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hey guys i was interested in making a motorcycle but i dont know how fast an 8 horse power engine will go. How do i determine how fast 8hp is, infact how do i determine how fast any amount of horse power is. I would like it in mph please.


well. I'm not really sure if it really helps, but my 1965 Honda S65 had around 8hp with a 4 speed trans and did ~50-55 mph at around 5500 rpm. given, that was with a 10 year old on it, but I've read that that is about what they did with adults too. I'm interested in a project like this too, was thinking a small briggs engine with a old enfield or triumph trans, or what ever I could find of of ebay cheap.

Horse power is not a measurement of speed, but one of power... (( your ability to maintain that speed )) Now what type of motor is it ?? Is it a small gas job or are you building an electric bike ((Yes there is an Ible on that to )) ?? Is there a gear box / reduction on it ?? How are you connecting it the wheels ?? ((chain drive belt drive and what are the pulley / sprocket sizes ?? )) Honestly with out more info it's really hard to say, I've seen a 5hp honda in a small cart do highway speeds, (( About 70 mph )) sure it took a bit to get up there but it did...

its a briggs and strattons engine all i want is like a little go kart engine to put on my motorcycle bike. Its just a fun job i want to do with my son, and so then i can ride it to enjoy it.

An 8 hp in a small go cart for younger kids is more then enough, and without good suspension it's more then enough for most grown ups as well, and it would be a great starting project for a kid, they can always mount a bigger engine later, once they learn all about that one, you might want to consider building the frame to take something a bit larger later so you don't have to do a whole bunch of mods when / if that time comes..... And keeping it smaller right now is also nice if they are helping to build it because they can help lift it and most of the small engines are fairly easy to work on, and if they get the cart stuck they should be able to get it unstuck most of the time .. (( if you mount a twin cylinder 20 hp, you'll be the one pulling it out every time it's stuck in the mud )) It's only fun the first few times ... (( but on dry pavement my friends little go cart with a 5 hp honda GX-200 will do the posted speed limit and then some ... (( About 70 mph )) but it's more fun on wet grass...going in circles and spinning out every where...and even the kids 8 to 15 area don't bother us when it's stuck, the parents just stand on the deck and bother them, and some times use the garden hose to cool them down after all there hard pushing <> gotta have some fun ))

An 8 horse engine geared properly will go fast. A lot of small motorcycles (over the years) have had power in that range. What will determine the speed though is top RPMs, and gearing.


9 years ago

I don't know really. Like Bwana said, it's power. To give you a reference though, my garage door runs at 1/2 horsepower.