My atc 70 runs like crap

[ganan]

HELP!!!My trike starts on the first pull and stays running. When it's warm it keeps popping and if it's not popping it just has no power. (but it mostly pops,with a quick thrash on the throttle) air/fuel mixture is at two full turns out and I've tried adjusting either way. Carb is clean and gets plenty of gas. Air filter is clean and oiled, and plug is new.HELP!!HELP!! I just bought this for my son. but I'm having way more fun, I think I'm going to have to get another.

[The Goat]

air fuel is 1 and 1/4 turns out if memory serves correctly. maybe someone can chime in. you using the stock air box and filter or a pod?

what's the position of your needle?

[ganan]

I'm running the stock filter. I've surely hit 1 1/4 turns in my adjustments, and as far as needle position, your going to have to talk to me like I'm 2. Thanks

[oneroom42]

i am having problems with my 70 also. i have a turn down air filter and i put a 62 jet in and it ran like crap. i could not open full throttle with out it acting up. i pulled the plug and it was black. too rich so i put the stock jet back in and cleaned every bit of the carb. still i can not get full throttle out of her. with the choke on i can punch it and it revs right up. i pulled the plug and it is still black. so i then adjusted the needle on the clip to lean it out but it still is not right. i messed with the set screws and cant get it any better. what is my next step for sale?

[nathanronan]

In the manual i have for it, it says to turn it in until it is all the way seated, then turn it back out 1 and 1/2 turns. Then it says start the engine and turn it back in until it stalls and then turn it back out 1 full turn.

hope this helped

[oneroom42]

thanks for the help but that wont work. it isnt possible because it will run with the fuel that is already in the carb. it doesnt have an air fuel mix screw. just a screw that allows the fuel in the carb.

[ganan]

I thought that was the mix screw?

[nathanronan]

do you have a manual for it?

[oneroom42]

i read somewhere earlier that it isnt. i could be wrong due to false information. either way adjusting that screw did not make any diff. on my little trike.

[nathanronan]

there is a pilot screw and then there is a idle screw. Like i said before in my other post that is where the pilot screw should be adjusted to. It looks like the pilot is on the left and the idle screw is on the right. The pilot screw is lower than the idle screw if that helps locate it.

[oneroom42]

yes i do have the manual and that doesnt seem to help me a whole lot when it comes to fine tunning.

[ganan]

I don't think the pilot screw is a big part of my problem, but it may be for oneroom42 if its not making a difference where he puts it

[nathanronan]

is the float valve set right?

[ganan]

doesn't it just sit in underneath the float? My expertise does not involve needles and jets. I cleaned it and put it back together, and it runs the exact same (very poppy)

[ganan]

I mean above the float, sorry.

[oneroom42]

ganan, the poppy noise, is that backfiring inside your carb? mine does that sometimes as well.

[Brad200X]

Do you have any exhaust leaks? That can cause popping. Also, you could have gotten a bad plug. Just because it's new doesn't mean its good. Trust me this has happened to me before.

[nathanronan]

if the pilot screw is set right im not sure what it could be. Thats all i could think of :wondering :wondering

[oneroom42]

im going to go try that screw again. i have tried 2 diff. plugs and it does the samething with each. i'll be back and let you know.

[Preddy05]

Did you try setting the points? if they are not set right its not going to run right.

[Daddio]

Almost sounds like a timing issue. How do the points look? Are the valves adjusted properly? It could even be a worn cam chain.

[oneroom42]

well i messed with the mix screw again and the only way it would stall is when the screw was out in my hand. i put a new condensor, points and one of those little oiler sponge things and set the timing. once again it runs good with the choke on. what sense does that make?

[3Razors]

Do you have the stock air box/filter on? 70's run soooo much better with the stock unit over a clamp on filter.

[oneroom42]

no i have the turn down clamp on filter. i was even thinking about throughing the stock assembly back on just to see what happens cause im running out of ideas. im actually thinking of getting a cdi unit off of ebay and do away with the points crap! i heard it added some power.

[3Razors]

The best thing I can tell you is to put the Stock air filter assembly back on. The 70 is extremely finicky and runs night and day better with the stock unit. Try it, Im pretty sure you will be suprised. Also set all your jetting specs back to stock when you do this.

[blue27]

also check that the jets are clean, you need to go through them both and make sure all the holes are open, On the smaller jet use a wire from a wire wheel or brush if you do not have a jet cleaner.

[CRAZY70MAN]

float level is 20mm which is measured with carb inverted from upper edge of float and the mixing chamber flange. Pilot screw run in until it seats and back out 7/8 to 1 1/2 turns out. Idle adjust 1500 rpm, or by ear when warm. Main jet was a #58 after 1974 and #60 before that. Try and clean ALL passages with torch tip cleaner. Triple check main jet. has to be clean clean clean. Clean main hole and tiny side holes with wire from a wire brush. Just had one doing same thing, told myself carb was clean, cause I just cleaned it personally. Ran myself ragged with timing checks, plugs, coil wire and plug cap. Took carb off other night and sure enough, main jet had tiny,tiny piece of dirt in it!! Runs great again. Hope this helps good luck

[CRAZY70MAN]

Clean main jet again. Has to be spotless. 20 mm is float height from mixing chamber to uppermost edge of float with carb inverted. #58 jet 78-85 and #60 pre 78. 7/8 to 1/12 turns out on pilot screw. Clean all passages again and again with tip cleaner. Clean main jet side holes with wire brush wire. The needle is located in the carb slide. Push slide against spring and cable will slide out of it. Take out s-clip that holds needle. There is a c clip that sets height. Stock was middle notch on needle. Moving clip down more fuel, clip up less or lean. Hope this helps.

[The Goat]

Therenis a cheaper csi than the one on eBay. Mine was 120... Schmees was 40 or so. He has a thread around here somewhere.

[Blown 331]

I would also recommend the stock air filter assm and set the points. On the 70s the ignition timing is set with point gap. As the points wear the timing gets later. This was a problem on both of mine plus one more that I had worked on and they had similar probs to yours.

[bigboy_toy85]

when it pops does black smoke come come from the exhaust? I'd say check the spark plug. Or scheck the float in the carb. It could be getting too much gas.

[oneroom42]

i put a brand spankin new idler jet in and put stock air system back on. main jet is stock and cleaned with a piece of wire and carb spray. still only runs good with choke on but stahls without my finger on the trottle. idles good with choke off. but wants to shut off when i give it gas. i ordered a rebuild kit for the carb so i hope it helps. i dont know why it would cause everything has been cleaned about 5 times now. how do you adjust a stock float? and what would cause a float to go ba anyways?

[Blown 331]

i put a brand spankin new idler jet in and put stock air system back on. main jet is stock and cleaned with a piece of wire and carb spray. still only runs good with choke on but stahls without my finger on the trottle. idles good with choke off. but wants to shut off when i give it gas. i ordered a rebuild kit for the carb so i hope it helps. i dont know why it would cause everything has been cleaned about 5 times now. how do you adjust a stock float? and what would cause a float to go ba anyways?

Did you adjust the points? Thats EXACTLY how my first ATC70 was acting. As the points wear the gap gets narrower which retards the ignition timing. Point gap is the only way to adjust ignition timing on a 70. You wouldn't normally think the choke would affect an ignition timing issue but it did on mine and now it runs amazing. It was so bad before I could not ride it at all, it would only idle, if I touched the gas it died but choking it would keep it running. I swapped the carb to it from a good runnig ATC70 and it acted the same way.
I know that is your problem so either adjust them and ride or keep going in circles.

[oneroom42]

okey dokey blown 331. thanks, i thought i had them set right when i replaced them cause it runs good with the choke but from you having the same situation i cant complain. i will give it a shot and i'll let you know how i make out!! fingers crossed!!! i want to ride!!

[oneroom42]

ITS ALIVE!!! HA HA HA !!! ITS ALIVE!!! the points were set wrong. something so simple was overlooked. 2am and im up and down the streets smackin gears!!! let the atc70 addiction kick in!!! thanks a million blown 331 and everybody else for all your help1!!!

[Blown 331]

ITS ALIVE!!! HA HA HA !!! ITS ALIVE!!! the points were set wrong. something so simple was overlooked. 2am and im up and down the streets smackin gears!!! let the atc70 addiction kick in!!! thanks a million blown 331 and everybody else for all your help1!!!

Awesome! It seems like every 70 I get my hands on benefits from opening up the point gap. The points get neglected quite often I guess.