ATC 70 top end rebuild

[f76]

Unfortunately the top end on my 70 needs to be rebuilt. I am familiar with the engine swaps and such but I would prefer to keep it close to stock 70cc performance for my nephew. I see a few complete top end bolt on kits ranging from 88cc to 150cc, are there any recommended kits vs others?
The amount of money I would pay for a top end kit is within a $100-$200 of a smaller complete motor. Are these motors reliable and fairly straight forward bolt on and go? I'm exploring the the options but would like to hear from those who have done the swaps or rebuilt their top ends.
Thanks!
http://uploads.tapatalk-cdn.com/20160906/2f5e2541c479a29d3a935901ba580a6d.jpg
That's how I bought it, price was right.

[oscarmayer]

For reliability, stay stock and just get the next sized piston and bore the cylinder to it.
If you don't mind doing tinkering and dropping a different carb and exhaust the 88cc is the best bet. If you get that get a mikuni 24mm carb off eBay for it. $56 shipped usually. And then some jets.
You will want to get a 110-125cc exhaust system as it is larger and will allow for more flow. This all bolted on should get you from 3.5 hp to 7hp


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[Mackus84]

Why not just get it bored next size up? Probably cost ya about 100-125 for the bore,hone, and piston and rings. Have it back together in a few hours

[steveo3318]

I have 5 70's. I just done a 125 Lifan swap on one and absolutely love it. It's a beast and seems dependable only time will tell, but I will do more lifans . I am doing an 88 jug and piston from spanglers on a trx70 currently with stock carb and exhaust. Being told I can get away with just jetting the carb from spanglers guys. I should have an update on it this weekend. I also am awaiting an electronic ignition for one of my stock atc70s. After running the Lifan with cdi and trx with cdi I want all the points gone on any atc I own. I will say this. Don't buy a cheap jug kit off eBay. I tried one and the oil rings were never right and destroyed the jug upon start up. They were way to tight. I knew better than trying but I have had less fun pissing away 50 bucks.

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