Lawnmower (small engine) performance?

[iwannadie]

Just curious if anyone has done any mods to their lawn and garden type of equipment? :clap:

I recently tore my 32cc weed wacker down for a good cleaning and basic maintenance and thought it may be fun(and good learning experience) to start playing with these things. I've seen a few people talking about better exhausts and bigger carbs etc.

 

[WB9YZU]

You didn't mention whether it was 2 or 4 cycle, but I guess it doesn't matter much.

Power tools are generally designed to be reasonably quiet and reliable. Thus, there are modest power gains to be made in the system.

Different porting, larger carb, more open exhaust. Remember, this is a system, and each change you make, makes a change somewhere else, and there is no computer to compensate for the change.
For example: Larger ports may improve top end efficiency, but you may lose on the bottom end of the RPM spectrum. A more open exhaust may leave the engine on the lean side. A larger carburetor without improvements in other areas may make the engine unresponsive to throttle changes. There are racing classes for lawnmowers, go carts, Jr Dragsters that are based on reasonably small engines (130 cc or so and smaller). You'd be surprised for example to see someone get 25hp out of a 5hp Briggs, but reliability is way down, and maintenence is way up.

I like my power tools reliable. They have to start easily and do they job they were designed for. That's how I measure power tool performance

 

[GrimmJeeper]

in tech school me and a buddy tore down a tecumseh 5hp engine and bored it out to take a piston from a 1.5l honda, put a crafstman crank in it from a bigger engine and a carb from a riding mower on it. i don't know how much power it puts out but it was a beast in the gocart we built around it. it's still sitting in the corner of my garage 20 years later you make me want to dig it out and build another frame to bolt it to...

 

[iwannadie]

You didn't mention whether it was 2 or 4 cycle, but I guess it doesn't matter much.

Power tools are generally designed to be reasonably quiet and reliable. Thus, there are modest power gains to be made in the system.

Different porting, larger carb, more open exhaust. Remember, this is a system, and each change you make, makes a change somewhere else, and there is no computer to compensate for the change.
For example: Larger ports may improve top end efficiency, but you may lose on the bottom end of the RPM spectrum. A more open exhaust may leave the engine on the lean side. A larger carburetor without improvements in other areas may make the engine unresponsive to throttle changes. There are racing classes for lawnmowers, go carts, Jr Dragsters that are based on reasonably small engines (130 cc or so and smaller). You'd be surprised for example to see someone get 25hp out of a 5hp Briggs, but reliability is way down, and maintenence is way up.

I like my power tools reliable. They have to start easily and do they job they were designed for. That's how I measure power tool performance

I get you on wanting things reliable, I get made fun of for doing maintenance on my lawn equipment but I am like you, I want it reliable. As for messing with things in a performance way it would be for fun and for Toys not really my main stuff. I like that my weed wacker cranks first pull, I don't want to go down the road with my main gear. I thought about picking up some used stuff and just seeing what can be done with it. When the project stuff breaks, I will just bust out the reliables...

 

[seanR]

A lot of times if all you want is more speed you can regear it using different belt pulleys, lawn mower engines are pretty over powered if you just want to go faster and not mow with it.
We took one that is owned by a famous musician friend and we got it to go almost 40 MPH just by changing the pulleys.

https://www.youtube.com/watch?v=36zMWISW8hw

 

[cal]

who would build a racing lawnmower?!

 

[David_Bricker]

who would build a racing lawnmower?!

Uhhh, pot, meet.....

David Bricker / SYR

 

[cal]

Sick bastards

 

[StinkyArmpits]

I'm in the middle of go kart builds for the kids and I. I'm using harbor freight predator 6.5 HP engines. You can buy a ton of go fast parts cheap. Cams,timing keyways, intake,exhaust on and on. They are a ton of fun!!!

 

[GSequoia]

in tech school me and a buddy tore down a tecumseh 5hp engine and bored it out to take a piston from a 1.5l honda, put a crafstman crank in it from a bigger engine and a carb from a riding mower on it. i don't know how much power it puts out but it was a beast in the gocart we built around it. it's still sitting in the corner of my garage 20 years later you make me want to dig it out and build another frame to bolt it to...

Do they make bypass shocks in the 6" travel range?

 

[cal]

Do they make bypass shocks in the 6" travel range?

http://www.offroadshocks.com/product/King-Bypass-Shocks-25/PR2506-BP3.html

triple bypass 6" shock.

 

[Overland]

A friend of mine built a Craftsman with a CB650 Honda SOHC4 engine. It goes faster than you want to go on it, but he built it for lawn tractor pulls.