1997 TXT does not run properly

[ScottD1]

I recently bought this cart and the previous owner said it didn't run right after warming up. I have found it to have issues most of the time from hard start to low power to stumbling and backfiring.

PO put in a new CDI and thought maybe it needed a coil. I put in a coil and that didn't change anything. Checked spark with spark tester before and after no change.

So far I have done the following.

Insured gas is good,

Checked fuel pump was pumping

Removed and cleaned carb

Adjusted valves

Compression check 135 in one, 145 in the other. Added oil and retested, both went to 175.

Pulled timing belt cover and checked timing mark alignment.

Plugs look normal not oil or fuel soaked not overly lean.

Running out of ideas. Anyone have other things to check? A guy who I think is knowledgable on another forum suggested its time to rebuild or replace, thoughts? It has a rattle noise at times that I can't identify, it sounds almost like pinging from ignition timing but on a small motor like this I suppose it could be piston slap. It is audible on the video I'm including.

youtube.com/watch?v=5pgBsGRZ6uw


Thanks in advance.

[Shepard]

Is timing set properly? All the noise could be ignition knock. Would make it hard to start when hot. May not have a lot of power.

[ScottD1]

Originally Posted by Shepard

Is timing set properly? All the noise could be ignition knock. Would make it hard to start when hot. May not have a lot of power.

When you say timing I assume you mean valve timing? As far as I know the ignition timing is not adjustable. I'm brand new at this so I could be wrong. The valve timing is correct as far as I can tell by looking at the timing marks.

Thanks

[Shepard]

Originally Posted by ScottD1

When you say timing I assume you mean valve timing? As far as I know the ignition timing is not adjustable. I'm brand new at this so I could be wrong. The valve timing is correct as far as I can tell by looking at the timing marks.

Thanks

OK - if it's not adjustable then check the trigger unit under the flywheel with an ohm meter. Not hooked to anything check the resistance across the 2 wires of the pulse coil. Maybe 4-500 ohms, then check, one probe in the harness plug - the other probe to the engine - your checking to see if the coil has an internal ground. Then wire the probes to the trigger coil so you can spin the engine over and see how much voltage the trigger produces. In the moocycle world the voltage can be up 2-3 volts.

[ScottD1]

I did check the resistance it showed 21 Ohms I will do the other tests tomorrow. Thanks!

[Johnmaster]

if the flywheel is keyed to the crankshaft and it sheared, it would throw timing off (backfiring could cause this). If you can get it to run, checking timing with a light will confirm if its timed correctly or not.

[trig123]

In my 21 years working on these engines I never seen a flywheel key sheared. I think you might be wasting your time on this. That engine has a knock from what I heard on YouTube.
If you got spark with a spark tester then there is nothing wrong with your ignition .
I really think the engine is going to have to be removed and find that knock before it's too late. You are working behind someone and you really don't know what all has been done to the engine.

They are not hard engines to remove and rebuild. They are a little high on the parts though, at least from the source I had.

The other thing I might suggest if you don't want to tear it down right now is order a new carburetor . Money well spent if you do rebuild it.

I bought one last month from ebay for $20 and it runs like a top. I also rebuilt my engine and installed new intake valves. My 9hp will start up without having to choke it and it starts quick. Lots of power and no engine noise. I got 150 pounds compression on both cylinders. It should move up after these rings seat.

Just some thoughts from someone who has been doing mechanic for close to 55 years.

[Cartmaster]

I would try borrowing a known to be good igniter (preferably genuine ezgo) sound to me like a random spark causing the low power and knocking/pinging noises. If the noise were mechanical, it would be regular all the time the pedal is down and under any load.

Usual supects are valves, dirty carb, poor fuel pump, ignition component failure.

the ignition parts you have already replaced, were they genuine or imported? Imported (chinese) electrical parts would be the first place i would expect trouble. If the Igniter were replaced by the previous owner flipping the cart, my suspicion is that he used cheap chinese parts.

so first port of call is find a genuine igniter and coil and start over.

Only other thing easy to check is the valves. I know you say you have checked them, but look at the two inner adjusters and see how much thread is showing above the locknuts compared to the outer two. If more that a couple of turns, you will need to look at replacing the inlet valves.

[trig123]

Cartmaster, I would agree with you except for one thing. Where does EZGO get their ignition parts? From what I have seen no matter what brand you get it comes from China.
I rebuilt my Nissan Xterra with the 3.3 engine 6 years ago. I ordered parts from the local NAPA store here and told them I wanted only OEM rod bearing. Got the inserts and on the box it said Japan. Written on rod bearing it said China.

I do understand it could be a bad ignitor but he said the previous owner was having problems. I didn't see where he mentioned it having the knock though.

Maybe the poster could tell us if it was knocking when he got it from other person.
I listened to that knock on his YouTube video. To me that didn't sound like pinging but I could be wrong.

[Cartmaster]

Trig, even you with around 55 years experience can tell if a part is genuine or a knock off by price alone and even then the actual quality of finish is usually a good tell. I did not state it had to be Made in USA, just from the OEM factory, which could be in China, or anywhere else in the world. I have dealt with a lot of factories in china and can tell you, some are genuine oem manufacturers for The States and the uk, but there are many more producing knock offs that only just make the grade.
Turn your laptop over and i assume it is a well known brand like mine and look where it was made. Most likely China. BUT and it is a big BUT, it is an OEM quality controlled factory. OEM producers usually have a full time Quality control officer living in china and working in the factory. That is the subtle difference.

I still think that maybe the previous owner has fitted knock off parts, as OEM are so hard to find and also did it to save money.