My 20's Style Touring Build

First off sorry for a new thread but the old one was cluttered and OT.

First a quick overview of my build- if you are not interested just skip to the questions (I do need help on these please).

First pic is of my build at the moment.

I used a standard, mid-size 26" rigid ATB frame, stripped of stickers etc. Rear wheel was trash and went to the scrap yard. Front wheel is a decent aluminum/ steel spoked assembly and will stay on the bike.

Brakes: unknown as of yet

Wheels: unknown as of yet

Seat: Vintage Viscount springer (makes it look like an old BMW R36 seat, look it up)

Bars: Chrome risers for a comfortable ride

Pedals: Made to be a copy of "starter pedals" used by motorcycles of the 10's and 20's, using a tiny front sprocket and large rear sprocket the ratio isn't good for much over 2 mph but works great as a backup starter and gives it that vintage look.

Motor/acessories: 2-stroke 68.5cc slanthead kit, "silver" paint job that looks okay, using kit clutch and brake levers, grips, electronics, tank, etc. Has pullstarter.

Gear: Large rear reflector, hillbilly-made headlamp (turn signal case from an old motorcycle, sawed off the rear cap, inserted a cheap LED flashlight, clamped the light to the case and used some scrap aluminum to mount to the bars), Bell toolbag with full toolkit, rear rack with 2 gallon spare gas can, motorcycle mirror off a Honda CB350, walmart digital speedo, standard tires and tubes.

Question: Would an external gearbox, Non-jackshafted, work on of these china motors? Here's my idea (See 2nd and 3rd photos for my dummy setup): Using a flipped front derailer from a bicycle, right under the motor's lower chain output. Put a lower sprocket such as a 44 or 48 in the derailer's lower gear position, and a higher sprocket like a 36, 38 or 40 in the derailer's higher position. I already thought about chain alignment but a properly spaced 2-speed shouldn't do too bad (let me know if otherwise of course). See pictures for true detail.

The goal of this whole thing is to put together a 2-speed gearbox for the stock China kit that is cheap and can be made using regular bicycle and hardware parts. 2-speeds is just right for these motors, one to start off in/hillclimb and one for cruising. That way 30mph is doable calmly and the clutch won't fry every time you take off from a stop. It would also work for stock HTs, make things a bit more universal and make the list you tell a new MBer to get easier, ie motor kit, lights, trans.

Would really like some input on this, again see 2nd and third pics for the dummy setup.

Would a tensioner possibly work as an idler? Was thinking spring loaded but that would flip the chain off when shifting- maybe, if I am wrong a spring-loaded tensioner would be perfect.

Still mulling your other idea over, hmm..

Update: Found a two-speed sprocket set from a 90's MTB crank. Removed the crawler gear and plastic protector and got a surprisingly sturdy 48t-39t sprocket set.

They are connected closely to each other and will be mounted on the wheel like a typical MTB's freewheel gears would be, except of course on the left side of the wheel and using the rag joint and bolt mounting system that comes with the chinese kit.

The diameter of the hole in the center of the sprockets is too small to fit on a standard wheelhub and will need to be made larger, the same size as the 44t that comes with the chinese motor. Would a machinist be required to do this?

Once the center hole is large enough, it will be fitted over the hub, mounted on the wheel and the issue of chain alignment and tension will be next. Some sort of spring-loaded tensioner would be necessary UNLESS the difference in sprockets (8t) is small enough not to require high tension and the stock tensioner can be used, putting a middle ground between higher tension (larger sprocket) and lower tension (smaller sprocket).

Ah crap... just found of my frame is misalinged, the motor chain leans to the right when mounted straight on the frame and measurements confirmed that it is about 1/2inch off balance. If I get a new frame and fenders I can't afford to try out the 2-speed setup. Although reading through the archives on here it appears 35mph is possible with a 44t, it was substantiated (videos by a senior member, not the "OMG 40MPH LOL11111" types). However, it does free up money for fenders! This could be a quite vintage build, maybe something like a 1910 Pope Motorcycle?

Alright that last post was rubbish. Sorry.

Okay, here is the situation now- I have switched to another frame and am still having problems with motor alignment. It leans to the left just slightly, and the bottom end of course has more acute lean making the chain somewhat out of alignment (when the chain is strung straight from the sprocket outwards, it points rightward at about a 15 degree angle).

I am not comfortable building it like this for many reasons, safety, power transmission and aestetics to name a few. Anyone else had this problem?? The frame I am using is very common, a typical hardtail MTB frame.

Help please, and thanks.

I did right before I closed up for the night, the chain bends a tiny bit. I don't know about the strength of these chains or the master links either, I will try to figure out a front mount mod tommorow, maybe that will fix it.

Decided to paint the frame today while it was apart, going for the vintage motorcycle look so I chose flat black.

I would highly reccomend Krylon Satin Black (indoor/outdoor). It went on well and gave a smooth flat finish. Painted the fork and it looks excellent.

I need to respoke my rear wheel, I have the spokes and new hub, but does anyone know if Sheldon Brown's tutorial on wheelbuilding is sufficient for a motorbike application? It seems pretty thorough but I had to close up for the night just as the rims were cleaned and prepared to be respoked.

Clutch arm question... while connecting the clutch cable to the arm, I see no way of securing the cable. Most of these kits have a small screw at the tip of the arm that secures the clutch cable, but this one just has a flat gap (the size of a typical flathead screwdriver gap) and no screw or mechanism to secure the clutch cable. How is this meant to work?

Secondly chain question, I have the tensioner set up so that the tensioner wheel is facing inside the frame, is this correct? It seems to work. The chain, from motor to tensioner to wheel, is not perfectly straight, the motor leans a tiny bit to the left, the wheel is probably a tiny bit out of true, etc. I don't want a teardown again, these minor variations won't kill me or the bike right? It seems I have seen too many haphhazard, "throw an unmodded china motor on a regular, unmodded bicycle" situations work out well, and they almost definitely had wheels out of true, badly mounted motors etc far worse then my situation.

Excellent... thanks mate. It's almost built and I am feeling like a kid on christmas.