ATC70, needs top end rebuild - questions!

[Baba Yaga]

Bought a 1985 ATC70. Burns oil, compression is approx. 105 with the throttle open.
Specification is up to 170 PSI.

Would like to keep it all Honda, but can anyone comment on the Chinese top end kits - cylinder/piston/head ? And of the Chinese variety, is there a kit that is better than others? Tempting, if they're decent, reliable, and an all in one kit has it's appeal.

Haven't taken it apart yet, was thinking possibly just a hone/ring/gasket job if everything else was decent.

Thanks!

[jb2wheels]

I put an 88cc cylinder and piston kit from DRATV (http://dratv.com/88ctalalc7.html) on a TRX70 a few years back. An excellent $100 spent.

I lapped the valves at the same time. I believe the 88 kit came with all the gaskets including new valve seals if needed.

Thing ran awesome - amazing how much difference a few cc made.

[Baba Yaga]

Thanks. So, using that kit, you retain the original cylinder head? Any other mods required (carb, head, etc.)?

Was lapping the valves as simple as seating them with the lapping compound?

[coolpool]

I bought a complete chinese-ium cylinder, piston, rings, wrist pin and gaskets for under a 100 to my door; and in Canada to boot! The original head was retained with lapped valves. Direct bolt on and is still working good all these years

[Baba Yaga]

Coolpool, did you go 88cc, or stock bore?

Haven't pulled it apart yet, but will soon!

[jb2wheels]

Yes, I used original head.

Yes, I lapped with lapping compound on the valve and seat, a drop of oil on the guide, and seat the valves with a bunch of back and forth rotation until the valve and seat are pretty and seal verified.

I bumped my main jet one size. Not sure if it was needed or not. It ran great and I never looked at the plug again.


Thanks. So, using that kit, you retain the original cylinder head? Any other mods required (carb, head, etc.)?

Was lapping the valves as simple as seating them with the lapping compound?

[Baba Yaga]

Sounds like an easy swap to add a little more power. Does anybody else besides DrATV sell the 88cc kits?

[90nut]

Tbolt usa sells the 88 Kits, multiple options. I have the full "race" variant. Different head, intake, carb. Carb sucks, will be replacing it with a mikuni at some point. I have one of the klx kits on another bike, and it ran and still runs great right out of the Chinese box. Didn't even have to jet the carb.

[Baba Yaga]

I think I'll order one up, but just the piston & cylinder kit.

Thanks all!

[coolpool]

Sorry baba, a little late to the question; stock configuration only.