Advanceable flywheel on ATC70?

[Blown 331]

Has anyone or is it possible to put a flywheel from a Hand clutch model Honda 70 on a ATC70? I wonder if it would be worth it? I have two 4-speed hand clutch Trail 70s and an SL70 that is also 4-speed and hand clutch. These models have a flywheel with weights on the inside that fly out and advance the timing kinda like in an old distributor for a car. Obviously that will make more power but I wonder how much? I was looking at one of the flywheels and there is no place for the recoil starter cage to bolt on. That could probably be overcome. But someone told me that one year Honda chanaged the taper on the crankshaft where the flywheel bolts on, so older flywheels and newer flywheels will not interchange. Anyone else heard that? Thoughts?

[KASEY]

wow its about time someone else asked this question... i wondered this 10 years ago,,, i never tried it,, because the 70 only makes 3.3 hp ,,, so i never figured it was worth it,,,, but now i think maybe you should do it and report back ,, maybe it would be just enough to actually make a difference in the topend.. i was always looking bigger,,,

[atc500x]

My sl70 have the flywheel with weight,and it's not the same crankshaft as a ct70 with auto clutch.if this can help....

[Daddio]

It would surely require machining to the flywheel so that the pull start could be used. I have an sl70 engine that I bought for the manual clutch set up to use on a ct70 but it was missing the flywheel. I'm not sure how much of an increase this would make in hp on something with 3.3 hp. How about the cdi conversion for the 70? That seems like it would be easier. I'm building a 70 now and I've been kicking all of these ideas around also.

[Vealmonkey]

Instead of trying to machine everything to fit the atc70 engine, why don't you just swap engines? It would seem much simpler. I have an suspension 70 with the xl70 sitting in it right now. It's a bolt on switch.

[Daddio]

Instead of trying to machine everything to fit the atc70 engine, why don't you just swap engines? It would seem much simpler. I have an suspension 70 with the xl70 sitting in it right now. It's a bolt on switch.

Isn't that a kick start engine?

[Vealmonkey]

Yep, kick start engine.

[greenhuman]

You can do it but only certain models. The taper didn't change, just the crankshaft length.
The 70 models with the fat pull starts( steel flywheels) the SL/XL advancer flywheels fit right up. If you want to put one on the earlier models, you will have to fit the SL/XL 70 crankshaft and make a spacer for the thinner pull starts.
Theres a little bit of work fitting the pull start ring but its doable.
This mod certainly makes a big difference to revs and top end power.

[BigRed_Ryno]

So apart from originally being from different bikes, whats the difference in these two? (apart from the price)

http://cgi.ebay.com/ebaymotors/ws/eB...3AIT&viewitem=

http://cgi.ebay.co.uk/ws/eBayISAPI.d...MEWA:IT&ih=018

They've both got advancers in them, do they both acheive the same thing?

'coz apparently most C70's came equiped with the second one?? my atc70 doesn't have it.