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Modgrain’s Motorized Bike

by: modgrain

Gravity Bike Dutch Bikes Direct

Zoom Bicycles Limited Edition ZB 80cc Black Slant Engine Kit

This might be a little off topic, but I have embarked upon a new project that has nothing to do with furniture design or woodworking. I’m building a motorized bike! Let me back up… I have been bike commuting for years now over 8 miles each way, however, due to a lower back injury I have been taking it easy and have found myself behind the wheel for just about every day this summer.

My “car” time got me thinking and wondering why are there not many little homemade mopeds or motorized bikes driving around? I’ve seen a few, but not many…. Is it price? Is it too complicated to build one? Is a 150mpg’s not enough? Or, maybe it’s the noise, and the fact that these little engines pollute the air too much? I’m not sure… I’m thinking these little gems will eventually be very popular in many cities. Especially if people realize how easy and inexpensive it is to get/build one. Electric bikes are becoming popular and people might feel that another gas engine is not good for the environment…. I guess that I’m in the camp of, if I can go 150 miles on a gallon of gas, this is a good thing (especially considering most cars only gets around 15 mpgs.)

I spent a few days researching engine distributors… such as:
Gas Bike
Kings Motorbikes
Daemon Bikes
Zoom Bicycles

They are essentially the same kits, but one stuck out. Zoom Bicycles provided a better online experience that was just more believable for me. Plus, I reached out to Gas Bike via a little “Live Chat (offline)” button and never heard anything back. (BTW, live “offline” chat buttons have to be the most annoying feature ever on a website.) Daemon Bikes kits are less expensive (I paid $129 no tax/shipping) and claim to have a superior chain and bearings as well as a handful of other parts.

Anyway there were 2 kits that made the most sense to me… The Black Slant 80cc or the standard 49cc (street legal) kit. From what I can tell the motors look identical. Where I live is very hilly, so I chose the larger engine. There’s a carb upgrade that claims to make the engine idle more quietly and give you a little smoother ride, but I held out for that option. Maybe it’ll be a future upgrade. One other thing to note is that the “slant” is a newer model where the spark plug is on a angle compensating for the angle that the engine is mounted and supposedly performs better than the standard kits. Below are the o/a specs.

This 80CC Slant Head Bike engine has 2.75 to 2.9 HP which is very powerful for an 80CC motor engine of that size. The kit comes with everything you will need to get started. Just add oil and gas. The 2 Stroke engine can reach speeds upwards of 40 MPH and has enough power to move even a larger individual. These engines have excellent fuel economy and gets about 150 miles per gallon of gas. Turn any mountain bike into a moped with this engine kit.
Engine Box #1

* 1 x 80cc Black Slant Limited Edition Bicycle Engine (Model: ZB-80S-BK)
* 1 x Dished 44 Tooth sprocket with 9 holes
* 1 x Thottle Assembly with built in Kill Switch and Matching Grip
* 1 x 48 inch Thottle Cable with tension adjuster
* 1 x 56 inch Clutch Cable with Heat Protection Spring, Separator Spring, and Clutch Cable Keeper
* 1 x Glossy Black Heavy Duty Push Clutch Lever
* 1 x 53 inch Heavy Duty 415 Chain

Gas Tank Box #2

* 1 x 1.8L (1/2 Gallon) Glossy Black Finish Gas Tank
* 1 x Spring Loaded Gas Tank Cap

Accessories Box #3

* 9 x Sets of Mounting Bolts, Washers and Nylock Locking Nuts for the Sprocket Assembly
* 2 x Rubber Sprocket Mounts
* 3 x Semi-circle Metal Sprocket Mounts
* 4 x Nylock Gas Tank Mounting Nuts
* 1 x High Quality Fuel Grade Line
* 1 x Inline Soft Plastic Fuel Filter
* 1 x Gas Fuel Valve with Nylon Fuel Filter and Fibre Washer
* 1 x Spark Plug
* 1 x Spark Plug Removal Tool
* 1 x Black Chain Guard
* 1 x Chain Guard Fasteners
* 2 x Fuel Tank Fasteners
* 1 x EPA Approved Exhaust Muffler with built in Catalytic Converter
* 1 x Heavy Duty Exhaust Muffler Clamp with Nyloc Nuts
* 1 x Adjustable Bearing Chain Tensioner
* 1 x CDI (Capacitor Discharge Ignition) Module with mounting assembly
* 1 x Large Frame Tube Adapter mounting plate with U Bolt and Engine Adapter Bolts.
* 1 x Parts Pack (2 x Exhaust Gaskets, 1 x Master Link and Keeper, 1 x Rear Engine Mount, 1 x Rear Engine Mount Clamp, 1 x Spark Plug)

Bicycle Requirements:
This 80cc Slant Head Bicycle Engine Kit fits most Men’s 24″ and larger bicycles which includes mountain, cruiser, the bike must have a V-frame with at least a 8.5″ height clearance for the engine. Larger frame size might require drilling of the bike. Ride you bike just like a moped

This 80cc Slant Head Zoom Bicycles Kit is about 8.5″ height 7″ length 5″ width and fits on most standard 24″ – 26″ or 25mm 29mm frame bicycle frame tubes.. This engine kit only adds about 22 lbs to your bike.
Gas And Oil Mixture For Fuel Ratio: Use of a good synthetic 2 stroke oil is recommended.
This bicycle moped 80CC slant head motor engine kit is a 2 cycle/2 stroke design, therefore, a gasoline/oil mixture is necessary as follows:
• When New: 16 to 1 (8oz per Gallon)
• After 3 Tanks Of Break In: 32 to 1 (4oz per Gallon)
The engine crankshaft bearings are lubricated from the oil in the gas mix. A rich break in oil mixture ensures bearings will not cease during engine break in period.

Now moving on to my decision about what bike to put this motor on… after hum hawing about picking up a used bike on Craigslist, I decided to look at a new bike from BikesDirect. I previously bought my road bike there a few years back and thought it was a great deal! You can see the picture above, but the specs are here. I’m not a big hybrid know it all, but this bike looks to be a decent bike especially for the low price of $269 (no shipping, no tax), plus it has fenders and a kick stand! Here are the details about the bike:

Frame  Lightweight Welded Aluminum with multi-shaped tubes and reinforcing gusset. Replaceable rear derailleur hanger, 2x H2O brazeons, Fender mounts and Fenders (included)
(Fenders are Grey or Black)

Fork Zoom/Enjoy Aluminum Suspension Comfort Front Shock
Stem Adjustable Height/Angle, Aluminum alloy
Derailleurs Shimano Tourney SIS Index, SR Suntour
Shifters/Cassette SRAM Gripshift MRX 21 Speed, Shimano 14-34T SIS Mega-Range Cassette
Brakes/Levers ProMax Linear pull ‘V’ type Aluminum
Hubs Formula Forged Aluminum Alloy with quick release and dust sealed ball bearings
Rims Aluminum 700c with 36 holes
Crank TH Forged SteelArm triple 48/38/28T
Saddle Comfort wide-style w/suspended Spring base Seatpost Comfort Suspension Seatpost, Aluminum alloy
Pedals Resin Dual-purpose
Tires Comfort-ride 700 x 35c
Colors Blue Nightshade or Gloss White
SizesMen’s – 15″, 17″, 19″,  21″, 23″

Both the bike and motor have shipped and should be here this week. More to come!


  1. April Kunz Said,

    September 19, 2010 @ 6:59 pm

    This is so awesome! Put it together as soon as you get it and post us some video! I think Paul would love one for his thirtieth bday.

  2. modgrain Said,

    September 30, 2010 @ 3:38 am

    Here’s my update. I got the bike and the kit. The kit is installed. However, I haven’t been successful to get the electronics working. There are a couple possible problems. The CDI or the Magneto. Zoom Bicycles has been very responsive to my request about sending both parts out (under warranty). They shipped today. So… more to come. Ill also post more details about the install… as there were several custom modifications to make it fit on this bike.

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