• Scam Alert. Members are reminded to NOT send money to buy anything. Don't buy things remote and have it shipped - go get it yourself, pay in person, and take your equipment with you. Scammers have burned people on this forum. Urgency, secrecy, excuses, selling for friend, newish members, FUD, are RED FLAGS. A video conference call is not adequate assurance. Face to face interactions are required. Please report suspicions to the forum admins. Stay Safe - anyone can get scammed.
  • Several Regions have held meetups already, but others are being planned or are evaluating the interest. The Calgary Area Meetup is set for Saturday July 12th at 10am. The signup thread is here! Arbutus has also explored interest in a Fraser Valley meetup but it seems members either missed his thread or had other plans. Let him know if you are interested in a meetup later in the year by posting here! Slowpoke is trying to pull together an Ottawa area meetup later this summer. No date has been selected yet, so let him know if you are interested here! We are not aware of any other meetups being planned this year. If you are interested in doing something in your area, let everyone know and make it happen! Meetups are a great way to make new machining friends and get hands on help in your area. Don’t be shy, sign up and come, or plan your own meetup!

Racing mower build

phaxtris

(Ryan)
Premium Member
Premium Member
Should i be working on other things, yes, am i working on said other things, NO! Sometimes you just have to work on something silly and fun

There is a demo derby in Crossfield in 2 weeks, ive kind of had my eye on marketplace for a real cheap mower to run for the intermission mower race, found this old craftsman ii with a 12.5 Tecumseh for 100$. I doubt i will win, but it should be a fun project, and a fun day, its a tight timeline so for now its going to be a pretty limited build

First thing was to see if it even runs, the carb that came with it was totally pooched, the previous owner took it apart and likely gave up there, its absolutely not save able. Off to everyone's favorite 1 day shipping online retailer....i could not find a direct replacement, at least not in the timeline i wanted and not for what i wanted to pay. I went with the closest thing i could find, a newer style carb for a Tecumseh in that hp range, not a direct bolt on however....many expensive tools to the rescue!

the wiring was also questionable, i rigged it up to hot wire with 1 wire to to at least get it running

Here it is, in all its glory

IMG_20250805_170812596.jpgIMG_20250805_174742358.jpg

Mmmm crusty, full of corrosion and all sorts of fuel residues
IMG_20250806_200107479.jpg

Some picture of making the adapter plate, and it all welded on with the carb installed, i have an air filter coming in tomorrow, i will have to make a sweet super high performance cold air intake...pics to follow

IMG_20250806_160606309.jpgIMG_20250806_163445830.jpgIMG_20250806_181521378.jpgIMG_20250806_181525364.jpg

Start, die, start, die, on and on, what the heck, carb is pissing fuel, pull the bowl, clean up the needle and seat, put it back on, start die, start die, my new neighbor thinks its pretty cool so he is out there, and normally doesn't have a whole lot of good input, but he kept on me about checking the plug "but its literally brand new", eventually i give in, nothing to loose, and then.....what the heck? was it like that when i put it in, i never did really look at it, just popped it in....anyways, throw the old plug in, fires up and idles no problem, smokes a lot, but runs, likely oil burning off the exhaust, and im sure the rings are probably a little stuck, who knows when it ran last

IMG_20250806_193051448.jpg


"Hey ill take a video for you" ... ok, why not, you all get to look at my ulgy mugg



Next up, new front tires (should arrive tomorrow), wiring it up properly, including a tether kill switch, air intake, and pulley swap for those extra mph
 
i dont think any you go in allow nitrous, but i haven't seen any restriction on hp, likely easier to just get a big v twin

im just going to run the stock 12.5hp motor without a governor

i think the limiting factor is more of the lack of suspension and rough ground, many of the rules i have seen also require you to run a lawn mower style idler clutch/slipper setup, you can probably only put so much power through that setup before its slipping and blowing belts
 
@phaxtris

So many questions...

Can you "gently tap" your competition or will you be running the course by yourself for a best time?

I have a vision of a bunch of these tractors slamming into each other on the first turn, tipping over, and guys scrambling to get them set right again.
 
I had a racing buddy that was into that. Kenny would race anything with an engine. Very first time I went to the drag strip I needed a helmet and he lent me his green Bolen helmet. He built various race tractors some with V8s. My car at the time with the warmed over 289 probably 350HP was just barely lifting the drivers wheel when I launched it hard. I stated I wished I had enough power to get some air like the 10s cars. His suggestion lets try the 5.71:1? pumpkin from my race lawn tractor next week and see what happens. It worked, lots of air, problem was I was at 7500RPM way before the finish line. It was a cool experiment withe somewhat predictable results.
 
@phaxtris

So many questions...

Can you "gently tap" your competition or will you be running the course by yourself for a best time?

I have a vision of a bunch of these tractors slamming into each other on the first turn, tipping over, and guys scrambling to get them set right again.

The one im shooting for is no contact, so no bumper car action. i dont know if any of them really "allow" hitting

Its not a time trial, where's the fun in that? so you do run with other guys/girls at the same time

ill try to make an insta 360 mount for it and take a video of the action
 
i dont think any you go in allow nitrous, but i haven't seen any restriction on hp, likely easier to just get a big v twin

im just going to run the stock 12.5hp motor without a governor

i think the limiting factor is more of the lack of suspension and rough ground, many of the rules i have seen also require you to run a lawn mower style idler clutch/slipper setup, you can probably only put so much power through that setup before its slipping and blowing belts

Local fair did that one year and I thought about putting a mower in for fun, but got busy and couldn't do it. Watching them ride around out there convinced me that I'd rather watch from the stands anyway lol. My back hurt just watching.

Looks like fun though. Hopefully you can get some video of it.
 
been hammering away at this thing over the week and today, made its maiden run tonight.....it sure feels fast, i tried for a video with my cell phone, but that didnt work out

Wiring, just a push starter and a kill switch/tether, (tach not shown) I haven't wired in the charging system yet, that's not a top priority, it runs off a mag, only need the battery for starting
IMG_20250808_221521445.jpg

The custom built gas pedal, this turned out functionally perfect, and doesnt look to bad IMO
IMG_20250808_221125483.jpg

Throttle linkages, return spring (some changes needed), fancy performance air filter because why not
IMG_20250809_211826895.jpg

The pulley swap, 6inch drive to 4 driven, from 5? drive to 8? driven. This project ate up an entire day, i figured on some unknowns, but this ate up a lot
IMG_20250809_121939640.jpg

Here was the big problem, the clutch as it came contacts the new drive wheel 🙁 what i ended up doing was move the clutch pulley and factory idler pulley rearward 6.25 inches (there was a convenient hole at 6.25 inches), this brought up another problem, the belt now contacts the post for the clutch wheel 🙁 off to princess auto for a ilder pulley, 50$! forget that, fabbed up one with a random bearing and some pipe, also made an adjustable mount for the extra idler pulley. This all sucked, but it did allow me to use the factory belt

IMG_20250809_132602529.jpgIMG_20250809_203257112.jpgIMG_20250809_204223129.jpg

I still have to make up some belt guides so that they dont jump the pulleys when the clutch is in, make a battery tie down, adjust the throttle return springs, and remove some slop out of the steering.

im sure other things will crop up, but that should get me going for next weekend.

im probably 400$ with purchase into this, the tires and battery ran up the bill by 180$, more than i wanted to be into it, but what can you do
 
Can you run dual rear tires to get more stability on corner drifting?
Me and friends converted a lawnmower to a 250cc motocross engine and trans. The 12 year old kid's lawn mowing business died once he could wheely for half a block. we had to put a castor wheel out the back of it...and the noise was brutal.
 
Pucker factor will probably be more of a hinderance than hp 😀 no suspension, dirt track, and high cg, i doubt i will even use the full 12.5 claimed hp 😀
 
I have a short list of things I want to experience yet - dirt track racing, driven by a few in the USA and it's insane how short and banked the courses are

Rattlesnake rodeo

Chili cook off

Southern cookout/pot luck

Dirt track you'll have less traction but with your HP you won't overpower the drives? Steering is the challenge on dirt track? I can see the first lap or two being cautious 😀

Video please
 
Back
Top