaced last summer. I had a new coil and plug wire so installed that today as well. Where do I go from here? I've done everything I know to do and it just will not run.
	0

03-21-2023, 05:55 PM	#4
JerryHawk250 Moderator Join Date: Oct 2016 Location: Houma, La. Posts: 11,713	Check for crack intake or leaks in vacuum lines. __________________ 2024 Linhai 300 ATV 4x4 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S (Sold) 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel
	2

03-21-2023, 08:41 PM	#5
krat Join Date: Nov 2019 Location: KY Posts: 277	If it ran when you parked it for the winter it is a storage based issue. Air-fuel-spark! Check for all of them rather than just grinding away until the battery fries everything. Putting fresh gas in the tank does not mean it is getting to the cylinder and a new battery does not guarantee you are getting spark. Add to that the sluggish turnover sounds like you are starving for air. After winter storage you might have a rat's nest in the air box, shellac inside the carb or a clogged fuel line. Speaking of rats, they love the soy based insulation on chinabike wires. You still have a number of simple things to check. __________________ %90 of the Chinese motorbikes ever made are still on the road. The other %10 made it back home.
	0

03-22-2023, 07:38 PM	#13
david3921 Join Date: Feb 2009 Location: Michigan Posts: 1,043	Never seen that before. Pretty weird. I think I would start there in the investigation. The throttle and front brakes are an assembly. Maybe by pushing the thumb throttle it's breaking the brake connection. Also, I see that it has a lanyard. Mine didn't come with one. Mine came with the rear one and the switch. There could be a possibility of corrosion in contacts of these safety features. I'm also curious about the small box on top. What's that for? __________________ 2012 Kawasaki Versys 1984 Honda Magna V65 2016 Rhino 250 2016 Tao Tao 125D
	0

03-21-2023, 03:29 PM	#2
clash 168cc Join Date: Jul 2022 Posts: 94	Fresh non-eth gas. Water/sludge may be in fuel. New spark plug.
	0

03-21-2023, 10:15 PM	#7
clash 168cc Join Date: Jul 2022 Posts: 94	Can rarely be sheared flywheel key throwing off timing. Recheck valve gap is right with piston at top and check compression. Spray starting fluid. Shutting off while revving is no fuel or choke not closed (cold engine needs choke). Use your hand over carb to choke engine and also try while revving after it starts.
	0

03-21-2023, 11:20 PM	#8
dirtbkr188 Join Date: Aug 2009 Posts: 574	Unless it is a typo in your first post, if you set the valves at .006mm, you have no valve clearance at all. The recommended settings for these engines is .002" (0.05mm) for intake and .003" (0.08mm) for the exhaust.
	0

03-22-2023, 09:44 PM	#15
shad88 Join Date: Mar 2021 Location: Boston Posts: 21	Sounds like it may be the one way clutch on the flywheel not allowing the engine to crank over properly.
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