Hey guys i'm in desperate need with my ATC 70 owned since new by my dad in 1982! been garaged and stored so in mint condition.

So the story got it out of the garage new plug and fuel filter started but would only run on choke. So ran for a while and spark plug buggered up.

Decided to buy a new carb off ebay to try fix the problem have fitted that and have the same problem as the old carb?

I have checked the point and have good spark! put an air filter on but still will only run on full choke and then the next day wont start because the spark plug is all black and sooty and wont clean up using a wire brush so is full of oil bunging the plug up!!

I'm in desperate help can anyone suggest anything? I've done a bit of research and wondering about positions of the needle in the carb? Surely a new carb doesn't need the needle adjusting?

Cheers

Nick

 

forgot to add that i have compression tested and all good 7.5! cheers

 

"So the story got it out of the garage new plug and fuel filter started but would only run on choke. So ran for a while and spark plug buggered up."

Sounds like you either have a vacuum leek or need to adjust the carb. Get it 'running' then spray starting fluid where the carb meets the intake, where the intake meets the head, in the head gasket area, and along any vacuum lines that may be present. DO NOT SPRAY THE CARB INTAKE. Listen for the engine to change speeds if it does you found a vacuum leak. If not try adjusting the carb. First be double sure the carb is clean (u said have a new one).
1) Run the air screw all the way in til it stops (do not tighten it or you will bend the needle and have to replace it)
2) now back it out 2 full turns (720 degrees) Fire the bike and adjust the idle screw until it idles easily with the choke off.
3)Now turn the air screw in/out 1/2 a turn whichever makes the bike run fastest.
4) Set the idle screw so it just idles easily again

 

"So the story got it out of the garage new plug and fuel filter started but would only run on choke. So ran for a while and spark plug buggered up."

Sounds like you either have a vacuum leek or need to adjust the carb. Get it 'running' then spray starting fluid where the carb meets the intake, where the intake meets the head, in the head gasket area, and along any vacuum lines that may be present. DO NOT SPRAY THE CARB INTAKE. Listen for the engine to change speeds if it does you found a vacuum leak. If not try adjusting the carb. First be double sure the carb is clean (u said have a new one).
1) Run the air screw all the way in til it stops (do not tighten it or you will bend the needle and have to replace it)
2) now back it out 2 full turns (720 degrees) Fire the bike and adjust the idle screw until it idles easily with the choke off.
3)Now turn the air screw in/out 1/2 a turn whichever makes the bike run fastest.
4) Set the idle screw so it just idles easily again

 

5) Slowly turn the air screw in/out until the engine idles as fast as possible and doesn't bog when you snap the throttle open.
6) Return idle screw to where it idles easily again.
7) Repeat steps 5&6 until you get the best results.

Oh and to clean a plug I like to use a propane torch. Just flash heat over the plug end not the ceramic. If you see it get even slightly red pull the torch away for a few seconds to allow it to cool. It will usually burn off the carbon and if your careful not to overheat the plug it wont hurt anything.

My 185 used to foul the plug in just a couple hrs and the carb adjust all but stopped it (still fouls every couple weeks cause it burns oil) and I have always cleaned it with a torch. I'm still using the plug that was in it when I bought it almost 2 years ago.