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mexicanyella · 06-18-2009, 01:49 PM

My two '71 bikes both came with 12/35 on them, and the one that is complete and running tops out in the upper 20s when it's running right and will rev out. That's with a 4.00x8 tire on the back, which is a little taller than the stock 3.50x8. Stock never-rebuilt '71 motor runs good but may be a bit tired; starts to run out of steam much above 7500 rpm wide open. Although that may be a result of the tiny carb and exhaust too. Gearing up to 14/35 is not a viable option; you gain a little speed but then can't climb any real hills without shifting down to second. I've not tried 13/35 yet, but will probably just leave it at 12/35 until I find some more power. I need "climb" more than "fast."

The '74 parts bike I have here came with 13/37, as ducatilover says.

06-18-2009, 01:49 PM	#3 (permalink)
mexicanyella El rey de los puntos Join Date: Aug 2008 Location: Troy, MO Posts: 976	Re: 1979 z50 My two '71 bikes both came with 12/35 on them, and the one that is complete and running tops out in the upper 20s when it's running right and will rev out. That's with a 4.00x8 tire on the back, which is a little taller than the stock 3.50x8. Stock never-rebuilt '71 motor runs good but may be a bit tired; starts to run out of steam much above 7500 rpm wide open. Although that may be a result of the tiny carb and exhaust too. Gearing up to 14/35 is not a viable option; you gain a little speed but then can't climb any real hills without shifting down to second. I've not tried 13/35 yet, but will probably just leave it at 12/35 until I find some more power. I need "climb" more than "fast." The '74 parts bike I have here came with 13/37, as ducatilover says.