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atc 70 rebuild help

7868 Views 9 Replies 6 Participants Last post by  MiniGiant

I recently purchased an 85 atc 70. I'm in the process of rebuilding this bike and i'm starting with a few things at first. At first I just want to make it run better and a little stronger.

I want to install a headlight. Can anyone please give me some tips and parts needed to do this correctly? I'd like an exact parts list not just a link to some parts needed. I'm not all that mechanical or electrical but with proper instructions and directions I can do anything. I'd like to just stay with the 6V option and have the light on when the bike is running.

Also, the bike seems to run ok. I haven't touched the engine since I purchased it. Usually starts on the first couple of pulls. However in first it bogs pretty well until it's really warmed up and if I give it too much throttle the power seems to really fall off even when warmed up and ran for a while. I'm wondering if changing my gearing down 1 tooth on the front will help this? What's stock gearing? 14/36?

I'm thinking of swaping out the stock exhaust for the Sterdy exhaust. Anyone have this exhaust? How do they like it? Will just adding exhaust and new air filter help add a little power? Do I need to rejet or change anything out with this exhaust? Any advice on new air filter, carb, etc. would also be helpful. I just need some all around help and advice and direction on which ways are the best here.

Thank you!!
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Take a look on the trails bike web site they do a few bits and peices for the atc
Take a look at they have light wiring harness ect. there
Can you please give me a link to that website?
Thanks. I've been on the dr atv website and have gotten an email from them. all they gave me was a link to the electrical page listing all those parts. I was wanting from them more specific details on what i need to install a headlight. I've never done this before so I have no idea.
Your bog is most likely related to valve adjustment. Try setting them to .002" to .004 dead cold, see what occurs.
Is it a stock carb? You can advance the timing on the motor, that will make it pull better. If you're going to change out the exhaust you might think about swapping out the carb too. You can go up to an 18mm I think a stocker is 13mm also run a open element filter. Swap out the points, a fresh set of points couldn't hurt.
Thank you, I'll check out the valve clearance
Yes, it's a stock carb. Thanks for the tips.
setting the points on it will definitely livin it up but as far as it having a stock carbs as many as i have seen no matter how many time we clean them at the shop we always end up replacing them. there are just some areas on the carb you cant get to. i would say clean the carb and then set the pionts. and see how it runs off of choke if it feels like its always choking run no air filter. that will be a dead give a way. time to replace the carb. i have an 84 atc 125 that will only run off choke with the air filter off. good luck good riding MG.
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