I would like to make a honda gx160 engine a bit more torquey. These engines are used on lawnmowers, portable generators and go-karts. So I'm just wondering if there are any general rules that you can follow to make a 4-stroke have more torque?

Cheers

Bigger carb? I've had a few 4 stroke dirt bikes, but there wasnt much between the power and torque, it was just a case of making it 'faster'.

Port and polish.

Slight Richening of mixture from stochiometric.

Compression and cam. You need more piston pressure to get more torque.

scrap it and fit a motor bike engine, them lawn mower engines are never gonna be fast. even some thing like a Honda CG125 engine fitted to a go-kart (i'm assuming thats what its in?) would be a shit load better than the normal engines you get in them.

I have to run 160's otherwise I can't race... and it's not that slow, will happily pop along at 60mph.

I was thinking about doing something to the cam, like pulling the lobes off and adjusting the difference between max lift of each lobe and the cam centreline. But I need a deflection gauge to do it....anyone know where I can get one?

What about lightening components like the flywheel and possible the crank? Will this affect the torque?

Edited 13 February, 200818 yr by jamesjuniorfizbob

if u racing are u allowed to mod the engine at all?

Reducing inertia in the components will not help the engine develop torque as this is all down to the push on the top of the piston, but it does help reduce the parasitic losses.

A/F approx 10% richer than stichio will give max torque.

Riskie, I'm only racing non msa events at the moment so although I have to race with 160's and on certain tyres etc. no engine checks are made. Don't worry I'm not the only one to do it. I jumped in someone else's kart on monday and I was 3.5secs quicker than I have ever been on my kart....no one can say that's not dodgy..

I take it stichio is just a fancy word for standard?

Make the flywheel heavier. You'll lose power, but gain torque.

Riskie, I'm only racing non msa events at the moment so although I have to race with 160's and on certain tyres etc. no engine checks are made. Don't worry I'm not the only one to do it. I jumped in someone else's kart on monday and I was 3.5secs quicker than I have ever been on my kart....no one can say that's not dodgy..

I take it stichio is just a fancy word for standard?

Stoichiometric is the name given to a theoretically perfect air/fuel mixture - about 14.7:1 air:fuel.

Make the flywheel heavier. You'll lose power, but gain torque.

Err, no you won't.

Err, no you won't.

Umm ok, explain why not!! Maybe the wording was incorrect. Probaby mixing torque with inertia.

Edited 15 February, 200818 yr by phatt-polo

By lightening the rotating mass you will lower the amount of energy lost, so in theory the car/engine will put more power (and torque!) down at the wheels.

You will not lose torque from fitting a lighter flywheel, or gain torque from fitting a heavier flywheel.

meh.. flywheels, probably best off leaving it alone.

hmmm. how to make an engine more torquey?

move south!!!!! :-D