Electric mini-Harley gets an engine

[Krustalien]

Hi all,

I was given a Chinese mini-Harley type thing. It had a 500W 36v scooter motor (which still runs) but the whole thing had been through some tough weather and use. It might be possible to resurrect the batteries but I doubt it, they're reading very low voltages.

With that in mind I intend to put an engine in it. I have a 166cc 2 stroke waterpump motor, which I believe to be around 7hp. Stock max. rpm is 4500.

It won't be easy, as I don't have welding skills, but I have lurked on this forum for years and build battlebots for a hobby, so we'll see how this goes.

Intention is to run a regular cent. clutch (will be difficult to attach to the engine, the shaft is weird) to a jackshaft, mounted where the old motor went, then from there to the rear. At this stage I don't want to go much faster than 30mph, so I'm going for 5:1. I'll leave the path open for a TC and engine mods in the future if I want more grunt and speed.

Pics are of how the bike came to me, it stripped down, the engine that's going in and the engine in a mocked up position in the frame. I have other pics so if anyone wants anything in particular, let me know.

Wish me luck, and anything that comes to mind looking at these pics, please share, I am most definitely a noob!

Thanks,
Ellis

 

[landuse]

Nice project. You might want to gear a little bit lower though. I think 5:1 might be too high for a minibike type project

 

[Krustalien]

You may be right, I'll think about it. ^

Bit of a dilemma here. This engine is nice, and I'd very much like to use it, but the shaft it has is giving me a headache. Picture below. It's 5/8" or 16mm (would have thought it'd be metric but it does seem to be 5/8" when measured). Best case would be to step it up to 3/4", as I can then use any clutch system I please.

I had pictured taking a 3/4" or 19mm OD tube, cutting a slot in it, then carefully welding that to the shaft. Forgetting the complication of finding the perfect inner and outer dia. tube, I'd still need to get a keyway cut deeper in the existing shaft, and that requires a mill. I have no knowledge of a machine shop anywhere near me.

Alternative is to whack a sprocket on it with a massive setscrew (or two) and putting a clutch elsewhere. This complicates the build and closes future doors for upgrades.

Stepping up to 1" would seem logical if only 1" bore clutches didn't cost the whole world!

Any suggestions appreciated.

Edit: would anyone expect a clutch with setscrews alone to attach it to work, of course with big flats on the shaft so they literally cannot slip? Question is whether the clutch "hub" bit itself would be happy with that.

 

[mckutzy]

Well you have a good start for parts. You(Im thinking) might have to get a new motor, it might just be a pain to get a new crank shaft.

100$ for a new motor that has a proper shaft, is about good as it gets, Its also about the same size.

 

[Cole Tallerman]

http://www.bmikarts.com/Max-Torque-Clutch-35-58-Bore-_p_723.html

 

[Krustalien]

Getting a new crank with a usable shaft for this weird motor would indeed just be a pita. I live in Spain (for build projects that sentence is definitely followed by "unfortunately") and you simply cannot buy brand new industrial engines here, or not for a reasonable price. This engine is pretty much completely useless as it is, so I guess I'll try and mod it to make it useful. If that fails I'll dig even deeper and see if I can get a 6.5 clone or similar.

Cole, I have already thought about that size bore clutch, but it doesn't help me much. I still can't attach it even if it slides over the shaft nicely.

--------

Am thinking a combination of a weak keyway (but a keyway nonetheless) formed by welding a 3/4" tube collar around the shaft with a slot in it, weak because it wouldn't be very deep, and major setscrews might be the way to go. Probably would be able to dremel out a bit of depth to make it stronger too.

Thanks.

 

[DeathStarr89]

A machine shop should be able to cut a keyway in that crank for you.. after that then a 5/8 clutch should work fine.


I'd also have them drill and tap the end of the crank so you can run a retainer bolt with a big washer for safety.


Cool project!

 

[digschopper]

Aren't 2-strokes run with the shaft to the right?

 

[Krustalien]

Hey all,

This project has taken a bit of a turn in the past few days. After rolling the original chassis down a hill or two, it became apparent that in that form, it steered like a boat. Turning radius was horrible. Wheel to wheel it was long.

I knew keeping the swingarm would make for chain tension problems later on, and none of it seemed very tough anyway. So in a burst of inspiration we stuck the rear wheel into the mounting tabs for the swingarm. Bingo!

So I made up some axle plates that position the rear axle an inch or two back from where you generally sit, which helps with the tendency to wheely. Pics below.

The same day saw most of a new seat get made, all unnecessary tabs and mounts for the original bike (lights, plastics, etc) get removed, and the engine mount plate get bolted on. Today we mostly freed up the front forks (handlebars will be changed) as they were rusted to hell, and finished the seat. The engine is not yet mounted, only mocked up.

I/we cannot weld, once we get things finalised we'll get whatever needs to be welded done by someone who knows what they're doing.

Looks a bit different now huh?

Ellis

 

[landuse]

I prefer it the way you have it now. You will be much happier that way. I think it is looking great.

Just one question. Those "axle plates", are they made of aluminium?

 

[Krustalien]

Nope, they're steel. 3-4mm, can't remember. Old combat robot armour offcuts.

And yeah, it steers way nicer now, feels a lot less lumbering, which is precisely why we shortened it.

Finally got rid of the original handlebars , replaced with some simple bicycle ones, making it a lot more comfortable. I have sourced a 420 50t bike sprocket and chain in my town which is great. I'll order the clutch today. Bit worried about how we'll get it on the engine but we'll find a way once we have it in our hands.

Also, said build partner thinks the current black and chrome as it is now, with in-your-face green details? Thoughts?

Ellis

 

[philip metzner]

If your real handy with a dremel you can use a cut off wheel and cut a key way in the crank. I have done it with no problems, even if it aint perfect. Practice on some scrap first.