1985 Honda ATC 125M won't start

[PYang004]

Trying to get an old trike running. It's been sitting for 2-3 years. Before then it was running just fine. It was parked and forgotten.

First off the engine cycled like 3 times then locked up. I removed the head and cylinder block and cleaned everything. The top of the piston and cylinder were all gummed up. That's why the engine wouldn't cycle. Lubed everything with 4 cycle motor oil when I reassemble the engine. Made sure the timing was correct as well. Piston on top dead center and the cam gear marks matched. I couldn't find the markings in the CDI like what was shown in the manual, so I put that back the way I remembered. I fully cleaned the carburetor and made sure all passage ways were cleared.

With the battery hooked up the headlights work and the start button works. I've replace the spark plug and tested it for spark. I've tried with the choke slightly open and fully opened. Tried pumping the throttle lever while cranking. Tried start button crank and pull string. Tried without the intake plumbing and with it. I can hear and feel the throttle body suck air in and the exhaust pop out. There is a male fitting inside the throttle body on the intake side of the throttle body plate and spits out fuel. The spray looks to be the fuel source into the combustion chamber as the air gets sucked in. I was told to check to see if the spark plug is wet with fuel, but it doesn't seem like much fuel can get down into the combustion chamber.

I know I'm getting spark and the fuel flows freely through the carburetor. I'm not sure if fuel is getting into combustion chamber and I'm not sure if the CDI timing is correct. What else can I check?

[jaredc00]

CDI timing is just lining up the timing mark on the timing chain with top dead center, which you've done. I don't know of any other timing. You need to check compression and valve clearance. If that looks good, double check spark, it might just be too weak due to a worn ignition coil or bad connection or something like that. Anyway get back to us when you've checked valves and compression.

[PYang004]

Can do. Might be awhile though. I don't have a lot time on my hands. This isn't top priority, so I work on it we I can. I know the valves are off, I just guessimated there because I don't have the feeler gauge. What is the compression suppose to be around? The spark did look weak by the way, compared to a car. How is the spark suppose to look compared to a car?

Thanks for the info by the way.

[PYang004]

I replaced the ignition coil and the spark looks the same.

The valves are correctly adjusted. .003 inches / .07 mm

I doubled clean the carburetor removing all screws, jets, and valves. Adjusted the pilot screw (small pin at the end of the screw) to 1.5 turns from full close. Adjusted the throttle stop screw (larger pin at the end of the screw) to 2 turns from full close (can't adjust this perfectly until the engine runs).

I couldn't do a compression test. I can't seem to locate my compression test tool at the moment.

I also tried to take the spark arrestor off to clean it, but it seems to be rusted on there. I got the lock bolt off. Doesn't seem to have blockage thought, since I can feel and hear the air pop out of it.

Another thing I notice when adjusting the valves. Can I have installed the cam shaft backwards? At top dead center the valve arms would not move. I slowly pulled the pull string and watched the exhaust valve open and close, then the intake valve open and close, then gave it another 1/4 turn. This made the the valves loosen up and I was able to adjust them. But the engine was not at the top dead center marking. More like the complete opposite side of the TDC mark.
***There's no way I installed the cam shaft in backwards. The holes on the cam shaft that bolts up to the cam gear only fits one way. I set the crank to TDC and lined up the timing chain and cam gear to the mark on the head casing. The mark on the cam gear is only on one side.

Anyways I have to wait until I have some more free time to look into the cam shaft install more closely.

[clmeue37]

I'm sure you are already aware that the valves must be adjusted when the piston is at TDC. It almost sounds like you may have the timing off 180. Let me know if I'm wrong on this one...

[MARTIN1]

Patience and persistence pays off

[PYang004]

So an update on this.

- Timing has be rechecked and the cam was reversed 180. Weird because I clearly remembered lining up the cam gear mark to the mark on the head. Oh well, I did it again so the timing should be dead on.
* Still no start.

- Triple check spark again and it's still good.

- Double checked the CDI unit connected to the cam shaft and all the markings line up and are correct.

** Now here's the only thing I have left that I can think of. Compression. I still can't find my compression tool anywhere. Gonna see if I can barrow one from someone. I'm pretty sure I don't have enough compression though. When I place my finger over the spark plug hole there's not enough pressure to blow my finger off. The spark plug is also cover with oil, so I can't tell if fuel is getting into the compression chamber. When I open the engine to clean the gunked out piston, there was a lot of carbon build up around the piston cylinder. It seems those area were worn down and filled with carbon residue. So once I cleaned it, the compression is now leaking into the crank. It seems that's also the cause that the oil is making it's way up on the spark plug.

- Can anyone confirm a quick compression test using the finger method?

- If the details above are correct... Would all I need is a new set of piston rings? Everything inside looks to be in really good condition.

Thanks.

[sweetip2000]

I know this might sound stupid but are you using fresh fuel ?
And is there any rust inside the gas tank ?
Is the gas cap vented and breathing.

[PYang004]

I know this might sound stupid but are you using fresh fuel ?
And is there any rust inside the gas tank ?
Is the gas cap vented and breathing.

Fuel is fresh. Tank was emptied when I got it. No rust inside at all. Cleaned out the dust with fresh fuel and filled it up half way. Fuel flows freely out of both fuel hoses. The gas cap does not seal tightly. The rubber seal is dried up and cracked in 2 pieces. It's still in place under the gas cap.

Keep throwing ideas to me. I just want to get this motor running before I get into the rest of the restore.

Thanks.

[clmeue37]

Did you adjust the valves again after resetting the timing?

[Jason125m]

Did you check the ring gap before reassembly? Was the cylinder nice and smooth? You said you had it apart, did you install new gaskets?

[PYang004]

Just installed new piston rings... such a pain and all new gaskets. Doubled checked everything listed above on the way out. Placing my finger over the spark plug hole I am getting more pressure than before. I don't have the correct size compression tester to get a reading. The motor still won't start up. Ugh!

How is the fuel delivered into the combustion chamber? Does it just get sucked in with the air from the throttle body? How much fuel gets down there after a few cranks. I'm thinking it might still be the carburetor, but I don't want to buy a kit or a new unit, until I'm pretty sure. The piston rings were such a pain.