1979 yamaha dt125 help

[geezerstiva]

well, i wasnt sure if maybe somebody on here might know anything about dirt bikes, but i figured i'd give it a shot!

its a 125cc aircooled 2 stroke engine. it seems to be flooding out. it will start and run at idle, whether the throttle is open or not and its a very bad idle. after about 2 min or so running like that, it dies and wont start back for a day or so. i think its flooding because after i have had it running, i pull the spark plug and its dripping gas. we tried adjusting the float level, and cleaning the carburetor really good. we know the needle valve is capable of sealing off the gas from coming into the float bowl. any ideas? heres a picture of the bike too, in case anybodys interested:

Thanks,
Andy

[jasonpaulbauer]

Sounds like the needle valve is sticking or the floats not adjusted right.... Also could be that the float isnt floating..... take the float off and put it in a cup of fuel and verify that it doesnt sink.

[Ghost]

how did you clean your carb? is your needle adjusted wrong? im not really familiar with old carbs, but the carbs im familiar with, you can raise and lower the height of the needle.


are you sure your choke isnt on or stuck on?

if the float isnt adjusted right the extra gas should just run out of the overflow on the carb.

[eurotiva]

Also on a bike with that age to it. Look at the condition of the slide itself. I've had a few bikes (dirt especially because of 2 stroke vibration) Where the slide wore enough to let air by. That air picked up extra fuel. I've been a bike mechanic for the last 10 years

[Levitan]

Sounds like the needle valve is sticking or the floats not adjusted right.... Also could be that the float isnt floating..... take the float off and put it in a cup of fuel and verify that it doesnt sink.

I second this!

[blkfordsedan]

It's not flooding, it just needs more air...........what it really needs is a turbo! LOL
Eurotiva can probably fix you up.

[geezerstiva]

what is the slide? we did check that the needle valve would seal by taking off the bowl and pouring gas in the inlet. when you pushed the float up it sealed the hole, so i dont think thats leaking. also, i think it should be set right, cuz the guy i bought it from said that it just started doing this all of a sudden. it was running fine, then started doing this. i will check the float to see if its floating though. and i cleaned the carb with air pressure and carb cleaner. and the choke is definitely in the off position. i guess it could be letting fuel leak by though. thanks for the input guys!

[jasonpaulbauer]

Never assume a float is set right. Check it!

[geezerstiva]

how do you check it though? it doesnt have a sight glass or anything.

[jasonpaulbauer]

Look at the manual. It should have setting specs in the manual. You'll likely have to completely remove the carb to do so.

[geezerstiva]

well... i dont have a manual. and i've had the carb off about 10 times, so thats not a problem :lol:

[jasonpaulbauer]

Just had another thought.... I think the DT125 has an autolube carb. Are you running premixed fuel or letting the carb mix the oil for you, or BOTH? Both would be over kill for the engine and would also cause similar symptoms.

I suggest picking up a manual for the bike....

I'll look when I get home to see if I have one that I could possibly look up the carb settings in, but not sure if I do or not.

[jasonpaulbauer]

Check this link for the "how" on setting the float level.

http://justkdx.dirtrider.net/floatlevel.html

the height will be different, but I'll see if I can dig up the setting.

[jasonpaulbauer]

I cant seem to find a float height setting listed anywhere online specific to the DT125. I did find that the setting for a DT175 is 21mm....

Use method 2 listed in the link I posted above... unless you can find the setting somewhere.

[geezerstiva]

hey man thanks a lot! i'll try that when i'm workin on it next. i really appreciate it!

and yes, it is an autolube carb. first one i ever saw :lol: