what did you do to your motorized bicycle today?

GoldenMotor.com
Jan 21, 2015
610
25
18
Portland, Oregon
I've been working on my new project MB for the past couple of months.

I'll post pics and share more.

I was installing a Tanaka 47R, ala mid-frame and shift kit.

This morning, the Tanaka is out, making room for TWO pocket bike engines!!

Mid-frame twins with shift kit!.weld

View attachment 85468
Hmm... Looks unnecessarily complicated (I'd just use a bigger engine lol), but interesting and will be a good challenge. How big are those engines?
 

5-7HEAVEN

Well-Known Member
Aug 2, 2008
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Necromancer, to each his own.

These are new old stock 47-49cc pocket bike engines I had laying around for 10 years.
I bought the prettier one on Ebay. It was a custom engine someone built, but never ran. It has an adjustable carb I like. I ran it for a few miles, then it quit. I think it's the spark.

I could chain each engine a straight shot to the bottom bracket(BB).
The first engine sprocket, one chain to the BB sprocket. Done!
The second engine sprocket, another chain to its own BB sprocket. Done!
The freewheel on the pedal arm links both BB sprockets. One chain ring sprocket links to the 8-speed cassette. Done!
If I'm lucky, the chains and sprockets will be spaced 20mm from each other, and line up behind a single chain guard.
Right now, I'm using a 203mm(8") sealed bottom bracket. I hope I don't need a wider one. The next step up is a 330mm(13"!) unsealed unit.
I guess I could trim it down to 10" or so.

One extra hand grip throttle on the handlebar.

Orrr, I could run a jackshaft. Both engine chains converge there. Then a single chain runs to the BB.
The problem is that pocket bike engine sprockets are T8F chain-style. They have 6-spline pinion shafts. T8F sprockets are small, especially the tiny 11t drive sprocket. The #25 sprockets are teeny-weeny. However, they get the job done. If not, the pocket bike industry would've swapped out to bigger chains and gears.
I could not find T8F sprockets that slip onto any conventional 1/2" or 3/4" shafts.
And I don't feel like having a 6-spline 13mm shaft fabricated.

I think I need to create a new thread in DIY section on this.
 
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Dan

Staff
May 25, 2008
12,765
115
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Moosylvania
I've been working on my new project MB for the past couple of months.

I'll post pics and share more.

I was installing a Tanaka 47R, ala mid-frame and shift kit.

This morning, the Tanaka is out, making room for TWO pocket bike engines!!

Mid-frame twins with shift kit!.weld

View attachment 85468

https://motoredbikes.com/attachments/04-22-bicycles2-png.76418/
Purty cool, 5-7! Got that funky Frankenstein, Rube Goldberg sort of look.

Trying to imagine what the sound is gonna be like? Ya gotta post a vid.
 

Dan

Staff
May 25, 2008
12,765
115
48
59
Moosylvania
Made me think of the Joni Mitchell song, Dave. "Twisted"
(oddly, goes threw my head a lot, snork)

https://www.youtube.com/watch?v=iisYw0epV_Q

"...and we all know that 2 heads are better than one"

------------


Really looking forward to the new forum software! Would show the vid b4 clicking on it. Saves time if ya have a slower computer/device and don't have to wait for it to load. I'm on an old back up to the backup computer and it's so
 

5-7HEAVEN

Well-Known Member
Aug 2, 2008
2,661
240
63
Purty cool, 5-7! Got that funky Frankenstein, Rube Goldberg sort of look.

Trying to imagine what the sound is gonna be like? Ya gotta post a vid.
When twins are running, it sounds like a swarm of bees.
It was AWESOME!dance1

Once I had front friction drive and rear chain drive with different gearing.

Same engine, and they both had the same expansion pipe.

If both engines were idling, I'd sometimes start off on one engine. When I got to 15mph, I'd release the throttle on the running engine on the front wheel, then floor the idling engine on the rear engine!

It sounded EXACTLY like a single engine with a 2-speed transmission!
That was neat, but NOTHING beats the drone of twin engines. You hear the same drone on twin-engine commercial airplanes.
 

DaveC

Member
Jul 14, 2010
969
1
18
Boise, ID
When twins are running, it sounds like a swarm of bees.
It was AWESOME!dance1

Once I had front friction drive and rear chain drive with different gearing.

Same engine, and they both had the same expansion pipe.

If both engines were idling, I'd sometimes start off on one engine. When I got to 15mph, I'd release the throttle on the running engine on the front wheel, then floor the idling engine on the rear engine!

It sounded EXACTLY like a single engine with a 2-speed transmission!
That was neat, but NOTHING beats the drone of twin engines. You hear the same drone on twin-engine commercial airplanes.
I don't know about twin engines so much but I do know my roomies twin cylinder Harley sure has a "drone" when he idles against the house to warm it up....
 

xseler

Well-Known Member
Apr 14, 2013
2,886
151
63
OKC, OK
I had a very productive day! I adjusted the inboard pad in my disc caliper.



Really.


.....And just placed an order to "That's Dax" ---- damn this addiction!!! .weld
 
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5-7HEAVEN

Well-Known Member
Aug 2, 2008
2,661
240
63
I'm riding to work this week(12-mile round trip), so I thought I'd do some maintenance and repairs on my bike, Snow Tiger. The fuel line had ruptured several days ago, and I finally found time to replace it.
It had rained several times last week. Even though my wife had covered Snow Tiger, I was surprised to see how much oxidation there was on the bottom bracket, kick stand, sprockets and chain. So I wiped my bike down with WD-40 and oiled its chains and sprockets.
When I pushed my bike around, there was an annoying squeal coming from the front wheel. This occurred as Snow Tiger rolled forward or backward for the first few inches. When I wiped down the front disc with WD-40, the noise went away completely. I decided to clean the rear disc too, then remove as much residue of the WD-40 as possible.
While adjusting my brakes, I noticed the rear brakes needed its pads replaced. I'll order new ones.

After pulling maintenance, I gassed up Snow Tiger and pedalled to the nearby park. Whenever the tank and fuel lines ran dry, Snow Tiger had a hard time starting up. If my bike had its OEM saddle tank, I wouldn't have had this problem. The issue is that the 4-liter Peanut tank was mounted far away from the engine. The fuel lines and filter was also below the carb level. Gravity's working against Snow Tiger here. After a few pulls, fuel entered the bike's large automobile-size AC fuel filter. However, the Tanaka 47R engine still could not suck the gas up to the carb. The filter was midway between tank and carb. I disconnected the fuel line at the filter inlet and propped it above the carby. After a few pulls, Snow Tiger roared to life. I killed the engine, reconnected the fuel line and yanked the pull-start. The Tanaka engine fired up and away I rolled.

At the park, I tested my bike's ability to climb up the grassy knoll. If it stalled, I'll adjust the carb's "L" needle. Then I rode out of the park onto a long stretch of road. It's on a slight incline, a good place to tune Snow Tiger's high end. If needed, I'll pull over and adjust the "H" needle.

Everything checked out okay. The bike had no low or high-end issues. I rode to the bottom of a steep hill, cruised in and out of the mini-mall, then motored back to the hill's base. This was a good place to see how Snow Tiger pulled up a medium-size incline that's several hundred yards long. My first gear is very low(113-tooth), so I tackled the hill in second gear(87-tooth) from a stop. Snow Tiger pulled without hesitation. I'm very apprehensive about shifting under load while riding uphill. This is especially if I skipped every other gear. After slacking the gas, I shifted to 4th(67-tooth), waited 3 seconds, then rolled onto the throttle. Before I reached the hilltop, I carefully shifted into 6th gear(50-tooth). Snow Tiger pulled uphill without lugging, at half-throttle.

My bike was running perfectly.dance1

It's 5am. Soon I'll ride to the store and get some gas, oil and a new spark plug for Snow Tiger.

I can't wait to see daylight.
 
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5-7HEAVEN

Well-Known Member
Aug 2, 2008
2,661
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63
My Chinese helmet cam arrived in the mail yesterday.

Hopefully, I'll have it mounted soon and make some videos to post here.

It's 63 degrees and raining. Man, it's cold!

I'll stay inside and work on my camera until the weather clears.
 
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crassius

Well-Known Member
Sep 30, 2012
4,032
158
63
USA
for them as may be wondering about the new avatar, after my last birthday I'm so old that that is an actual photograph : (
 

xseler

Well-Known Member
Apr 14, 2013
2,886
151
63
OKC, OK
Well, the old saying "One thing leads to another." is exactly true.

Was doing something simple --- rigging a mount for a handheld Magellan GPS. Easy, peazy. Went for a short ride to test.......long story short, the clutch gave up the ghost. Started like it always does, went a few blocks, and the trouble soon began. At least I was close to home! Parts ordered.
 

Dan

Staff
May 25, 2008
12,765
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Moosylvania
Side note, Xman. Been working on thing for bikes I want to develop as a product. It's a sort of dashboard to hold a cell phone and depending on want, also a solar batt/charger. They have some really cool apps that work as Speedos, GPS etc.

But if you would field test one for me? Just measure what you'd like it to hold. And pm where to send it to ya. If ya have the time.

Eric, our new host, is testing one for me right now. (nice guy!)

I'm making em one by one so any size you'd like. Made one for a tablet. Man, it looks silly on a bike.

I just ask that you abuse it and offer brutally honest thoughts on it. I'm making em out of aluminum diamond plate. Looks pretty awesome on dark bikes. Your' S is black, yes?

But lemme know and thanks either way.