Atc 70 won't start

[Atc kyle]

Hi there, I recently purchased a 1979 honda atc 70 with a 1982 motor in it. I knew when I bought it that it ran poorly but I figured I could handle it. It would idle, but not that great. When I applied the throttle the rpms would come up a little but just felt like a complete dog only driving very slowly. The guy I bought it from said he changed the points and condenser so I thought maybe the timing was slightly off so I adjusted it myself and after checked the spark and there was a consistent blue spark. I also disassembled the carb and soaked every port and valve in carb cleaner then blew clean with air gun and reassembled it. Now since doing all that I can't for the life of me get that thing to start, also I don't know where to begin with the carb settings. I need help and I'm not exactly sure where to go from here, any info or suggestions would be much appreciated, thanks.

[Tomcall]

I have 2 atc70's and will make a few suggestions. These are simple and you may have checked this before but.......
Is the carb getting fuel ok? If it is getting fuel is the fuel clean? Is the fuel tank in good shape with no rust?
I am assuming you replaced all the jets in there correct position? Did you clean them out by running a thin wire thru any opening to be sure?
The pilot screw on the outside of the carb has a general setting of one and a half turns out after screwing all the way in. Be gentle screwing it in. If that is all good sometimes the float will get stuck closed. When has happened to me I will tap the bowl of the carb with the handle of a screw driver a few times and that normally does it. Another idea is to check that the fuel lines aren't clogged. I have had all of this happen some time or another. Hope it helps. Post how it goes.

[barnett468]

you can try the following as well.


get a 10" piece of clear plastic tube and connect it to the carb bowl drain.

hold the open end next to the carb and even or slightly above the top of the carb.

open the petcock and float bowl drain screw.

the gas will enter the tube and the level should be from even to the carb body bottom [not the bottom of float bowl] to around 3/16" below the carb bottom.

if it is much out of range correct it.

if it is high either a float might have a hole in it or the rubber tip of the needle/fuel shut off is damaged and allowing gas past when it is closed. the carb cleaner might have "eaten" it, lol.

look at the plug very closely after trying to start it. if it looks dry and the float level is correct your idle/start circuit is likely plugged.

if it is wet it is likely flooding out.

if the gas is not brand new change it.

[CRAZY70MAN]

How did you set the timing?? New points were how old?? Timing issues are common with these. They are very picky on timing settings and fuel issues. I would start at the tank and clean petcock screen and make sure tank has flow to crb. Install a inline fuel filter and new plug gapped at specs. Make sure plug wire cap has good connection. The caps twist off and on. You can remove and cut a fresh end on the wire and screw cap back on tight. Check the points to see if are any black spots where arcing may hav occured? Just replace if they are fouled, they are cheap. The carb jets have to be cleaned with a small wire in all passages. I use a wire from a wire brush. Especially pilot or idle jet. Here is a manual to help ya along... follow it to set carb and points...

http://www.3wheelerworld.com/showthread.php/141106-atc-manuals?highlight=atc+70+manual

[Tomcall]

If you are getting a spark then it points to a fuel problem.

[Atc kyle]

Thanks for the tips guys. I checked the fuel lines between the tank and the carb as well as the filter screen behind the petcock, they were clean and clear. I haven't checked fuel level in carb with hose yet or used a wire to clean out carb ports or jets which I will do yet, but I have checked the spark plug a couple times while tinkering on it and it does get wet. As far as setting the points goes, I turned the flywheel until the T lined up with the mark on the casing. I installed new points as I could see the points installed were not seating flat against each other. Set the gap at .014 and I had a good spark after that. I was in the garage today and just figured I would check the valves and set them if they needed it. Actually found that the valve adjuster screws had backed right off and one nut had actually fallen right off the screw, luckily found it. With the engine at tdc I set the valves both intake and exhaust at .002. Still can't get it to fire, guess, I'm left with a fuel problem.I'll have to give that carb a real go over as I'm not sure what else to do. Thanks a ton for the helpful info guys, I will see what I find from here and will post with any new success or problems lol.

[Tomcall]

You may want to consider a new pilot screw valve, and new jets. When I get into a carb with a new, old trike, I replace everything I can still purchase.
To check if the float is stuck, just connect the tube to the bowl drain and open up the small screw at the bottom of the bowl. Make sure you have the petcock turned to "on" or "reserve" depending how much gas is in the tank. If the float is stuck closed no fuel or very little will come out. If it's stuck, then no fuel and no start. If it is stuck, I would replace the small valve with the little rubber tip that attaches to the float and the floats if they look suspect. And lastly, sometimes just buying a new aftermarket carb solves the problem.

[barnett468]

Still can't get it to fire...

I have checked the spark plug a couple times while tinkering on it and it does get wet. As far as setting the points goes, I turned the flywheel until the T lined up with the mark on the casing. I installed new points as I could see the points installed were not seating flat against each other. Set the gap at .014 and I had a good spark after that.

I have checked the spark plug a couple times while tinkering on it and it does get wet. ...guess, I'm left with a fuel problem.Hi Atc kyle;

I hate to tell you this but it may never run like that.

You set your points to the wrong mark. they should be set to open on the "F" mark.

You can use a continuity tester to check when your points actually open and compare it to that mark.


Point setting page 3.

http://www.oscarmayer.net/atc/manuals/honda/ATC70_73-84.pdf




Once they are set, I would insure the plug is clean and has good spark then try to start it with no choke and 0 - 1/8 throttle. If it does not start, look at the plug. If it is wet, your float level might be too high or the needle and seat might be leaking or a float is sunk or stuck etc.

If the plug is dry, try it with full choke and 0 - 1/8 throttle.

A little shot of flammable brake cleaner or starting fluid often encourages starting. Some might advise against doing this.

[webbch]

Agree - T mark is top dead center. It is the correct point at which to set the VALVES, but the incorrect point at which to set the TIMING. Points need to open slightly before TDC, which is the F mark.

Personally, with a new-to-me trike in non-running or poorly running condition, cleaning the carb would be pretty high on the priority list as well. During re-assembly, make sure to set the float level properly. See How to properly check float level (http://www.3wheelerworld.com/showthread.php/164291-How-to-properly-check-float-level) thread for how NOT to set the float level, lol.

[Atc kyle]

I set the points so they begin to open precisely as the F mark lines up with the mark on the case with the flywheel turning counterclockwise. As the T lines up with that mark on the case I've got a gap of .014. I've read that if you install new points that the gap measured when the T reaches the timing mark on the case that the gap should measure between .012 to .016. I do have great spark from what I've seen. I think I'm going to look into a carb kit for sure though or even a complete new if I find one for the right price. I do have another question though. When I got the trike, my kill switch was not hooked up all the way. The green wire was mounted where the coil bolts up to the frame and the black wire was just dangling there. Does it need to be hooked up, or can I run without it? Oh, and one more thing. I have plastic float in my carb and the needle just sits in a middle groove on that float. Am I missing a clip that hooks onto the needle and then slides onto that float tab or is it supposed to sit in there loose like that?

[barnett468]

ok, i misunderstood your previous point setting explanation. it is close now however i would make sure by using a continuity tester as i suggested earlier. this will guarantee when they are set correctly.

since you have spark, your kill switch is not preventing it from starting. i would at least tape up the end of the loose wire.

[Atc kyle]

Cool, ok I will check it with my multimeter too. Thanks again

[barnett468]

When I got the trike, my kill switch was not hooked up all the way. The green wire was mounted where the coil bolts up to the frame and the black wire was just dangling there. Does it need to be hooked up, or can I run without it?
If you want the switch to work test it with a continuity tester first. if it works, connect the dark green wire to the frame [possibly the coil mounting bolt] and the black wire to the positive side of the ignition coil.

[barnett468]

Cool, ok I will check it with my multimeter too. Thanks againYour multi meter may have a continuity setting. If it does it is likely identified by the following symbols >l