Last modified: 2026-01-18 16:46:29
ZS190, supposedly 16hp.
I have some 17x1.6" wheels that look to be front wheels from a motorbike, they have one side open where a drum brake assembly could fit and the other side blank.
Bot says the biggest tyre you can put on a 17x1.6" wheel is 3.00-17, and for example a Kenda K272 looks good and is about £45 per tyre.
I've ordered front leaf springs for a "Club Car" golf cart. They have 2 leaves but I will remove one.
Light press-fit some bushes inside the bearing spaces in the wheel, with a close fit over the axle, so that the wheel is accurately located. Drill through the wheel, spot-face with a counterbore tool, bolt to a flange at the back.
Bolt-on taper-lock hubs are available:
Alternatively weld-ton taper-lock hubs are also available.
We can use bearings inside the wheel - but probably want to increase the spindle diameter from existing 15mm. Bot suggests you really want like 25mm. It's possible that I could make a separate "spigot half" for the inner and outer bearing, and have bearings larger than 42mm outer diameter but they sit outside the wheel hub, but I think not necessary.
But a "6905" deep-groove ball bearing is 42mm outer diameter, 25mm inner diameter, 9mm thickness, cheap and readily available. Alternatively a "71905" angular contact bearing fits in the same dimensions (also 9mm thick) and takes higher load, but costs over £100 each.
And then we need something, probably bolted through the wheel, to carry the brake disc, with clearance for the caliper.
Check this out: https://www.ebay.co.uk/itm/204669651717
Looks to have:
I've ordered one.
And needs I think at least 25mm clerance from the inside edge of the disc to the nearest surface of the wheel, for caliper clearance.
To mount the rear disc I will want an adapter for a taper-lock hub. Either weld-on or bolt-on, with an appropriate adapter plate in either case. Or perhaps get a bolt-on one but machine it so that the disc can mount directly to it?
A BF12 taper lock hub has 6 holes on a 100mm PCD and has registers at 74mm and 80mm diameter. And the 1210 bush has max. diameter of 47.55mm. So probably it is possible to machine this to take the disc directly.
I've ordered a "universal go-kart reversing gearbox". It is sold as being suitable for up to 13hp, but a unit that looks equivalent is sold elsewhere for up to only 7hp, so unclear how well this will hold up. I guess we'll find out.
Teardown begins at 10:30 in https://www.youtube.com/watch?v=Sr9sfgW3vsg
I think the ratio is 1.25:1 in forwards mode.
Another option is a "GY6" reversing gearbox.
GY6 reversing mechanism disassembly is here: https://www.youtube.com/watch?v=ALu3WWRsG18 - happily, nothing inside is spinning while it's in forwards gear, I think this will be adequate provided it can be mated to either the ZS190 gearbox output or the axle.
This guy puts it on a 50hp engine: https://www.youtube.com/watch?v=o4c4AuKVVJw - he has a follow-up https://www.youtube.com/watch?v=pJmb9dp08mQ where something did fail, but it was nothing to do with the reversing gearbox, that's encouraging. And a teardown in https://www.youtube.com/watch?v=K0RRHEuYprw in which nothing appears damaged.
Note the GY6 reversing gearbox has a reduced ratio in reverse, so it matters which way you drive it!
The GY6 gearbox may be able to handle more power. One guy was having the "universal go-kart" one keep skipping teeth, although I don't quite understand why, it's possible his issue was with some other part of his drivetrain.