new to me 1984 ATC 125M

[Goatwrangler]

Hello all,

I'm new to 3 wheelers. A friend of mine who is on this forum finally talked me into getting one. Thanks Tyler...

I'm from Whitestown, Indiana and dont know jack when it comes to these trikes so I'm hoping to learn all I can.

The problem with my 84 is that it has spark (blue) but wont even try to hiccup when using starting fluid on it.
I dont have a manual on it so I'm not sure how to check the timing or anything like that. Does anyone have any ideas for me to start with ?

Thanks,

Jason

[GunsShooting]

Try a new spark plug. I have had plugs make a nice spark outside the engine, but fail to spark at all when installed in the engine.

Russ

[Goatwrangler]

Thx Russ,

I was thinking that but seemed to have good spark so I didnt think about a new one.
Ill replace it and report back.

Jason

[tripledog]

Just a tip, but carb cleaner is less likely to damage the piston rings and other internal engine components than starting fluid. Good luck, and welcome to the forum!

[bigman00]

some times the plug will not fire under compression. ever thought it looks good out of the cylinder. good luck with the 125 nice trike that was my first. look forward to seeing some pics

[Goatwrangler]

Thanks everyone and I was unaware carb cleaner could be a substitute for ether.

Jason

[kb0nly]

I buy a little spray bottle from the local hardware store, cleaning isle, get a little one for like a buck or less, fill with fresh gas. Better than ether or carb cleaner, etc. They are meant to run off gas, give it gas, thats my philosophy... You can set the bottle to stream to pump into the plug hole or set it to mist and spray into the back of the carb while your cranking.



So you have spark, nice blue spark by the sounds of it, but she won't fire... Since its a 125M, you got a battery in it and the electric start working? If so put your thumb over the plug hole and hit the start button and crank her over a bit. Does it have enough compression to pop your thumb off when your trying to keep it on the plug hole? You can use the recoil to do this also, but a lot easier to use the electric start when you got one hand occupied down on the plug hole.. LOL

If its got good spark and she won't start with some fresh gas squirted in, and she has good compression, then i would check timing.

Service and owners manual for that model are on my manuals website. Link below in my signature.

[Ghostv2]

Buy a new plug, clean the carb, see if itll run. If not, try pop starting it. Works for me usually with my 200s. I have a a semi rusty tank and it tends to make it run crappy if it sits for a little but pushing it up a hill and throwing it in gear usually seems to do the trick even when starting fluid and all that other stuff will not.

Thats the lazy way because i never want to take the carb off my 200s.

[Goatwrangler]

The electric starter does work. I can keep my thumb over the spark plug hole while cranking. I dont have a compression gauge to check it out though.

[GunsShooting]

WD-40 also works as starting fluid and it's much less volatile than other things.

Russ

[kb0nly]

If you can keep your thumb over the plug hole while cranking you got bigger issues. I would check to make sure the valves are moving. Pull the valve adjustment caps off and crank it over and see if the valves are moving. You might have a stuck exhaust valve, been there done that on a 125M. If your lucky you can get it freed up. The last one i worked on i sprayed PB Blaster around the valve guide and tapped on the rocker with a small block of wood and a rubber mallet a few times until it got free. But it could also be a broken valve spring on either the intake or exhaust but that doesn't seem to common.

If you crank it for a bit and pull the spark plug out is it wet? If the plug gets wet than at least the intake valve is opening, but it could even be stuck open.

Sounds like you need to diagnose the valves and if that takes you nowhere then its time to pull the motor and take the top end off it. You shouldn't be able to hold your thumb on the plug hole while cranking, the compression should pop it right off if the motor is healthy. You could try bump starting it as well, in case its a stuck ring that needs to free up.

When you crank it over is there any odd noises? Such as piston hitting a valve, etc.

[Goatwrangler]

Thx KB. I havent had much time to mess with it today. I did manage to throw a new spark plug in it and it backfires every now and then but thats it.

[kb0nly]

Hmm backfiring could mean a few things. I would still check the valves and timing, and pull the air cleaner tube off the carb, make sure the air cleaner isn't a rats nest starving it of intake air as well.

[Goatwrangler]

Will do. Air cleaner is off currently. I wasnt able to download a manual through your link. Probably something on my end but I'm not sure where to access the valves.

[kb0nly]

The link should take you to my website www.atcmanuals.info then click on the Manuals tab below the banner image. That page should show you a list of manuals to choose from. If thats not working let me know what your viewing it on, phone, computer, tablet, etc. So i can troubleshoot it in case there is a formatting issue.

Here is the direct link to the service manual.

http://kb0nly.info/ATC/index.php?dir...ice+Manual.pdf

The valves are accessed via the caps up on the head, looks like a big bolt head, those caps come off and you can see the rocker arm.