After running fine for a few months my kids Tao Tao 110cc won't start. Battery is fine, engine turns. I confirmed that the spark plug is clean and sparking. I tried squirting some gas directly into the carb and also down the intake. NOTHING. Cranking sounds mostly free spinning. No combustion at all. I put a 14mm socket to the flywheel bolt and while it mostly spins easily, it does seem to have some resistance (compression?) at certain points, but not much. At it's last heathy running moment my kid was riding it in the back yard.

Ok, so I finally called in a favor and asked a Auto Transmission mechanic friend of mine to take a look. He thinks it's the timing chain. But he's not positive and not sure if repair is worth the cost/effort.

Question: It a timing chain a DIY repair? Any hints on how to do it? Where can I buy a replacement timing chain? After install is it easy to set the timing right?

Any comments would be appreciated !

 

I haven't really heard of timing chain issues with these engines. I'd test for compression before proceeding further. If no/low compression I'd suspect a valve seating issue first (bent valve stem, valve stuck open).

Joel

 

I would check the valves for proper clearance..

 

Thanks Joel. I was able to look at the timing chain and with spinning the crank shaft manually it does indeed look perfectly aok.

How do I get in to look at value seating as you suggested? I was able to remove the valve cover on the cylinder head. I do see the rocker arms moving as expected when spinning the crank shaft. To remove the cylinder head do I have to totally remove the engine from the frame?

 

YouTube - How to Adjust Honda 50/70 cc Valves

 

I did the valve adjustment yesterday. Pretty easy effort. .003-.004

Unfortunately the engine will not not start, and turns pretty freely on manual crank and starting crank. Nothing that sounds like combustion.

Here's what I've tried and eliminated:
- Valves. Inspected, adjusted, and they rock as expected on manual crank.
- Spark. Plug is very clean and a nice visible live spark can be seen when removed and starting crank.
- Gas. Tried everything, including gas in spark plug hole, and carb removal and gas directly in.

Question: I guess it must be some a failure at the either the values themselves or the piston rings. Either of these inspections I assume requires an engine removal and cylinder head removal. Is this my next step?

 

Yes that is next. If you dont see something obvious with the valves when you get the head off.. The cylinder and piston will need to come off to check the ring gap.

 

Considering that we spent maybe $500-$600 for the Chinese quad delivered, is this maybe the right time to it quits and mercifully end the misery? Am I just having a hard time saying goodbye? The quad has lived 6 months, lots of good hours in our 1 acre backyard with my 15yr old and plenty of his friends.

 

[QUOTE=JohnReam;2927694] is this maybe the right time to it quits and mercifully end the misery? /QUOTE]



Thanks for the laugh!! I would try to fix it.. parts are cheap enough..

 

Have you verified that the ****** cord plug on the rear of it is plugged in?