How to adjust valves on 84 125cc honda atc

[rockd]

I just bought a 84 125cc altought the engine runs it is very noisy...as if there were a knock, only it sounds like it is coming from the head and not the bottom end. I have used a mechanic stetoscope in order to narrow it down.

As anyone ever been thru similar?

[Woodsrider]

I just checked mine this afternoon...the intake valve is a real pita...not much room to get your fingers in there. I'm guessing that the proper feeler gauge(with the little bend in the end) would make this a lot easier...I just have the regular straight ones. I would consider removing the bolts in the front engine mount (and a few other necessary things)and letting the engine swing down on the rear mount bolt...the next time....just so I could get real clear access to be sure of doing a good job.

Your noise could be a valve or worn cam chain.....loose wrist pin???....lots of possibilities(there are people here that could probably tell you what it is just by listening to it). If you need any parts, PM me....I'm in the middle of fixing one up for my nephew and I have 2 other machines that are parts donors...

[tri again]

I just bought a 84 125cc altought the engine runs it is very noisy...as if there were a knock, only it sounds like it is coming from the head and not the bottom end. I have used a mechanic stetoscope in order to narrow it down.

As anyone ever been thru similar?

yupp, just last week and would've bet the farm I had a rod knock.

listen to the engine pulses. are they the SAME as the knock? or every Other pulse.

anyway, I would take the valve covers off one at a time and just press down on the rocker with a gloved hand while it is running to see if it changes the knocking...even if you cant adjust them.
Even safer if you're attached to your fingers, is to press on the rocker with a piece of wood....anything to take out or reduce the rocker lash.


you'll at least be able to sleep.

They will throw oil a little (hopefully) but we're talking aboout peace of mind here.

My intake valve had apparently adjusted by goober over to gomers shop and he used a shovel since he ad no gauges,

I would have bet anything it was a rod or worse.

Valve adjust got rid of all of the noise.

[peter250r]

ive got an 84 125m and ive had a look at the valve rockers to see how to adjust them, not that they really needed it. just checkin. you'll need a special attachment to loosen the rocker adjusting screw its not one that you can do with a screw driver, its got a lock nut. put the correct feeler gauge in the gap then tighten the screw against the feeler gauge. enough so you can slide it out. but before sliding it out tighten the locknut. i haven't actually tried this, you may have to drop the engine down for this.

[Woodsrider]

[QUOTE=peter250r;877739 you'll need a special attachment to loosen the rocker adjusting screw its not one that you can do with a screw driver[/QUOTE]

The head of a #2 Robertson(square drive) screw fits perfectly. I made a tool by driving a short screw into a wooden dowel.

[rockd]

Thank you all for responding, i decided to take a closer look, I started taking the engine apart to look at the timing chain...turns out one of the bottom gear is pretty worn out and may be the source of the noise.

Does anyone know where I can get engine specs? tolerance, torque settings etc...

[peter250r]

http://i257.photobucket.com/albums/hh211/cbf900/enginespecs1.jpg
http://i257.photobucket.com/albums/hh211/cbf900/enginespecs2.jpg
http://i257.photobucket.com/albums/hh211/cbf900/enginespecs3.jpg
http://i257.photobucket.com/albums/hh211/cbf900/enginespecs4.jpg
http://i257.photobucket.com/albums/hh211/cbf900/enginetorquespecs.jpg