Engine size

[raceryan]

What is the biggest engines and horsepower that some of you all have attached to your bikes. I was looking at some small engines online, and began to wonder... There are so many engine choices out there.

 

[graucho]

Your going to hear a lot of varied comments on this. On a bicycle, mine was a liflan 150cc 4 speed. (approx 5hp) I chickened out at 50mph in 3rd gear. Remember bigger isnt better on a piece of machinery designed to go 20-40 mph max.
Pick an engine thats easy to get parts, and you can work on it yourself. Have fun.

 

[JemmaUK]

What is the biggest engines and horsepower that some of you all have attached to your bikes. I was looking at some small engines online, and began to wonder... There are so many engine choices out there.

Theoretically the sky is the limit - I have seen 50-60cc model V8s that would fit a modified bike frame and put out 6 and a bit horsepower at the crank...

Then again you could get a tuned single cylinder engine of around 40cc that puts out between 4 & 6 horsepower.

We havent even discussed 2-stroke vs 4-stroke yet - and then there are the semi-diesels...

The balance is basically durability and reliability against power and sensitivity. The more tuned the engine the less reliable it will be compared to the base engine.

The largest engine I have had is the 32cc tanaka - and to be honest if I was going to upgrade I would be more likely to go the tuning and fettling route than the cost of building something completely new..

Jemma xx

 

[kerf]

I'm running a 46cc @ a little over 4 hp. It's high reving giving a top end over 40 but I just run between 25 and 30. Save the motor and some of my old hide as well.

 

[weez]

My homebuilt recumbent has a Honda G100, 97cc 4-stroke sidevalve, rated 2.5hp @3600rpm. Will run 55-60km/h (35-40mph) on the flat.



I've had it up to 74km/h (46mph) on a slight downhill grade.

I'd never consider going such speeds on a typical upright bike. The steering head angle on an upright (particularly MTBs) is steep so the steering response is rapid for slow speed manoevering. The rapid steering response is a bad thing at twice the design speed- can contribute to speed wobblies.

My bike has V-brakes, which as rim caliper brakes go, are pretty good. They'd stop my bike from 55-60km/h all day long, but when I was riding it every day, it would eat a set of pads every 2 weeks and require frequent brake cable adjustment to compensate for wear. Rim heating after stopping from high speed was pretty scary. Ran my front tyre at about 85% max pressure, just in case, as it did most of my braking.