Weed Eater mini bike questions

[5-7HEAVEN]

How long do you think the clutches on those tanaka will hold up?
Again, my small engines (22-30cc) builds will be on the 15:1 ratio MINI MINI MICRO bike. Should I buy a spare clutches incase? Lol. It'll mostly be ridden by 50lb-150lb riders ,but guaranteed stepdad will be all over it. He's 250 or so. All terrains will be dirt and gravel...

Excessive heat that kills clutches are caused by :
1)High gear(lower numerically)with minimal pedalling;
2)High gear w/steep hills and minimal pedalling;
3)High gear with heavy weight and minimal pedaling.
4)High gear from a dead stop and minimal pedaling.

From my experience, Tanaka engines w/76mm clutches have zero issues on anything, period. They have a very large single spring and two large clutch pads. Unsure of other Tanaka engines. I imagine the same level of dependability.

Be advised that weedwhacker engines (even a Tanaka) have a very light load and tiny clutches, for what they're expected to perform. That same engine mounted on a bicycle encounter much more mechanical stress and higher levels of performance.

A 15:1 ratio is not easy to achieve with only two sprockets or pulleys. The largest easily-available sprocket is an 80t w/25mm chain. That's 13.333:1 gear ratio w/a 6t engine sprocket, like 34.67:1 on a 26" bike.
Try a 6t engine, 80t wheel sprocket(6.49" diameter) w/25mm chain.
17.8mph @ 8,000rpm
Then you simply and easily swap the engine sprocket to 7t(11.429:1) or 8t(10:1) for more speed/less low end.

 

[2StrokeMama]

Non of these bikes will have pedals! The only bike of mine that has pedals is my actual motor assisted chopper with the skyhawk.
- that sounds like a good plan tho! I appreciate you working those numbers out for me. the 15:1 ratio , as I wondered If that large of sprocket would even work.
My apologies, what do you mean by "OT" when referring to the drive sprocket? How many teeth would "8ot" be?
Thank you for the help!

 

[5-7HEAVEN]

Non of these bikes will have pedals! The only bike of mine that has pedals is my actual motor assisted chopper with the skyhawk.
- that sounds like a good plan tho! I appreciate you working those numbers out for me. the 15:1 ratio , as I wondered If that large of sprocket would even work.
My apologies, what do you mean by "OT" when referring to the drive sprocket? How many teeth would "8ot" be?
Thank you for the help!

LOL, sorry, I mean eighty-tooth sprocket. Keyboard error.

If no pedals, then gears need to be super low with small engines.
A 15:1 or lower ratio would work better, especially with no pedals.
You must use sprockets w/25mm chain. Any larger chain (T8F, BMX, #35) would have sprockets almost as large in diameter as a 10" rear wheel.

Here's an 89-tooth sprocket:
http://www.electricscooterparts.com/sprockets25chain-wheel.html

The 89t will bolt onto a left-hand or right-hand freewheel. Its gear ratio w/6t engine sprocket is 14.833:1

 

[Street Ryderz]

I have loved bikes of all types my whole life and my youngest is the same,Since he was 5 y/o he's been on a pocket dirt bike it's well suited to a 5 y/o but thats it! my nephue a few years back but a full grown adult 175-180 lbs just going fast thru a dip in the terain snapped the cross member thats holds the top of the mono so called shock clean of the frame when I went to fix it the square tube used had a wall thikness of I swear two peices of paper so I welded the mount to some square tube that had about an 1/8" thickness and that has held up well!you can see it in the pics It's the blue 2010 daymack 49cc he loves this bike even still this even when he saw that I had it out he wanted to go for a rip Lol no joke!I had already been doing repairs for these,scooters,mb's and anything with a small motor at that time and I picked up this wasp 49cc this pocket dirt bike was unlike any I had or have ever seen the frame is thick wall good dia steel the wheels are steel It has old drum brakes that just never seem to fail it has a real mono shock that holds my weight no issues and has a three gear gear reduction case that has worked perfectly for many years now and still does power wheelies all day again even with me on it!I will post a video of some wheelies and you will hear the throttle response it's crazy!netheir one has any after market parts or any thing just jetted and set up well for what they are just for fun!

Here's some video of the wasp!

 

[Street Ryderz]

Non of these bikes will have pedals! The only bike of mine that has pedals is my actual motor assisted chopper with the skyhawk.

I would like to see your chopper as I've built a few ! The up right riding position for traveling any distance suits me better than hunched over!And I swear the longer wheel base is smoother.

 

[peter612]

My first motorized bike was a Grubee Skyhawk. It went together as the directions implied.
It ran for 1500 miles of experimentation and high reving speeds and modifications.
A wristpin circlip failed from hours of 10,000 rpm. Imagine if I rode it as intended?

You friction drive guys, you're always rubbing your tires!

Seriously 5-7 Heaven, that TANAKA trimmer looks like a great tip. They are a very good motor.
Now about all this tire rubbing...

OTH, chunky chinese MTB tires are sub $10 ea & easy to swap. Usually rear tire, & grip not a big deal at the back. Allow that it also serves as a "non wearing" clutch.

Friction is understandably maligned, but once the dark art part is mastered, there is a lot to like. Tire pressure needs to be exact, for optimum spindle grip e.g.

 

[5-7HEAVEN]

OTH, chunky chinese MTB tires are sub $10 ea & easy to swap. Usually rear tire, & grip not a big deal at the back. Allow that it also serves as a "non wearing" clutch.

Friction is understandably maligned, but once the dark art part is mastered, there is a lot to like. Tire pressure needs to be exact, for optimum spindle grip e.g.

There was a time when I had twin Mitsubishis on friction drive on my bike.

Mama, now I'm building twin pocket bike engines on chain drives with a shift kit.

 

[2StrokeMama]

BRAP BRAAAAPPPP LOL that things awesome it actually sounds like a dirt bike. The chopper I have is a little buried at the moment... tho I didn't build this bike myself. It was actually given too me from my neighbor, because when I moved up here he noticed I was outside working on bikes all day , at home with my daughter. He decided to give it to me to clean and fix up. It's not a project, just needs to be cleaned out. It was given in winter when I was started my BBK upgrade on my scooter, so I was already a bit occupied with that.

 

[2StrokeMama]

There was a time when I had twin Mitsubishis on friction drive on my bike.

Mama, now I'm building twin pocket bike engines on chain drives with a shift kit.
View attachment 76418 View attachment 76419

WOW, that's very impressive. I'm not sure if I'll ever get to building a bike with more than one engine. Let alone a micro bike with 2 sets of gears lol. So I suppose, that setup would be somewhere around 6horses?

 

[5-7HEAVEN]

Six hp is a good conservative estimate.

I had ADA expansion pipes on my Mitsus. My friction bike also had around 6hp.

You can REALLY feel the extra torque when punching through stiff headwinds.

My bike has 8 speeds. I'll prolly use 3rd, 5th and 7th most often. First is for crawling, and second is for climbing berms from a standing start.