Possible to build a homemade OHV 4 Stroke Bike?

[Waleed]

Hi, I'm new to this forum. I've built several motorized bikes and used different kits over the past two years. I thinking of going 4 stroke just because of maintenance and reliability. The thing is I'm also thinking of building it myself, with a 4 stroke OHV Lawnmower engine, from a good quality brand like honda, brigs etc.


The way these engines are made, makes it easy to convert. It seems like all you really need to do to convert is get a gearbox that fits the centrifugal clutch, a motor mount for the 4 stroke, wider pedals (If needed) and your good to go.


Any thoughts? I've only worked with 2 stroke engines on these things so far. I like that they are more simple, but dislike the problems that come with many of the engine kits factory quality.

 

[professor]

I have 2 bikes powered by 4 strokes.
You need to gear down the engine to the drive wheel.
Look in the 4 stroke section too.

I use a jackshaft between the engine and rear wheel (actually, I have a 3 speed bike hub as a jackshaft/ transmission after the primary jackshaft.

Another guy attaches a bike rim to his rear wheel and runs a belt right from the engine to it- like an old style motorcycle- search Lowracer here.
I do know that motorbicycles are not legal in Canada so be careful.

 

[Waleed]

Thanks, but actually I found a legal loophole around them here in ontario.

In Ontario a LSM is defined as:

"A limited-speed motorcycle is:

a motorcycle that:
can attain a rate of speed of more than 32 km/hr on level ground within a distance of 1.6 kilometres from a standing start;
has a maximum attainable speed of 70 km/h or less;
has steering handlebars that are completely constrained from rotating in relation to the axle of only one wheel in contact with the ground;
has a minimum seat height, when the vehicle is unladen, of 650 millimetres;
has a minimum wheel rim diameter of 250 millimetres and a minimum wheelbase of 1016 millimetres;
has a maximum engine displacement of 50 cubic centimetres or less; or,

if the motorcycle was manufactured on, or after, September 1, 1988, it must have affixed a compliance label required under the Federal Motor Vehicle Safety Act (Canada) that identifies the motor vehicle as a limited-speed motorcycle"


Moped:

"A motor-assisted bicycle is a bicycle that:

is fitted with pedals that are operable at all times to propel the bicycle;
weighs not more than 55 kilograms;
has no hand or foot operated clutch or gearbox driven by the motor and transferring power to the driven wheel;
has a piston displacement of not more that 50 cubic centimetres; and,
does not attain a speed greater than 50 km/hr on level ground within a distance of 2 km from a standing start."


Motorcycle:

"The Highway Traffic Act of Ontario, R.S.O. 1990, defines "motorcycle", as a self-propelled vehicle having a seat or saddle for the use of the driver and designed to travel on not more than three wheels in contact with the ground, and includes a motor scooter, but does not include a motor assisted bicycle ("motorcyclette")."




I personally have had no problems riding them around here. Most cops are pretty lieneant. I used to have a tomos scooter that I put away that was 49cc, and I put it away and stopped riding it. I rode it for about a month with an ebike plate lol, and got pulled over, and cited for no license, and improper plates. The first one was thrown away when I met the prosecutor and the last one, which isnt a moving violation, I had to pay for $110.


We have stricter laws here than most places about these things, but with motorized bikes, none of these classifications met having a bike kit engine on your bike.

Look at the moped and LSM classification, as well as motorcycle. The last one you can get away with by saying the bike has pedals and isnt self propelled. You have to pedal to start it.

 

[KCvale]

I thinking of going 4 stroke just because of maintenance and reliability. The thing is I'm also thinking of building it myself, with a 4 stroke OHV Lawnmower engine, from a good quality brand like honda, brigs etc.

The Professor and I have a lot in common, we know the joy of a 4-stroke shifter and like him I like a simple 3-speed hub.

Direct drive 4-strokers are fine though, they just need a little pedal help to get going.

Plenty of people like Harbor Freight 99cc Predators and fashion a way to mount them but I don't dink with that stuff, I just buy what I know works well and I like the midmount 49cc HS 4-stroke with the 4G belt transfer case.
The HS is pretty much a direct part for part knock off of the 50cc Honda and just keeps running.
I get them from gasbike which is great for direct drive as it has the wider cranks and such in the kit but for a jackshaft build the SBP shift kit comes with all the DD kit parts you need except the gas tank and throttle so you can score just the HS engine, a tank, the taranny and a throttle and be good.

Hope that helps as 4-stroke is nice if you travel a lot and don't mind the extra weight.