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HISTORY : Here's an excellent article on the history of Indian . http://www.icenicam.org.uk/articles5/art0084.html
Petcock option for Indian Mopeds
The Honda Gas Fuel Tank Petcock for CBT125 M16*1.5 will fit, but the valve knob points upward instead of to the right. You will need to modify the side plastic to access the fuel valve.
Or, acquire this fitting. This is a female M16x1.5 with a barbed end for 1/4" fuel line. You'll also need a 9/16" (technically, 14mm, but 9/16" will do) o-ring for inside that fitting to the tank barb. Regular rubber ones are available in the plumbing department of a decent home improvement or hardware store, or order a Viton o-ring for fuel resistance. Next, connect a 90 degree fuel filter. Finally, between the filter and the carb, use a 1/4" inline fuel valve, available at any lawn and garden section. This may also require modifying the plastic side cover to get that cover to fit.
A few tips on the engine as I recently completely rebuilt mine. First the carb, if you're having trouble with your carb, need a replacement, or your moped didn't even come with one at all (like mine) I've found that this one https://www.ebay.com/itm/Carburetor-For-Honda-Z50-Z-50-R-A-RD-50cc-Dirt-Pit-Bike-50R-MONKEY-BIKE-XR-CARB-/372889232913?_trksid=p2349624.m46890.l49292 (or just search for 'Honda Z50 monkey carburator') that works perfectly as a replacement and is fairly cheap (this is for the models that originally come with the Mikuni carb) . Another tip is when adjusting your valves they give you a fairly large range I've found the moped functions better and sounds better on the wider side. Lastly, at least for now that I can remember, is the pawls that are used to engage the engine when pedaling don't always work and they break or wear away easily so if your engine is switched to on and your pedaling it and nothing happens its not broken just keep pedaling and eventually some of the pawls will engage.
Indians are 4 strokes, which means less power and less go fast potential, and they're also considerably more difficult to work on. Indians use a one-of-a-kind engine, meaning NO cross compatibility with other engines, and parts are hard to find. They are poorly built Taiwanese clone of the Honda PC50; they can use parts from those, however it is equally if not more difficult to find parts for the PC50.
The easiest option is fabricating mounts for a Puch E50 engine or a Tomos A35. Either of these engines should cost around $100. A 70cc kit for an E50 is about the cheapest (and one of the easiest) kits available for any moped engine, and it would run around another $100 depending on the kit brand and quality up to 300 if you wanted to do a complete upgrade with new pipe, carburettor, crank and head, it could cost up to $300. The A35 is a faster engine in the end because it's a 2 speed, but it's also more work and it requires more maintenance (like replacing clutch pads). Swapping the engine should get you going easily 40+ for around $200, and for a full E50 build, 55 is entirely achievable for around $500 total (including engine + mounts). To keep it four stroke, there are Lifan and Linhai Honda clone engines around $300 new and complete that you could have also fabricate a mount for.
For upgrading the Indian engine you have a few options, most of which involve finding a good machine shop.
- First off, tune it. Get the valve timing perfect to the wider end of spec from the manual, and the ignition too. This should get you running 25-30mph.
- Advancing the ignition can help the top end by revving higher and you might be able to get closer to 30 and a little over.
- You can also swap out gearing to get more top end, but you'll be slow off the line and probably unable to pull heavier people.
- Tires overfilled can actually give you 1-2mph on the top end as well.
Taking off the exhaust or drilling holes for more flow and removing the air filter (you can use pantyhose to keep crud out) will allow more fuel flow through. You'll loose some efficiency but gain power. You'll need to buy a bigger jet to match or the performance will probably drop. If you're feeling confident, you can try drilling up your existing jet, but that's easy to mess up, and near impossible to undo.
Buying a thin sheet of copper (0.25mm) from a hobby store and making a head gasket out of it will help on power, it doesn't look like much but at half the thickness of the OEM gasket you will get more compression. i have remade all the gaskets on mine and am topping out at 33mph (with the 25mp gear installed). I plan on testing it out with the 30mph gearing this weekend to test its hill climbing ability. Properly lapped a head gasket may be unnecessary at all.
Again, once you have gone the free and cheap routes you will likely need to upjet.
You can machine the cylinder to a bigger bore, essentially increasing swept volume and effective cc's of the engine. To do this you will need to find a matching piston of increased size, probably 20-30 bucks and a machine shop, I'd priced one for my other 4 stroke 50cc at about 50 cheapest. About the biggest I think you can go is around 0.5 mm however so that'll get you not even a 5cc boost, but you may still notice a slight increase in power. This may be an interesting opportunity to investigate other slightly larger 4t pistons, like from small dirtbikes, to see if any exist with the same wristpin size and height but bigger bore.
You can also machine the head down so the piston comes closer to the top, increasing compression. That'll give you more torque off the line and if you know a guy it's maybe only 20 bucks plus another 20 for new gaskets (or cut your own gaskets).
A bigger carburettor will also let more flow. This is best coupled with opening the exhaust out. Plus you could adapt a tunable carb which you can actually find jets for.
Like a car, you can experiment with changing out to a more aggressive camshaft that holds the valves open longer, this can radically improve performance but you'll have to have the camshaft specialty made which would cost around $200-400 dollars and it will also put massive wear on your engine and probably ruin the valves within a few hundred miles. Fortunately they're pretty easy to replace if you do go that route. You can also mess around with porting and polishing the intake and exhaust for maximum flow similar to stock car race tuning. This requires a lot of knowledge and study or an experienced tuner and would probably run you a few hundred too, and even at best would likely only give relatively tame results. Oversized valves may be possible to fit. measuring for compatibility some dirtbike or scooter heads may be modified to fit also.
You can swap out cranks and cylinder but you'll have to machine the case to match it. You could potentially rig up some sort of variated transmission by machining parts and fabricating a mount for a Honda Hobbit or Vespa Ciao rear wheel.
- Here's a thread from the forums overflowing with Indian AMI-50 Chief informational goodies.
- Indian Dealer Service Manual (pdf)