Progress on my ATC 70 ***Check it out***

[jdparsons1]

Looks a bit better from when I first got it for $175. So far i've painted just about everything except some miscellaneous parts on the engine and the exhaust which i plan to paint with an aluminum high heat. I put a complete new gasket set on it and replaced all the oil seals and i put a new piston and rings in. Also put new tires and seat cover on.

It starts right up and idles great with the choke on but as soon as i start to take the choke off it spudders and dies. If i turn the pilot screw out an extra turn it will stay on but when i put it in gear i have to push the gas slowly or it will bog. Then i shift into second and it usually will bog a bunch and die. Does this sound like carburation or could it be points adjustment. I don't know what else to try with the carb. By the way, I completely rebuilt the carb so its definitely not a clogged jet or anything.


http://parsons.dynu.com/atc70/before1.jpg
http://parsons.dynu.com/atc70/before2.jpg
http://parsons.dynu.com/atc70/after1.jpg
http://parsons.dynu.com/atc70/after2.jpg

[JW125M]

youve got a lot a of time in that thing i bet! it looks good...did u check your gas??it might have bad gas.. :rolleyes:

[jdparsons1]

Nah,,, its definitely good gas. Just filled the tank with fresh from the gas station. When you hit the gas its sounds like its sucking air but i have spent an hour trying to adjust the carb and im fairly decent at adjusting these things. Any body have any other ideas?????

[KASEY]

this is a messy procedure but nessesary,,, pull both fuel lines off,make sure there is good fuel flow out of both lines,,, then pull the petcock off the carb check the fuel flow through the petcock,,, ,, there is a little plastic fuel screen behind the petcock ,,it has to be in there,, those jets are so small without it they will plug up with the smallest of stuff even out of a clean tank,,, then open the fuel drain on the carb and make sure you have good flow there too,, OH by the way great job on restore so far,,,, it looks very nice ,,, one more thing are you tryin to run it without the air cleaner? that might make a difference too,,,,

[kdagenais]

Another thing you might want to look at is all the parts in the pilot screw. There should be 1 o-ring, 1 spring, & 1 flat washer. If all of those items are not in there it will do exactly what you are describing.
Good Luck!

[jdparsons1]

I've actually done that already. Check to make sure the screen had nothing in it and I drained about 10 ounces of gas into a cup from the carb drain.

[jdparsons1]

Another thing you might want to look at is all the parts in the pilot screw. There should be 1 o-ring, 1 spring, & 1 flat washer. If all of those items are not in there it will do exactly what you are describing.
Good Luck!

I know for a fact that the screw has the oring on it and the spring is in there but i didn't see a washer, nor did one come in the rebuild kit. Are you sure there is one for this model?

[tri-freak]

nice 70, shes lookin great. i think you might have to just play with the mixture untill you get it right. put it in neutral, and go from idle to wide open as quickly as possible, and set it leaner and leaner until she doesnt bog. you will find the right mixture, just be patient. if this doesnt work, then it could be fuel delivery. this worked for my atc200e, and my tri-moto 200e. just play with it till you get it right. peace, tony.

[BigGreenMachine]

That is awsome looking, best 70 I've seen. :-D

Not to nit-pick but I would high temp paint the exhaust now that you've wire brushed it.

Good luck workin out the bugs.

[jdparsons1]

Yeah. I plan on painting it before i go riding. Just wanted to get the bike running smooth so im not dumping gas and getting grease all over the freshly painted exhaust.

[kdagenais]

It has been awhile since I worked on a 70 and the only book I have close is for the CT70 (Minibike). The diagram in the book doesn't even show the O-ring in it. Maybe someone here who has taken one of these apart more recently can provide more info for you.
I have run into this problem a couple of times when someone has taken the carb apart to clean it and doesn't realize the washer is still in there and it gets lost and then they wonder why they can't get it to run without the choke on. The bike will idle all day long (without being on choke) until you hit the gas. The washer is suppose to be in between the spring and o-ring so it makes a proper seal.
I hope someone here can verify it for so you can get it fixed.
Again Good Luck!

[KASEY]

OK I JUST TOOK 3 70 carbs apart and the air screws on all three have a spring and thats all,,, no oring no washer,,, the only oring is on the float bowl drain,,,, and two of these carbs are on great running 70's one a 79 the other a 84 and the third carb is off a 82,,,,, so i guess you need a book with a break down of parts,,,,,

[jdparsons1]

I just went out and screwed with it for another hour and still no luck. One thing i did notice is when i open the pilot screw enough to allow me to take the choke all the way off if i turn the idle up at all it starts to die also. same result as if i give it throttle. the only way i can get it to stay running is to keep the choke on.