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blkdog
05-14-2013, 12:59 PM
Hello,

Just purchased a running 1978 ATC70 last night. Im trying to figure out the gearing. Are these a 3 speed. If so is it all 3 down? Im thinking it's only shifting into 2 gears. I was looking at an old truck when I saw this in the old boys garage. He said it ran but couldn't get it started at that time. He said he just put gas in it and it ran earlier that day because it had set over the winter. He said his grand kids had out grown it but ran fine for him and it was exactly what I was looking for for my boy. He called a few days later and had it running but he ended up taking of the ends of the breather to do so. I rode it a bit trying to figure out gear pattern and I let the boy do some laps. It seamed to run ok despite not knowing gear pattern. It did have a bit of a winning noise which I couldn't tell if it was the front wheel or tranny area. Last night I turned of the gas after using it. It started right of this morning but while getting it up to the house I noticed it would bog when put into gear and it would not stay running. So I started messing with the carb screw and now I can't get it started. I tried some gas in a syringe shooting into carb through breather but no luck there so far. Can anyone tell me the correct adjustments on both carb screws? I know it will run but wondering if my $150 steal was really a steal. The bike looks good for the age but it does need new rear fenders. couple dings in the gas tank but other than that good looking little bike. Any help and info would be greatly appreciated. Im not a mechanic but not afraid to research and learn and get my hands dirty :lol:

fastatc70
05-15-2013, 07:08 PM
The shift pattern is down with neutral at the top. The atc70 came three speed and four speed trans. I don't know what that trans is in that year but it at least a three speed. The adjustments are an air screw for idle mixture and a idle adjustment. 169566

The screw to the left, in the casting is the air screw start at 3/4 to 1 turn out from lightly seated. And the screw in the middle of the carb with the spring is the idle speed adjustment

fastatc70
05-15-2013, 07:13 PM
Run a inline fuel filter, clean the carb filter ( the part of the carb with the petcock ). Remove the petcock and clean the screen behind it. Replace the spark plug.

The investment was a good one if it runs and drives. They make china motors that will drop into the frame for a couple hundred dollars. The only hard part to setup is the carb.

Check out Hondaatc70.com they have a ton of parts for the atc70

blkdog
05-15-2013, 08:54 PM
Run a inline fuel filter, clean the carb filter ( the part of the carb with the petcock ). Remove the petcock and clean the screen behind it. Replace the spark plug.

The investment was a good one if it runs and drives. They make china motors that will drop into the frame for a couple hundred dollars. The only hard part to setup is the carb.

Check out Hondaatc70.com they have a ton of parts for the atc70

Thanks fastatc70, Im going to check out the site you mentioned. Im gonna get a carb rebuild kit for it and follow your instructions above. can you tell me what kind of lube gors in the crankcase / tranny. I was going to drain that as well and put in fresh lube. Thanks again

blkdog
06-05-2013, 06:35 PM
Well I got the bike running and was able to find the manual at the site listed in this thread which was awesome. Also I was able to get bike to shift correctly with some time. It seams to sometimes go from 1st to 3rd though sometimes. Does anyone know what could cause this? could it be the shift boot or is it a bad gear? Thanks for any info.

ps2fixer
06-06-2013, 01:20 AM
If my memory is working right, my 78 ATC90 was a 4 speed, N at top and all gears down. Don't remember for sure but it might have been the style where you could shift from N -> 4th and 4th -> N.

I have fenders in fairly good shape, but shipping them would be a pain. Also have a pretty nice gas tank, but the inside is rusty, no leaks though.

spookydoggg
06-06-2013, 03:40 AM
It will never work, sell it to me?:naughty:

briano
06-06-2013, 12:50 PM
It will never work, sell it to me?:naughty:


That would be great. Another thread started on your 70 shifting problems! Fix the ones you have first

fastatc70
06-08-2013, 09:39 PM
All atc70s shifted down except for the last year 1985 that trans shifted up like modern bikes.