Meet Stunner

[2door]

Fuel foaming, possibly? I used to scoff at that theory but it has since proven to be valid.

I built a bike for a friend and he had an issue similar to what you're describing. He brought it to me and I found all of his engine mounting fasteners were loose. (He's a rider, not mechanically inclined) Nothing broken but the engine was loose in the frame. After I torqued everything back together his bogging issue went away.

I have to suspect it could have been the fuel was foaming in the carb due to the extreme vibration. Nothing else makes much sense.

Tom

 

[biknut]

Since you put coaster brakes on such a nice bike it seems to me that your opinion of them is pretty good. (combined with decent front brakes of course)

When my cash flow improves I want to get rid of the rim brakes and go disc or coaster.
How would you personally rate coaster brakes for a motorbicycle?

I know that when I was a kid they always stopped me and seemed to last forever. What kind of lifespan can one expect on a motorized bicycle?

If I have my druthers, I'll always prefer a coaster brake, for 2 reasonds.

1. Since only about 30% of your stopping power comes from the rear wheel, a coaster brake has way more power than it actually needs for typical street riding. Downhill racing might be a different story, but I ride the street. With proper maintenance a coaster will never wear out. About the worst thing I can think of about using a coaster is, some of them don't have a lot of feel between hard braking, and total lockup. Not a problem for me though.

2. A coaster hub lends itself to a hub adapter.

 

[2door]

The only problem I have with my coaster brake bikes is changing from them to one without. Ride a coaster for a couple of days then get on a bike that doesn't have them and you find yourself pedaling backwards coming to a stop and suffering a moment of panic when instead of slowing...

Tom

 

[rdog422]

Fuel foaming, possibly? I used to scoff at that theory but it has since proven to be valid.

I built a bike for a friend and he had an issue similar to what you're describing. He brought it to me and I found all of his engine mounting fasteners were loose. (He's a rider, not mechanically inclined) Nothing broken but the engine was loose in the frame. After I torqued everything back together his bogging issue went away.

I have to suspect it could have been the fuel was foaming in the carb due to the extreme vibration. Nothing else makes much sense.

Tom

Thats definitely what it was. Its called cavitation, it can be caused by too much pressure from a pump, or excessive vibration. Its like how a boat propeller makes bubble even when completely submerged.

 

[Toadmund]

Thanks biknut.
My bike is not equipped for disc brakes (no mounts) and would require some fabrication, not only to add mounts, but also to fit in a disc (with 44T sprocket) is another matter altogether.
Coaster brakes would just be much easier to do

 

[maniac57]

I like coaster brakes if kept in good working condition and with a good front brake.
Just requires a different set of reflexes. Nothing wrong with old school.

 

[silverbear]

I like coaster brakes, but not all of them. I like the old Bendix especially. Open one of those up for a look at the bearings and quality of metal parts and then do the same with a Chinese coaster brake... fewer bearings and junk metal. Not all coaster brakes are the same. Japanese are better than the Chinese. Old German coaster brakes (Sachs) are very good. I've built several rear wheels with old Schwinn balloon tire rims, Bendix hubs and heavier gauge spokes. Makes a good, stout and reliable wheel. You can use a hub from a middleweight wheel just fine and lace it into a wider rim. Don't throw away your old wheels with Bendix hubs... salvage the hubs at least.
SB

 

[biknut]

You can use a hub from a middleweight wheel just fine and lace it into a wider rim. Don't throw away your old wheels with Bendix hubs... salvage the hubs at least.
SB

Good advise silverbear.

 

[Toadmund]

Don't want to go too off topic, but here we are.

What about new bendix coaster brakes.
Any other recommended brands?

What about those band brakes?

 

[silverbear]

I don't even know if Bendix is still making coaster brakes. My old ones are from the 50's & 60's A nice thing about them is that diagrams of the internals are freely available on the internet so when you've got things apart for cleaning and new grease you have a guide for putting it all back together properly. As for other brands, I would guess that just about anything old, say into the 1980's made in the USA, Canada, Britain or Germany (Sachs invented the coaster brake) would be of good quality. Things used to be made to last and bicycles were not throw-aways, but something handed down from sibling to sibling. I've had good luck with the newer Shimano CB110 hub from Japan. Bairdco knows more about this than I do. I've had poor luck with the Chinese hubs, having had two of them fail. After that I didn't use them anymore.
SB

 

[biknut]

I've had good luck with the newer Shimano CB110 hub from Japan. Bairdco knows more about this than I do. I've had poor luck with the Chinese hubs, having had two of them fail. After that I didn't use them anymore.
SB

I agree with this. I bought a new Shimano 110 that's on the Atomic BB. It's higher quality than the chinese hubs, and they only cost about $30. They also sell them to fit 14g, and 12g spokes.

 

[silverbear]

I agree with this. I bought a new Shimano 110 that's on the Atomic BB. It's higher quality than the chinese hubs, and they only cost about $30. They also sell them to fit 14g, and 12g spokes.

I'm not in a position to say which is better, the new Shimano or the old Bendix. What matters is that they're both good. What I like about the Bendix is that I find them on old bikes and don't have to buy a new one. Clean the old hub and give it new grease and it is good to go. Also the model which came out just before the red band Bendix (probably early 50's) is the same diameter as the CB110 so you can use the same size clam shell hub adapter if you go that route for mounting a driven sprocket. I discovered that by accident. If you lace the hub and wheel with 11 or 12 gauge spokes then you have to drill out the spoke holes on the hub to make the holes bigger. Not a problem. Doesn't take long to drill out 36 holes a bit. And save $30.00 to blow on something else. Ha!
SB

 

[Toadmund]

This one?
CB-E110

PS, dumb question, I am not ashamed.
36 spoke, 18 per side?

 

[azbill]

no such thing as a dumb question,,,
only dumb answers !!!

yes, 36 spoke hubs have 18 holes on each side

 

[biknut]

This one?
CB-E110

PS, dumb question, I am not ashamed.
36 spoke, 18 per side?

If you're thinking about buying that one, I'd ask the seller how many spoke holes it has. It might only have 28. It says 28H.

 

[biknut]

I just jetted Stunner down to a 62, from a 64. I started out with a 68, and have been leaning it out ever since. Off idle is now smooth for the first time.

I checked the plug before this jet change and it was pretty dark, so I don't think it's running too lean now, and it's running, and starting well like this.

I hope I'll see an improvement in gas mileage now, because I haven't been that impressed with it so far. I've only been getting about 80 mpg. I'd like to see at least 100 or better.

Other than that I'm very happy with how this bike is doing overall.

 

[2door]

What carb are you running, and do you know in drill size what your "62" jet is? I never use jet size because they seem to be arbitrary. I use a set of orifice drills and select my jet size based on them. For example I've been having good success with a jet soldered and drilled to .0225. It seems to be perfect for my altitude here.

By the way, good to see you weren't in the tornado's path.

Tom

EDIT: Everytime I look at Stunner, I like it more. Beautiful bike!

 

[biknut]

What carb are you running, and do you know in drill size what your "62" jet is? I never use jet size because they seem to be arbitrary. I use a set of orifice drills and select my jet size based on them. For example I've been having good success with a jet soldered and drilled to .0225. It seems to be perfect for my altitude here.

By the way, good to see you weren't in the tornado's path.

Tom

EDIT: Everytime I look at Stunner, I like it more. Beautiful bike!

I just have a bunch of store bought jets. I'm running a speed carb, which I believe is about 14mm. Plus a SBP pipe, and air cleaner. The rest of the motor is stock except for the shorty manifold.

I pretty happy with how it's running and don't even want more speed out of it. It runs 35-40 now, and that's faster than I should run it. I'm trying to get better low speed running is all. I noticed a few weeks ago when I rode about 20 miles on a bike trail that it wasn't running very well at ultra low speed. It 4 stroked, and sucked a lot of gas. I've been meaning to rejet it since then, but only now got around to it. Seems a little smoother now too.

And yeah that big wind was close. Too close, but my wife and I, and animal herd are all safe. Thanks Tom.

 

[biknut]

With the 62 jet I got about 90 mpg today. That's the best yet. I'm starting to think that's going to be about it. I did ride the first 15 miles wfo against a strong headwind. It's possible that if I keep the speed down to 25 to 30 I might be able to squeeze 100 mpg out of it. Today at least part of the time I was going over 35 mph. More testing is needed.

 

[biknut]

Stunner is working out to be remarcably dependable. There's only been a few problems since day one.

The nut on the pedal side sprocket came loose once. After that I used loctite on it, and don't expect that to ever happen again. This problem wasn't really my fault. i never checked it from the factory, because I never had a problem like that before.

My exhaust pipe broke because I didn't have a lower bracket on it. i added one to the new pipe, so don't expect that again. That was my fault, I should have known better.

Other than that I had a plague of magneto coils go out. I made 3 changes to stop that from happening again. I rewired the kill switch to open instead of shorting out the windings. I stopped running the spark plug gap so wide. Changed to 0.025" from 0.035". And I got rid of the resistor plug cap I was using. Knock on wood, I haven't had any trouble with that in a while. Probably my fault.

The only other thing was 2 screws on the rear motor mount vibrated loose. Loctite again. Probably my fault.

The motor starts good, idles good, and runs good. It still only has 451 miles on it though. I can also claim It's getting 90 mpg after last Sunday, and I've seen 40 mph max speed on the speedo a few times.