Absolute Fastest Motorized Bicycle YD100 Engine On Planet Earth! Nuked On C85 (50/50 Nitromethane)

user54508

Member
Feb 3, 2021
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This thing was pushed to the limits of it's existence! It was pretty much breathing fire at point it hits 70mph!
Background on this custom Ethanol build was to win a bet. But now that spent time perfecting this sucker. Running fully Dimpled intake and reed valve all fully bored to 20mm Pilot jet 65 and main jet of 260. E3-16 plug. I think is 27X hotter then NKG 6 plug like in more motorized bicycles. Custom made 3 ring Nickle coated piston. Running 50/50 @ 32:1 oil mix. We chose yd100 because of it's one piece and we wanted a legit motorized bicycle jug to build this. Yes I know we have many minarelli's and saws pigos now but this was not are goal! So enjoy the videos description has all the math and such to back up the claims and how we pulled this off with a motorized bicycle kit motor!
 

user54508

Member
Feb 3, 2021
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I'm curious how you calculated the speed?
I have an Answer! Math below comes out to 79.77 now in my video it says top speed of 75mph on GPS speed tracker. The 2 are pretty close to each other in end! math is in perfect world conditions and GPS is real time with environmental and situational effects on bike! get what I mean! but they come out close so you can test if one is bs or not is the point! many edit videos and stuff to make it look faster then the bike can mathematically go even! but math in this case actually even out preforms the post speed I showed on the gps! Basically to show it's not a bs video!


Engine Transmission gearing is (82:20T) 4.1to1 Ratio
Engine Rpm was 10,974
------------------------------------------------------------------------------------
10,974 / 4.1= Output: 2,676.5 RPM

Chain Pinion (8t) to rear sprocket(22t) 2.75 to 1 Ratio
-------------------------------------------------------------------------------------
2676.5 / 2.75 = Output:= 973.27

27.5inch wheel is = 12.2rpm per 1 mph
------------------------------------------------
973.27 / 12.2 = 79.77

Giving Us A: Top Speed Of ( 79.77mph)
 

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
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Also.... look close at the gear ratio charts you have posted... 30t / 60t gears are not 1:3 ratio!! (that's 2:1 ratio).

Think about it... the 30t gear has to spin 2X for the 60t gear to spin 1X (that's 2:1)


In conclusion... your math is all wrong.
You should try using a good GPS speed app (on your phone) instead. ;)
 
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Sidewinder Jerry

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Sidewinder Jerry

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Larry Trotter

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Nov 26, 2017
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To double your speed takes 4 times the power so if your stock engine makes 35mph on 5hp then it takes 20hp to get to 70mph. Any one getting 20 hp out of one of theses engines?
 
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Larry Trotter

Active Member
Nov 26, 2017
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This is really fun to read even knowing that a China girl engine has a snowballs chance in **** of touching 70 mph.
 

Sidewinder Jerry

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Dec 19, 2011
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This is really fun to read even knowing that a China girl engine has a snowballs chance in **** of touching 70 mph.
He also says in the comments that he's going down a slight hill. There's a fairly long grade in Strawberry Plains Tennessee around 9 miles. I've got up to 50+ mph on it with a 33cc 4 stroke engine. There comes a point the engine is no longer contributing and gravity takes over.

You are correct a really high gear ratio will do more harm than good if you don't have the horse power to pull it. A higher rpm doesn't mean higher horse power. These engines have a max rpm HP peaks at. Therefore it's a balancing act to get the reduction as low as possible and still maintain max HP rpm around full throttle that's what gives max speed.

I have a shift kit; so if I'm going way over max hp rpm it means I need to shift to a higher gear. If I can't get max torque rpm it means I need to shift to a lower gear.

With single ratio drive systems it then becomes dependent on throttle control and pedal assist. This is why I tell people a multi speed bicycle is better for pedal assisting than a single speed bicycle.

Therefore, more speed means you must have improved engine performance to produce more horse power. So the OP as of yet hasn't let the cat out of the bag as to how he's getting this alleged improved engine performance.
 

Greg58

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May 1, 2011
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Not me, the guys that have been here a while understand when someone new is trying to impress them with what they have done. I’m at the other end of that spectrum, I think it’s kinda impressive that two of my three bike engines are over 10 years old with one with a top end that is all original except the head.