The Jura Big Fifty build, evolution, repair and a-ha moments

So I said howdy, now's when I share the good stuff (and the bad stuff too).

In 2016 I built the Jura Big Fifty, using an Electra Cruiser 1 and a Bikeberry 49cc 4-stroke kit. This is what it looked like right out of the barn:
DSC00341.JPG


And of course there were problems. First I couldn't get the coaster brake to work. Felt like it was slipping. So in spite of it being brand new, I rebuilt and adjusted it. Got real good at rebuilding and adjusting coaster brakes. Still no go. Then I decided that the coaster just wasn't up to the task of stopping 300 pounds of bike and rider, even with the Sturmey front drum helping out, and ditched it. Got a new rear hub from Bikeberry/BBR that uses a thread-on sprocket and comes with a thread-on band brake.

The sprocket and hub was a wonderful upgrade. The Bandbrake was worthless. Worse than the broken coaster brake. Then the transmission input shaft broke and I had to pedal home. That's when I had the first a-ha moment. I had slip in the pedals while pedaling forward, too! Turns out the problem wasn't in the coaster brake, but in the wide crankset. The sprocket is pressed onto the shaft, and none too tightly. Hit it with the welder (just a couple tacks) and that problem was solved. But now I was stuck with this useless bandbrake, or so I thought.

Finally did something about it when I found a thread-on disc brake adapter. Bought that, a Tektro mechanical brake, made a mounting bracket and welded it to the chainstay. It barely misses the sprocket, and wouldn't miss the chain if I tried to mount it elsewhere. Sorry it's a little hard to see.

DSC00513.JPG


I'm sure you noticed the chain's off. More on that in a moment.

The brake cable was way too long, and I almost cut it but then had another a-ha moment. The extra cable goes into a piece of 3/16 brakeline (or a noodle if you want to use bicycle terms) and up under the rear rack, where it attaches to an ATV brake light switch. So now I have a real brake light (a GOOD one, that uses a real 1157 bulb, not LED's). Picked up the switch and lamp on Amazon.

So the wheel's not orange anymore, what's up with that? I changed the front to a 24 to match the rear, and the ride is a hell of a lot better now. And since the new rim was black (Odyssey Hazard Lite, way overkill but a really nice rim) I changed the rear to black as well. Looks better to my eye. Re-used the Sturmey-Archer drum in the new wheel.

DSC00509.JPG


Tires are Duro Beach Bum 24x3, with the decals buzzed off. Want to know what really burns me about these tires? The sidewall molding doesn't say Beach Bum, it says EACH BUM. Really, Duro, really? Other than that I really like 'em. A soft ride and nice feel overall.

With more rubber on the road and really good brakes now, I can stop from 25 mph in about 40 feet. Good thing I put a brake light on there.

So guess what happened yesterday?

DSC00511.JPG


Yeah, the damn input shaft sheared AGAIN, in the same place, My armchair analysis tells me this is probably machined from the cheapest Oriental bar stock they could find, and there's a nice stress riser right where it sheared off, since the other one broke in exactly the same place. My thoughts yesterday were to get a new one made by a machine shop, out of decent steel this time, and with a radius to eliminate the stress riser. But you'd still be pushing 2 HP through a tiny shaft. Might get away with that if you made it from titanium, but I'm not confident in that. So I'm ditching the 5G gearbox for a Grubee belt drive, which should arrive in a week or so.

One last pic, the bike as it sits today:

DSC00510.JPG


In this pic you can see the battery that runs the lights, the brace for the engine to the top tube, and the PMS (Puke Management System). What's the PMS all about? Well, the HuaSheng crapped the bed after about 20 miles of riding. It had so much blow-by that oil filled the chamber above the crankcase and got pushed up to the air filter. It would leave a puddle wherever it went. This engine isn't a HS, it came from a friend who gave up on it. It's another Honda clone. The only identification I can see is a pad that says BRAND. It runs a lot better than the HS ever did. So the PMS isn't needed (yet). It connects to the engine's breather outlet and separates out the oil from the air vented to the atmosphere. So far all it's caught is water vapor.

Stuff you can't see: A handlebar mounted light switch and key switch, wires routed thru the handlebars, memory foam grips, gel seat, lots of good stuff that makes the bike a real joy when it's actually running.
 

26insh

New Member
Joined
Dec 8, 2018
Messages
2
awesome build but how did you get the "moped" plate? Did you have to get it inspected? My Wildfire is plated but its on the "approved list"


J
 

Old Busted Hotness

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Joined
Jul 2, 2018
Messages
407
Nope, just showed up at the BMV. Had a little bit of what's the VIN-there is no VIN-but what's the VIN-there is no VIN-let me get my supervisor but it went thru in the end.

For a motorcycle plate, it WOULD have to be inspected by the highway patrol and they'd issue a VIN. But then they'd want it to take an emissions test, and it would have to have OBD-II to pass that, and I don't know how the hell you'd get OBD-II to work with a carb and magneto. In the end it was more realistic to plate it as a moped, because that's what it is.

I found a sidewall bubble in the rear tire, so I replaced them both. Never knew you could get a bubble in a tubed tire. Turns out the rubber around the wire bead is super thin (thanks Duro) and it parted. Then the plies started to separate. No way I'm riding on that, so I upgraded to Felt Thick Bricks. Really hard to find tires in 24x3, especially if you want whitewalls.
 
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Old Busted Hotness

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Joined
Jul 2, 2018
Messages
407
Man, I thought I had a kickass idea: Cheap-ass Amazon kick-start lever mounted on the pedal shaft going to the rope starter. Many problems (starting with just getting the right-side pedal off). Kick-starter lever spun the pedal shaft a little, not too bad (I greased the hell out of it) but it was too easy to get tangled in the pedal. Lift the bike and move the pedal, an aggravation but not a deal breaker. Hard to get enough velocity to actually start the engine, that's a deal breaker. And the rope failed while I was trying, that's two and a half deal breakers. Oh well, it was a good way to kill time on a holiday morning.
 

Frogslayer

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Joined
Jan 20, 2019
Messages
2,576
Kick start on the pedal shaft that pulls the recoil rope? Man your herb must be better than mine lol. Nice bike man. Thanks for all the wonderful pictures and truth of what worked and what didn't. That Springer fork looked so cool but if you don't feel safe riding it you need a huge desk for a paper weight that big. I'm glad you went back to the other forks and kept at it. I imagine a four stroke with belt drive is as smooth as it gets. Besides electric of course.
 

Old Busted Hotness

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Joined
Jul 2, 2018
Messages
407
Here's Springer 2.0, a Sunlite Deluxe I found on Amazon. Pricey bastard, and here's why: It's built right.

DSC00592-1.jpg


For starters, it weighs about twice as much as the ebay special. That alone inspires confidence. All the components are about twice as thick and it all has a much better quality feel to it. And:

DSC00593-1.jpg


There's plenty of room for my fat tire. No more worries about rubbing. I replaced some of the spacers with rubber hose for some rebound damping. The top bracket clamps onto the steerer with a beefy Allen screw, so it stays put. FYI, if you're buying one of these be advised that they have a gorilla torque that screw down at the factory. Also, the steerer tube is really long, with lots of thread. Even on the long Electra frame, I ended up cutting off 4 inches.

DSC00595-1.jpg


Here you can see how thick the rockers are. The brake arm mounts right to the suspended fork, so there's no more rebound action when braking.

So I got it cut to size, mounted the wheel and bars and went for a test ride. SUCCESS! The wheel doesn't wobble, it's a dream over bumps and corners with confidence. Lesson learned, you buy cheap, you get cheap.

Then I added some padded leather grips:

DSC00596-1.jpg


What is it about leather and motorbikes? They just go together. Sorry it's so dark in my cave.

Still deciding whether or not to mount a fender, and how.
 

Spare_Parts

Well-Known Member
Joined
Nov 29, 2017
Messages
2,017
That is a nice fork. Like how the wheel bolts ro the suspended fork. Now we need some outside pics of the bike.
 

curtisfox

Active Member
Joined
May 13, 2010
Messages
612
Sunlike is a good fork, been around a while, then cheep ones come along. Made a bad name for springer forks, welds breaking. Glad you got this one, should be good for long time, and stabil also.........Curt
 

gary55

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Joined
Nov 27, 2012
Messages
4,048
Here's Springer 2.0, a Sunlite Deluxe I found on Amazon. Pricey bastard, and here's why: It's built right.

View attachment 87133

For starters, it weighs about twice as much as the ebay special. That alone inspires confidence. All the components are about twice as thick and it all has a much better quality feel to it. And:

View attachment 87134

There's plenty of room for my fat tire. No more worries about rubbing. I replaced some of the spacers with rubber hose for some rebound damping. The top bracket clamps onto the steerer with a beefy Allen screw, so it stays put. FYI, if you're buying one of these be advised that they have a gorilla torque that screw down at the factory. Also, the steerer tube is really long, with lots of thread. Even on the long Electra frame, I ended up cutting off 4 inches.

View attachment 87135

Here you can see how thick the rockers are. The brake arm mounts right to the suspended fork, so there's no more rebound action when braking.

So I got it cut to size, mounted the wheel and bars and went for a test ride. SUCCESS! The wheel doesn't wobble, it's a dream over bumps and corners with confidence. Lesson learned, you buy cheap, you get cheap.

Then I added some padded leather grips:

View attachment 87136

What is it about leather and motorbikes? They just go together. Sorry it's so dark in my cave.

Still deciding whether or not to mount a fender, and how.
I like the sunlite springer forks. Looks like you got both bushings abv. the top bracket. Might wana try it like this. Nice bike.
View media item 60781
 
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