New too the site and I bring Questions.

[keveldevel]

Hello nice place here, I recently picked up an old 1985 Honda 125M. It would fire with starting fluid but not run, no brakes and had 3 flats when I got it. I Ordered and installed breaks, completely rebuilt the carb, and installed tubes in the tires as they still had awesome tread on them.:)

So now I have been trying to get it running strong and im having trouble. I think my problem is a carb problem but not sure what. I have set the pilot screw an then backed it out 1.5 turns as stated in the manual I have the idle set at a nice sounding idle ( slow rpm but runs on choke) Now heres the problem I can get it to run with the choke on but if I turn the choke off it will stall out, if I try to give it some throttle choke/NO choke it dies immediately. IV been adjusting the crap out of the pilot and idle screws but no luck it does it no matter what I do.:wondering

anyone have any idea? Id like to take this up to my property and use it there as a point a to point b on the property.

Thanks in advance, anything else you need to know just ask ill get the info asap.
Thanks for letting me join 3WheelerWorld:beer

[belly]

Welcome to the site. It sounds like your pilot jet is clogged. Go through and clean the carb one more time. Did you replace the fuel filter if it had one? flush the tank? If it doesn't have a fuel filter, put one on. As far as adjusting the air fuel screw, i usually revved the engine to 2K rpm and turned in the screw. once it starts to stumble, turn it back just a little bit. If starting at 1 1/2 turn out doesn't help, start at 2 turns out. Everyone has their own method for tuning. search for "carb adjustment" or "carb tuning". Tons of threads and lots of great info. Good luck and keep patient!

[barnett468]

Hello keveldevel.


As belly said your pilot is most likely plugged.

How old is gas?

Did you add NEW gas to OLD gas that was left in the tank?

Any RUST in the tank?


This is what I would do.


Drain gas into narrow glass via drain screw on bottom of float bowl, what color is gas clear or apple juice color, any sediment in bottom of glass, any small clear water bubble in bottom of glass?

Remove both jets, find a drill bit slightly smaller than the jets. Using moderate pressure slide jet up and down bit rotating jet a little at a time for 1 full revolution then clean with carb cleaner. This will removed any hard non dissolvable particles.

Spray carb cleaner into pilot jet hole and make sure you see it come out inside the carb bore.

Check float level per manual, it may be way too low.

Reinstall jets, put carb on bike test again.

If it is better but still lean [needs choke to run] raise the needle in the slide ALL the way by LOWERING the clip. Don’t lose it! Retest.

Tell us gas test results, original needle position, carb cleaning results, performance results.

[keveldevel]

Belly, barnett468 Thanks for pointing me in a direction. I was just standing there wondering what I did wrong.

The gas is fresh.

The carb has a fuel filter in it, I could not remove it when I had the carb off. I tried pulling and turning like it was threaded but it wouldnt budge. I did spray it out really good with carb cleaner and blew with air. I also installed a inline fuel filter BEFORE the carb. ( there is small rust spots in the tank, not bad but not great) So I added the filter to keep the carb cleaner.

When I first installed the carb fuel dumped right out the bottom of the carb, so I took the float and adjusted it, reinstalled the whole thing and she didnt leak and would fire up and run with choke on.
So maybe I adjusted the float to much or something? I really dont know. rebuilt a few carbs in my days but never used an adjustable float before.

Should I put the old nonadjustable float back in? it looked fine, just discolored. and of course if I due that Ill need to use the old needle because the are differant in the way the hang on the float.

Anyway thanks again for the help/ guidance. I will try out these suggestions tonight or tmr. Im heading out of town right now for a few hr. have a good one fellas.

Off the top of my head the needle is on the second slot from the bottom, I didnt touch that while working. wasnt sure what that part did exactly lol and the new needle was shorter in comparison to the original, so I just left the old one in as it looked fine.

Ill let you know what happens in a day or so.

[JasonB]

sounds like these guys have you covered on chasing down the issues, all I can say is Welcome!

[barnett468]

Hello


If it only runs with the choke ON or runs best with it the pilot circuit is lean [plugged or too small of a pilot jet] and/or LOW float level.

Remove both jets, find a drill bit slightly smaller than the jets. Using moderate pressure slide jet up and down bit rotating jet a little at a time for 1 full revolution then clean with carb cleaner. This will removed any hard non dissolvable particles.

Spray carb cleaner into pilot jet hole and make sure you see it come out inside the carb bore.

Check float level per manual, it may be way too low.



Gas level test drawing pg 4-4. Level should be around 1/8” or slightly greater below the bottom of the carb body where it meets the float bowl.

http://www.oscarmayer.net/atc/manuals/Yamaha/ytm200_yamaha_servicemanual.pdf

[danbur55]

Might check for vacuum leaks. I've chased float levels up and down only to discover a small leak on a couple of four wheelers of mine. Good luck

[keveldevel]

Well Iv gone from patient to pissed over the last few days lol.

I have had the carb off about 20 times changed the floats out, messed with float levels, cleaned and re cleaned the carb several. I raised the needle all the way, and its still the same. ( runs on choke, shuts off after 2 mins or so, I can get it restarted if I give it full throttle but it dies quickly after)

Basically it runs then shuts down in a few. only on choke.

the original needle was set at the 2nd rung from the top, i moved it to the bottom rung and tried and no change really.

Im stump of why it wont stay running.

Is it possible that its something electrical?

thanks again

[tri again]

we DO understand the olympic trike toss event.
We've all been there.

If it runs for a minute or 2, I'd guess the fuel tank vent not working.
Can be funny too because it seems like it's running out of gas so we check 'em for the hundreth time and it lets air in for it to run again for a few minutes.
If that didn't make you laugh, I HAVE had success with the strangest of symptoms by cutting the last tiny bit off the spark plug wire so the spark plug cap has fresh copper to bite into.

On some rebuild kits, I've noticed float needles to be different lengths.

But on a lighter note re: float level, I'll run across the field and get halfway home and the trike dies because I forgot to turn the gas on.
Meaning it runs GREAT until it dies so I'm not too convinced that float level is all that critical considering the float bowl runs out of gas, if that makes sense.

I went for years thinking an .008" 'e' guitar string was the one for the pilot jet until I found a good one and .010" fits easily.
...always needed to run with choke, constantly sandblasting fouled plugs etc etc.

You should be able to see through them.
and your internal passages under the jets are clean?

could it be electrical?
lets see, is the timing set ok?
are the valves adjusted ok?

Spark advance plates have been known to get rust stuck and / or break the return springs.
Should be under the cover that says 'cdi'. and runs around the cam end.

I've got a couple right now that may get flying lessons here pretty soon so I may not be the one to give advice.

Good luck and Please keep us posted.

[keveldevel]

As far as the gas tank vent goes. it could be plugged its caked with rust inside the cap.
But that want my problem, Iv been running my test without the gas cap on. sooo.........

still stumped

[kb0nly]

I spent all last summer fighting a 85 125M, you can see it in my avatar pic next to my 200ES.

I had problems exactly like you, would only run with choke, was really finicky to get it set, etc. Check the plug, see if its running lean, i suspect it is since your using the choke and needle settings aren't helping. You most likely have an intake air leak.

I finally bought a new aftermarket carb off eBay and toss that on, was a huge improvement but still had a minor stumble and tuning problem, turned out to be the gasket between the intake tube and the head and the gasket between that carb spacer/heat insulator and the intake on the other end. They are just cardboard type gaskets. I bought some gasket material from Napa and used the intake tube to trace it out for the head end and what i scraped off of the old gasket to trace the inside opening, etc.. The other end is easier as you can use that spacer between the carb and intake tube to trace a gasket. Also make sure the o-ring on the front of the carb is good.

After i replaced the gaskets it literally fires on the first pull, choke is only needed if its really cold, on a warm day it pops right off and is ready to run.

[keveldevel]

Well made some new gaskets and still no change, only fires and run on choke. Runs for a minute and shuts down. cant dial in the idle it either screams or it dies. I did notice this time that it was back firing or burping while running this is a new development.

listening to offers lol