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Iknow if we put oon some larger tires it will go faster, but thats only a few km/h, but i want it to go 40-50m/t.
Can i only change engine to a moped engine?
A lawn mower have from 8 to 20hp, but a moped only have 2-3hp? but a lot more RPM

Jonas94 said:

Iknow if we put oon some larger tires it will go faster, but thats only a few km/h, but i want it to go 40-50m/t.
Can i only change engine to a moped engine?
A lawn mower have from 8 to 20hp, but a moped only have 2-3hp? but a lot more RPM

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Jonas you don't want a lawn mower, you want a go cart.

no, i want a fast lown mower.
The reason is simple, who will stop a lown mower couse it drives to fast..?
And how fun would it be to drive from a moped ?

Someone have a idea what i can do?

If you're wanting to mow a lawn at 30 mph....forget it, it will never work. Your blade speed would have to be so high the blades and spindles would grenade. Besides, you won't have enough room to drive it at that speed, unless your yard is several acres in size and freeway smooth.

If you're wanting something to drive down the road and not get pulled over by the cops, you can forget that too. True, I don't know of anyone that has ever been stopped on a mower for not having a license plate or insurance on it, but I do know of someone that was arrested for DUI on one. Anything driven on the road has to comply with your local, state and federal laws. Even a bicyclist can be ticketed for speeding or running a stop sign.

The first thing would be is remove the governor. Then you would have to experiment with drive belts and pulleys. I don't know how fast you want to go but you might want better brakes also.

Fix the steering & brakes so they will function properly above 10 mph & insure that the front wheels will stay on.... then after you have it controllable you can address making it go faster...

Here is a fun youtube...Lawn Mower Racing Rockingham NWLMRA - YouTube

And here is a starting point... Lawn Mower Racing Secrets

Don't kill yourself right away, get some pictures & videos to post back here first... :smile:KennyV

reynoldston said:

The first thing would be is remove the governor. Then you would have to experiment with drive belts and pulleys. I don't know how fast you want to go but you might want better brakes also.

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What is the governor, read about it, but does it have with the RPM or gasoline intake..?

I would not recommend messing with the governor, it's purpose is to maintain speed and keep the internal rotating parts from exiting the side of the engine. One of the guys at work made a scary fast mower by just swapping the pulleys front to back. He also replaced the front axle with one that was a bit wider and lower for stability. It helped that we had a complete fab shop with all the goodies though.

Jonas94 said:

What is the governor, read about it, but does it have with the RPM or gasoline intake..?

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The governor keeps the throttle adjusted to have the engine run around 3200 RPM. At this RPM the mower engine runs the most efficient for operating lawn equipment. To eliminate it you would have to do away with the carburetor linkage and just hook it direct to the throttle plate. I have a friend that races go carts and the first thing they do is do away with the governor. It really shouldn't do any damage because they get two seasons out of a go cart engine. Also you don't run a governor on a car or motorcycle and you get long-life from them. Now you need a nice straight pipe without a muffler for a nice sound. Keep in touch as to how it turns out for you because it sounds like fun.

Get a combination hour meter/tachometer like the one Norther Tool sells. That way you can keep an eye on the rpm's with the governor removed. I know for a fact these engines can spin 5,500 rpm's with no damage.

reynoldston said:

It really shouldn't do any damage ....

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Here's a link to Old Mini Bike Forum that shows what happens when a flywheel grenades...

Removing governor on your engine and omb !!! Please read !!! - OldMiniBikes.com Forum

Keep the governer or upgrade the flywheel/rod. If you want to just go fast the suggestion of swapping pullys seems to be the best route.

If you don't know what a governor is I don't think its a good idea to make a racing mower. Not trying to put down your dreams but ask someone to do it for you so it will work :biggrin:

motorrefurb said:

If you don't know what a governor is I don't think its a good idea to make a racing mower. Not trying to put down your dreams but ask someone to do it for you so it will work :biggrin:

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Once Jonas94 has removed the governor, he might as well remove the mower deck. The reason is that after this is done all the mower would be good for is going fast or a salvage yard. So I guess what difference would it make. I am sure he knows he will be destroying his mower, his money and mower so I say go for it. I am seeing people all the time trying to repair there mower on this forum and not knowing what they are doing.

depending to the grass as well to the mow together with the effort of tractor

mullins87 said:

Get a combination hour meter/tachometer like the one Norther Tool sells. That way you can keep an eye on the rpm's with the governor removed. I know for a fact these engines can spin 5,500 rpm's with no damage.

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Having no governor will make it difficult cutting too, the engine will bog in thick grass unless you open it up, and race at mega revs in thin grass unless you back off throttle, and your centre of gravity would cause an instant flip over if you try turning at high speed. You'd need independent front suspension, roll bar, harness, a helmet and life insurance.

one ofthe rules of the lawn mower races is that the blade is removed for safety precuations. if it flips, you do not want the blades to engage and chew the body to pieces. the best way to improve on the speed is to use larger pulleys to drive smaller pulleys, thus increasing the speed. of course you may have to rrebuild the drive axle and installl heaveir gears and seals

I'm new here, but a governor does many things, including keeping the engine at a SAFE operating speed. Removing the governor is fine, IF, you replace the stock flywheel with a steel billet, replace or rework the crank, etc. When that stock flywheel comes apart, and it will sooner or later, the damage it will do is remarkable. You might think losing a leg or life is fun, but the innocent bystander might have a different opinion.

As for the above comment about safety at 5,500 rpm, be cautious, I've seen pictures of flywheels that came apart well below that speed. 4,000 rpm would be a much more reasonable number unless you're made the appropriate modifications.

Dale, likes to go fast, but also likes to stay in one piece.

thirdroc17 said:

I'm new here, but a governor does many things, including keeping the engine at a SAFE operating speed. Removing the governor is fine, IF, you replace the stock flywheel with a steel billet, replace or rework the crank, etc. When that stock flywheel comes apart, and it will sooner or later, the damage it will do is remarkable. You might think losing a leg or life is fun, but the innocent bystander might have a different opinion.

As for the above comment about safety at 5,500 rpm, be cautious, I've seen pictures of flywheels that came apart well below that speed. 4,000 rpm would be a much more reasonable number unless you're made the appropriate modifications.

Dale, likes to go fast, but also likes to stay in one piece.

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My grandson ran a go-cart with just a stock lawn mower engine and no governor for years till the connecting rod broke but never had flywheel or crank problems. My son-in-law replaced the rod and grandson ran it till he had out grown the go cart. Still runs. Of course I have no idea how many RPM it ran other then it made a lot of noise seeing it ran a pipe and no muffler.

reynoldston said:

My grandson ran a go-cart with just a stock lawn mower engine and no governor for years till the connecting rod broke but never had flywheel or crank problems. My son-in-law replaced the rod and grandson ran it till he had out grown the go cart. Still runs. Of course I have no idea how many RPM it ran other then it made a lot of noise seeing it ran a pipe and no muffler.

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If you're happy putting your grandson at risk, that's your choice. I'm not here to argue, just saying more than one person has lost a limb, or worse, running an engine without a governor that was designed to have one on it.

Dale

Most of the dirt tracks around here run go carts on Sundays and in the 20 years I have been going I have never saw a fly wheel come apart. Now I have broke fly wheel bolts in my car

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Cast iron, small engine, flywheel. This is why billet flywheels are available.

Your choice. It does happen. I could never with a clear conscious recommend someone to do something that has a possibility of such catastrophic results when there is no need to take the risks.

If this persons removes the governor, then looses a leg, my conscious is clear. Denying that it can happen because you haven't personally seen it does not mean it doesn't happen.

Sorry I'm off to such a rocky start here, but I just can't set back when it comes to recommending such dangerous activity to others.

thirdroc17 said:

If you're happy putting your grandson at risk, that's your choice. I'm not here to argue, just saying more than one person has lost a limb, or worse, running an engine without a governor that was designed to have one on it.

Dale

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Not to put my grandson at risk, because for one thing I have no say. Also not here to argue. Just what experience I have seen. I also have a customer that races go-carts and they have a stock class and I am not sure on this but I think all they do is remove the governor. This also I would have no say on. As far as myself everything I own has a governor and set to specs. I have never seen a small engine flywheel explode but just because I have never seen it doesn't mean it can't happen it just means I never seen it. What I have seen happen being a truck mechanic and more then once is truck clutches that this has happen to and what damage it can do along with race cars. No I wouldn't want my feet or legs near the bell housings.

In the class I race we run a ford 2.3 with a ten thousand rpm clutch and we half to put a 1/4 inch plate on the floor. At 300 hp and ten thousand RPMs you don't want anything to come up to you

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thirdroc17 said:

Sorry I'm off to such a rocky start here, but .....

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Hello Dale & WELCOME to LMF...

Not a rocky start... most here don't get easily offended by comments, And it is good to consider safety now and then... :smile:KennyV

Thanks, Kenny.

Now, back to tightening up the steering, improving the brakes, and swapping those pulley's so we can go fast on a lawn mower! Yup, been there, done that. It's a good idea to lower them too, the lower center of gravity makes for a more stable ride.

thirdroc17 said:

Thanks, Kenny.

Now, back to tightening up the steering, improving the brakes, and swapping those pulley's so we can go fast on a lawn mower! Yup, been there, done that. It's a good idea to lower them too, the lower center of gravity makes for a more stable ride.

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Just curious how do you swap pulleys? wouldn't the pulley shafts be completely different? I have heard this on this forum elsewhere but never heard how it is done?? Most of the riders I have worked on have a double pulley with a large shaft bolted on to the engine and the driven just a small splinted shaft. I don't even know where you would buy something like this to fit? Would you have something custom made at a machine shop?

By swapping pulleys, I don't mean swapping the two that's there. Swap out either or both the stock pulleys for different ones. Pulleys can be bought at a variety of places, one is https://phoenix-mfg.com/ Just be sure to NOT get a fractional horsepower pulley.

The rear pulley is typically larger, and a single pulley. Get one of the same shaft diameter and belt width. Half the diameter will result in twice the speed. That may not sound like much, but unless you upgrade the steering, might be enough. Depends on how tight your current setup is.

Remember, this may require a change of drive belt too. A smaller rear pulley would mean a shorter belt. It might very well require a modification of the tightening system, typically it's just an idler pulley connected to the clutch pedal. Depending on the idler/tightening set up, you might be able to modify it enough to take up enough slack to get away with the stock belt.

Every mower is different. Each has to be modified in it's own way.

Good luck, and happy motoring.

Dale

No thank-you I won't be changing any pulleys on my equipment unless its stock. I was just wondering about this pulley swapping which didn't make a lick of sense. More like pulley changing. Thanks for letting me know about the Phoenix company because next time I need a pulley I will check there.

thirdroc17 said:

Sorry I'm off to such a rocky start here, but I just can't set back when it comes to recommending such dangerous activity to others.

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No rocky start here either, most if not all of us are thicker skinned than that. Your pictures made me think of a neighbor about 20 years ago that was having trouble starting his Snapper RER. It was an early 80's model Hi-Vac with a B&S 12 hp engine. He had been cranking on it relentlessly for probably 5 minutes when we heard a loud BOOM!!! My dad and I were in the garage, which turned out to be a good thing as immediately after the boom we heard shrapnel showering the side of the garage. Some of it was embedded in the siding. I finished the summer mowing his yard for him, but nearly everytime I did, I would find another piece of his engine. :laughing:

Yeah, it does happen. I won't say I've never done anything unsafe, I just draw the line at any kind of recommendation that might harm others. I mean, if you can sue McDonald's for selling hot coffee that's hot, I can see people hurting themselves, then coming back to a forum and pointing fingers.

If anyone wants to take the risk, it's their risk, not my comments that got them hurt.

I found the cheapest way to go fast is to drive up a huge hill turn around and put her in neutral and hold on!!!!! And no sudden turns. I got pulled over for going 43 mph. Then the cop tried to get me for a unregistered off road vehicle... Moral of the story. Just find a way and go for it!!!!

Well I'm also building a racing mower. But I do not have any big hills any where around me.

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The simplest way to make one "quicker" is to reverse the pulleys underneath the mower. Put the one on the rear on the engine.


I know back in the day folks removed the mufflers and replaced it with a pc of pipe that had a flat washer welded over the end, I have no idea if that helped anything or not.

hitmanharleyk said:

The simplest way to make one "quicker" is to reverse the pulleys underneath the mower. Put the one on the rear on the engine.

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I don't think so seeing they would be completely different design?

I was playing with mine today put a foot Pedel on it to control speed. And added two extra pulleys on the drive belt so there is not so much belt flop. I kept my front pulley the same just cut the bottom pulley off that would run the deck belt and put it on the back this thing is crazy fast. And yes I did work on the front end it does fine in the dirt but in the road it wonders all over the road need to find a way to fix that

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Carscw said:

I was playing with mine today put a foot Pedel on it to control speed. And added two extra pulleys on the drive belt so there is not so much belt flop. I kept my front pulley the same just cut the bottom pulley off that would run the deck belt and put it on the back this thing is crazy fast. And yes I did work on the front end it does fine in the dirt but in the road it wonders all over the road need to find a way to fix that

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Bushings are probably worn out on the steering post if that is loose. They may be worn out on the axle.

reynoldston said:

I don't think so seeing they would be completely different design?

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If they're keyed the same with the size, or weld them on. Stock the small pulley is on the engine and the big one is for the transmission. This gears it down, as the smaller one will spin fast but the larger one spins at a slower rate. When the large one is on the engine it'll spin just as fast, but now its turning the smaller one at a faster rate.

All my bushings are new the front tires are not made for 30 mh speed I took the bottom pulley that would run the deck belt and drilled the hole to the rear end shaft side then cut a grove for the key. If you go to big on the front pulley you lose to much take off speed. I can carry the front wheel 2 feet off the ground for close to 30 feet

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Single rotor? Won't be much good for mowing but great for getting you kicked out of your neighborhood lol. Here's a vid. http://www.youtube.com/watch?v=nOjk9RCzg9Y&feature=youtube_gdata_player

That is insane I have a ford 2.3 engine Going out to the shop now to draw up some plans to build one

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Your putting a 4cyl on your mower? It was nice knowin ya lol

I have a ford 9 inch rear end that I had made to make a go kart for drag racing. I will build a tube frame and put a craftsman body on it then let my dumb brother inlaw test drive it. Won't really be a mower but will look like one. This might be faster than my go kart with the Honda 750 on it

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Hey, this is what you need to do

How to: Lock a Trans-axle or Differential Video

How to: Lock a Trans-axle or Differential - YouTube

mullins87 said:

My dad and I were in the garage, which turned out to be a good thing as immediately after the boom we heard shrapnel showering the side of the garage.

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And what happen to your neighbour?

I built a racing mower a few years ago.
To go fast all it takes is about 15 minutes and a smaller pulley with appropriate shaft diameter on the transaxle.
You can get them off the shelf at Tractor Supply Store.

I couldn't say not to do it enough though.
It will be fun for about 10 minutes,then you will realize that not being able to stop at such speeds scares the hell out of you-and I was on flat pavement.

Mower's have NO brakes,the small disc on them is to slow and stop it for shift/gear change and that's it-they aren't made to stop a mower at even top speed stock.

After about 5ft you will have zero control,because the front end is too loose.
Even brand new,they are loose because they are designed for low speed.

One thing that is cool and horrible at the same time is you will almost instantly be near top speed when you take off,there is almost no lag between stopped and ludicrous speed.

IF I were to do it again,I would do the brakes FIRST-Then the suspension/steering THEN start dropping pully size's.
You don't need to alter the governor at all,hp isn't what is making it slow. It's a function of gearing,which is easily overcome with a pully swap and smaller tires.
By the time you NEED more hp,or raise RPM for higher top speed then you'll understand plenty about racing mowers.
For now,leave it alone and fix the gearing issue with the pulley's.

It only took an 8hp tecumseh about 5m to make me realize power isn't the issue,it's keeping it to the ground.
I couldn't imagine a pulley swap on my 26hp mower,it has left black marks on my concrete just taking off in 6th!
And that was factory stock and 24hp before motor swap.

Def-Ed said:

..... and smaller tires.

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You sure about that?

To lower the mowers center of gravity for a somewhat more stable ride, yes.

Depends what your after really.
Shorter=quicker,taller=faster
Shorter tires will effectively raise the overall ratio,allowing for quicker acceleration.
Taller will lower ratio which would give you a higher top speed.

I say smaller mainly because taller will raise your already bad center of gravity.
Assuming brakes/steering were modified,my personal preference would be towards smaller for that reason and I would raise RPM or pulley ratio to attain desired top speed.

Top speed is simply a function of RPM and gear ratio,I was trying to lean him towards safety/acceleration versus top speed to keep him from killing himself.
Admittingly though,acceleration isn't much of an issue on these little things once modded
You caught me

Best thing is have front and back pulleys the same size my craftsman is a five speed in third I can play in the mud Fo burn outs wheelies for over 20 feet. In 5th I can still carry the front wheels over 20 feet and top speed is 43 mph. Engine is a very old 14.5 off a old snapper was going to put a Briggs 20hp twin but don't really need or want twice the RPMs.
No brakes at all never had a need for them.
I used a bike brake lever and cable as a gas Pedel
Welded the front end and run go kart wheels with bearings. Only big problem is a belt only last about four hours but saw I clip on how to make a clutch

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please invest in a yard sale motorcycle helmet:confused2: oh, and stay thirsty my friend :licking:

yes these engines will run 5500 rpm but they won't do it at a constant speed like mowing a years i use to race go karts and we took out the governors also but they were never at a constant speed the throttle was wide open then closed then wide open then closed it works for racing but not sure it will work for mowing

Could you use a go kart or ATV clutch?

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Police here in my town pulled over a guy on a mower and arrested him for DUI...
They can and will stop you and ticket you for having an unlicensed and/or unregistered vehicle...there is ALWAYS something they can stop you for...

but above all, I would not do it because it just would NOT BE SAFE to do...brakes, wheels, tires, bearings, frame...NOTHING on that mower is designed or engineered for the stresses that those speeds would put on the frame and drivetrain. You would end up hurting yourself...or worse yet, some innocent family driving down the road!

heymow.com is my favorite site for turning lawnmower money into noise. I'm getting old, but I have no desire to take something that is designed for 6 mph, and make it do 40 without the proper modifications. I've personally seen a stock flywheel blow apart at 4600RPM (fortunately in a controlled environment) and the damage it did. As several others have rightfully noted, steering, brakes, tires, suspension, and a slew of other less readily apparent mods are needed to safely and routinely take these machines to even stock go-kart speeds. A $4,000.00 investment isn't unusual in one of these. One can only dip into the good luck well so many times before it comes up dry, and that is a bad place to be.