"The Mowercycle" a microcar road legal trike

I'm back to working on this. My ADHD makes me cycle through hobbies every few months. It's super annoying, but at least I am managing to spend longer on one hobby as I get older.

I pulled the mowercycle out of the shed. It was covered in spiderwebs and a little more rusty but still pretty much the same. I have an old motor-generator that I took apart and cleaned and now it works, so I put that on instead of the gas tank. I'll be relocating it somewhere else and using a vacuum powered fuel pump.

I also tried to flip the engine around. However, it doesn't fit well that way. For now I just left it off, and I'm going to weld up the front axle while I have better access to that area. I'm pretty sure this engine isn't the original. It sits on a steel plate, and it was bolted through the plate to the frame on one side, but it was just bolted to the plate on the other side. The plate wasn't welded to the frame or anything either. So it was only two bolts holding the engine to the frame. The information plate is long gone, but I bet this is probably like a 10 horsepower engine. It seems a bit bigger than the 8hp one I have in the barn.

So there's a bit of a problem. This engine is way too big and old. It needs a battery to power the coil, and it's size just doesn't match the shape of the rest of the vehicle. It's also going to be hard to route the jack shaft v belts around it with it flipped around. I'm thinking about trying to trade it for a new predator 212 or something similar. It's in pretty good shape. There's some leaky seals, but I managed to get it started this weekend without too much trouble. I'll think about it.

I know the feeling, I don't have ADHD but Asperger's and jump around on projects all the time.

At least at my age I have learned not to do total tear downs anymore, keep it driving and useable as much a possible so it stays interesting.
I still have a total tear down project from 3 years ago that I might finish in the next 20 years

Love the project though.

rolphill wrote:

I'm back to working on this. My ADHD makes me cycle through hobbies every few months. It's super annoying, but at least I am managing to spend longer on one hobby as I get older.

I pulled the mowercycle out of the shed. It was covered in spiderwebs and a little more rusty but still pretty much the same. I have an old motor-generator that I took apart and cleaned and now it works, so I put that on instead of the gas tank. I'll be relocating it somewhere else and using a vacuum powered fuel pump.

I also tried to flip the engine around. However, it doesn't fit well that way. For now I just left it off, and I'm going to weld up the front axle while I have better access to that area. I'm pretty sure this engine isn't the original. It sits on a steel plate, and it was bolted through the plate to the frame on one side, but it was just bolted to the plate on the other side. The plate wasn't welded to the frame or anything either. So it was only two bolts holding the engine to the frame. The information plate is long gone, but I bet this is probably like a 10 horsepower engine. It seems a bit bigger than the 8hp one I have in the barn.

So there's a bit of a problem. This engine is way too big and old. It needs a battery to power the coil, and it's size just doesn't match the shape of the rest of the vehicle. It's also going to be hard to route the jack shaft v belts around it with it flipped around. I'm thinking about trying to trade it for a new predator 212 or something similar. It's in pretty good shape. There's some leaky seals, but I managed to get it started this weekend without too much trouble. I'll think about it.

fbisurveilancevan wrote:

I know the feeling, I don't have ADHD but Asperger's and jump around on projects all the time.

At least at my age I have learned not to do total tear downs anymore, keep it driving and useable as much a possible so it stays interesting.
I still have a total tear down project from 3 years ago that I might finish in the next 20 years

Love the project though.

I know the feeling. Clinical OCD. Fun when I start a project and then second guess myself and undo everything or procrastinate everything out of fear of breaking something lol. I’m enjoying reading this thread.

I wonder if it might be advantageous to mount the motor closer to the rear tire, thus minimizing the weight on the steer axle. IDK, I’m not knowledgeable about things with less than 4 wheels.

Okay. After thinking about it, I've come to a decision. The easiest way to do this is going to be to just cut off the drivetrain on the right, and reweld it on the left. The main parts are the cvt bracket, the cvt lever, and the tensioner. The cvt lever bracket is bolted on, so that doesn't even need any welding. I'll have to cut off the cvt bracket, and reweld it on the other side. The tensioner isn't symmetric, but I should be able to modify it to work on the other side.





The only concern is the cvt lever. The steering wheel shaft is on the left side of the frame, right where the lever should go. I'll probably remount the lever where it fits and I can reach it easily, then cut the lever arm and weld on an addition to make it reach the cvt.

This seems like some work, but it's going to be less parts, less belts and clutter, and probably easier than trying to make a jackshaft and all that stuff.

After that, I have to remount the gas tank (I'm thinking behind the seat would look best), plumb up the vacuum fuel pump, then go for a terrifying brakeless test ride. After that I'll add a throttle and brake pedal to those two foot pegs. It's nice that the rear wheel already has a built in brake.

Oh yeah, I had an old motor-generator that I thought was junk. Well I cleaned it out and it works. So I installed it on the engine instead of the gas tank. No more rope starting! I got a little vacuum operated fuel pump to pump the gas from wherever I mount the tank now. For now I'll just use it to start the engine with jumper cables. Eventually though, I want to get a regulator and starter solenoid so I can recharge the onboard battery.

Big progress! The drivetrain is pretty much complete. Swapping all the stuff over to the left side was a good idea. It ended up being way simpler than trying to add a jackshaft and all that mess.  The rear pulley was just something that fit from a barn sale. It's a cheap zamac pulley, but it will work for a test until I get a heavier duty one installed. I ended up not using the original cvt lever, because it was really not designed to be in any position other than where it was.  I think I spent about 5 hours total this weekend on the bike.




I used the lever I was originally going to use for the clutch that didn't end up being feasible. I decided to just use the cvt as a belt clutch. That seemed to work well enough back when the tractor was still a tractor. Plus I have a couple spare belts for it due to an amazon mix up. So I welded the old clutch lever directly on the cvt arm. Then I added a little catch to hold it disengaged. Depending on how it acts when I start testing, I may add a little friction slide to hold it in place where I set it.

The motor-cvt belt is brand new, so it was super grabby when turning it by hand. So I welded on some rebar pins to hold it loose when it's disengaged. You can see them in the above picture. I figured rebar keeps to the aesthetic.




Also, I welded the front axle rigid. I had to cut off the little tabs on the top to get my welder in there, unfortunately. But now it's quite solid. Eventually I want to extend the front axle and add some suspension some day. Remember, this is supposed to be a road vehicle, and I'm not going to be doing hard turning, so it's a lower priority. I'll see how it handles.

I also flipped the engine plate around and added some tack welds so it wouldn't move around while putting the engine on. It looks like this plate was just flame cut and thrown on, as two of the edges were just horrible.



Since the motor-generator and the gas tank can't coexist on the engine, I had to mount the gas tank somewhere else. I ended up bolting it to the front, but I might eventually move it to under the seat on one side. Since it's now lower than the engine, I got one of those vacuum operated fuel pumps. Should I install this pump up by the carb, or down by the tank?



I originally didn't like the way the engine looked on the vehicle. It seemed like a big engine just stuck on the very front of a little frame.  The engine stuck out like a sore thumb. However now that I have the gas tank in the front instead of on top of the engine, the lines flow better. Like a sine wave instead of a square wave. Putting a rack on the front with lights will also help.

I'm getting close to being able to do a driving test! I need to plumb in the gas tank, and hook up the rear brake to a brake pedal (that I also need to make). Most of the heavy fab work is done for now though. I suppose technically I could try it without a brake, but that just seems like a bad idea.

Looking good man nice work! You must be excited for a test drive!  In my opinion the fuel pump should be closer to the engine, I believe (but could be wrong) that they pull better than they push. Any pulse pump/mechanical pump I've seen mounted in a factory location no matter what's it's been on is nearer to the engine than the tank.

You have enough fabrication skills, I would suggest making Springer spindles.
Way easier than suspension and for on road use more than enough if built well

Springer spindles would be perfect. Revamping the steering and axle is on the list of things to do. The current wheels just have plain bearings, and the original linkage that connects the two hubs has worn out ball joints that aren't replacable. So overhauling that whole mess is on the list somewhere between wiring in a regulator and starter solenoid, and putting on lights.

I may have a problem though. I was running some numbers on speeds and rpms and drive ratios and I don't like what I see. Take a look for yourselves.



I think I need to gear it down a good bit more. An engagement speed of 11mph seems way too high for a belt clutch, and I will never take this to 87 miles per hour! The numbers aren't much better with an 8 inch jack shaft pulley, I think I'm going to look for a 10 inch pulley for the jack shaft.

Of course, this is all theorycrafting, and maybe when I actually try to drive it, I'll find that the engine pulls at 600rpm. It is a big fat flathead after all. I don't know what the hp rating is as the name plate is long gone, but I think it looks a little bigger than a similar 8hp flathead I have in the barn.

edit: Looks like switching the engine pulley from 5in to 3in make the numbers look much better. 7mph at 1000rpm, with room to increase the jack shaft pulley too.

I am not a numbers guy but here's my general opinion.
It seems like too much but it's a very light machine as well.
Though I don't think that 8hp will make it go.

But Iam willing to be proven wrong

Okay, the intake manifold already had a spot where you could drill and tap for a pulse pump, so I did that. I hooked it up and after some cranking, I got fuel to the carbs and the engine runs again! Note to self, replace the points.

However, my suspicions were correct. I tried to engage the drive and it just died out with a lurch. No matter how gently I tried, I could either burn the belt or stall the engine. So my gearing does need to be adjusted.

I'm going to start with a 10in pulley on the jack shaft. There's one in store nearby with the right shaft diameter. That will bring my 1000rpm speed down to 7mph with no other changes. If that doesn't work, I think I'll look at the front and rear sprocket. The current front sprocket is 11 teeth, but I've found you can get down to 10 teeth with a 3/4 shaft. Also, the rear sprocket is like 36 or 37 teeth, so I should be able to find a bigger rear sprocket.

I'm really hesitant to change the pulley on the engine, as it looks like it's on there a little weird. I see some threads on the end of it. Also, that could make the cvt act differently too. Otherwise, I might get a centrifugal clutch for the engine shaft if I decide to go that route.

I still need some brakes too.

It moved! I replaced the 5in engine pulley with a 3.5in pulley and it goes! It's terrifying, yet more stable than I expected. I am super excited.

However, my little minute long excursion down the driveway showed that it just barely qualifies as "working". First, the big belt came off the jack shaft pulley every time I decelerated, since the rear idler was not quite aligned with the rear pulley. Second, the cvt lever needs some friction on it, as I had to hold it in position with some force. I'll probably make a slotted part with a spring on a bolt to make a friction lock to hold it in place. Third, there is no throttle. There's only a lawnmower style rpm lever on top of the engine. Fourth, I need a brake pedal!

So, I need to make a friction slide, and a throttle and brake pedal. Then I can take it for a real test ride!

Well, I had a long weekend, and I managed to get so much done on it!




First things first, results! I managed to go 20mph! It also felt about a hundred times safer at 20mph than the motorized bicycle I used to have. Unfortunately, it exploded (not the engine, luckily).

So, I added a brake pedal, and a throttle pedal! The throttle linkages are a little stiff from disuse and I think there's a missing spring, but as I was using it it got better. I also finally got the belt drive lined up and working. I put a 3.5in pulley on the engine. The crank has no keyway, so I drilled a little hole for one of the set screws to pocket into. Apparently the crankshaft is cast iron, weird! I also welded the original 8in pulley on the jack shaft because it didn't have a key or anything. It was cast iron too, but it welded fine. This turned out to be just the right ratio setup to get going easily.

This engine is a real torque monster, as I suspected it would be! It also seems to be in great running shape. The old oil in it was kinda milky, likely from a leaking dipstick. Fresh oil in though, and even after running for a while it was still so clean I could barely see it on the dipstick. It makes a lovely throaty blubba chunka at idle, reminiscent of a big old stationary engine. Oh, and it has no trouble pulling me around at and even below idle speed.

I like having the carb right in front of me where I can watch and adjust it. The only weird thing is that at moderate load, the butterfly shaft was just bouncing like crazy between open and closed. The engine didn't seem to mind it though. It's probably because the throw of the lever on it is very short, so the linkage only moves like a quarter inch between fully open and fully closed.

Now for the bad news. While I was riding it, just about to go up a hill, it exploded! The cvt pulley snapped off, and the belts got tangled up, and I skidded to a halt. The shaft was only like a half inch in diameter, and only mounted on one side! No wonder it broke. This cvt pulley was always trouble though. It's old and it likes to stick. It's got fixed sides on the ends, and a center part that's supposed to slide back and forth. As you force one belt down, it's supposed to move over and force the other belt (that's spring tensioned) up. But it's very sticky, and I can't seem to figure out how it comes apart.




So I'm going to take a look at this pulley, and see if I can modify it. If not, I'll replace it with something different...

My idea is to replace it with a fixed 3in pulley for the drive side. For the engine side, I want to get the driven pulley from a go kart torque converter. This is basically a spring loaded cvt pulley. It would still allow me to use a belt clutch, and would act the same as the original cvt pulley. But it would act much nicer.

Once I get this figured out, it's time for the next step, electrics! The next step is putting on a regulator, starter solenoid, and a start capable battery. (The current battery is just a little 7ah spade terminal ups battery for powering the coil.) It will be so nice not having to hook up a jumpstarter pack directly to the motor generator to turn it over.

Not much new. I made a new cvt pulley shaft on the lathe at work, and then spent the whole weekend futzing with the pulleys and belts. I did find out that the cvt pulley is pressed together, and when the shaft broke, the press fit moved so the two outer parts were farther apart than they were supposed to be. This was causing me to have all kinds of trouble because the belt would fall in and get pinched. I managed to press them together to the point where there's no cvt action, and it works, but the ratio is steep and it's hard to get going. The clutch lever is very sensitive.

I think all this trouble has soured me on this belt drive setup. I think I'm going to try to just replace it with a 40 series torque converter. The hard part is that the engine shaft doesn't have a keyway.

I really don't want to take the whole engine apart to bring the crankshaft into work to machine a keyway. I could try carefully grinding one in. I don't have a torque converter in my hands so I'm not quite sure how they mount on the crank shaft other than an internal key. If it's steel I could weld a clamp collar onto the driving clutch. I've had really good experiences welding a clamp collar onto sprockets and stuff.

Does anyone have any ideas for attaching a torque converter to a keyless shaft?

In the mean time, I got a small powersports battery, and I'll work on wiring up the starter. Also, I really need to figure out how to tighten up the steering. The steering wheel has about 30 degrees of free play. While that was fine when I drove an old suburban, it's quite unnerving when driving something that could tip over more easily.

Well, I got electric start hooked up. It's very nice to not have to use a jump pack. I even found a cheap solar charge controller board that I had laying around that I could use as a charge controller to keep the battery topped up. The motor-generator rotor winding is hooked to the battery through a diode, and the charge controller board controls power to the stator. When the battery voltage drops to 12V, it turns power on to the stator, and when it rises to ~14.5V it cuts off. It doesn't have the current limiting feature that the original motor-generator controllers have, but it was just laying around in my junk box.



So I noticed that the governor was kicking in way before it was supposed to according to my gearing calculations, the speed, and such. So I adjusted the governor linkage and such, and it does better now. I also got a Very terrible tachometer to double check. Well, it did help. I found out that this little engine has so much torque that it can pull me around at 800 rpms with plenty of throttle to spare. (all the nameplates are missing, but I think it's a 12.5HP). Also adjusting the governor revealed that before I go any faster than say 20mph, I need to fix the loose steering and get a helmet.




Also, the governor is sticky. It has a hard time holding a specific rpm, instead it kinda goes up and down. I'm thinking maybe the seal on the governor lever itself is old and binding up. It's really funny though when you're riding the sticky governor on a moving vehicle. You hit the speed where the governor kicks in and start slowing down, then at some point you start speeding back up, in a very silly fashion. I'll have to do something about this.


So, the steering: The reason the steering is so bad is because the sleeve on the big gear is a very loose fit on the little shaft it rides on. So I'll probably take the gear off and machine a bushing to tighten that up this week.


We are almost to the point where we can reliably ride it around!

Looking good.

For more serious use I would however get rid of this steering setup and look for another option.
there is always some play in there and considering you are going for high speeds this will be crucial.

Also, just pull the governor out, you'll probably do that sooner or later anyway.

fbisurveilancevan wrote:

Looking good.

For more serious use I would however get rid of this steering setup and look for another option.
there is always some play in there and considering you are going for high speeds this will be crucial.

Also, just pull the governor out, you'll probably do that sooner or later anyway.

I second pulling the governor out, there is a reason they don't have them in cars, they are really just for keeping a set RPM for hours on end to run a PTO attachment, not for the constantly varying speed of high speed road use.

rolphill wrote:

Also, I really need to figure out how to tighten up the steering. The steering wheel has about 30 degrees of free play. While that was fine when I drove an old suburban, it's quite unnerving when driving something that could tip over more easily.

Very cool buikd you have going here! Couple ideas I came up with:

-Have you checked all the ball joints? When loose you get a lot of slop.

Your gears look really good. I think that’s fine for now (ie testing purposes)

-sometimes the front axle bushings wear out in the king pins or on the pivot pin and this gets really bad quickly. You might try putting some load or resistance on the steer axle and check to see if the rods are moving more than the kingpins, or the axle is walking back and forth.

I loved the read, This thing has really progressed from stage 1 to now, keep it up and keep us updated id love to see where this goes, props to you for not saying screw it and never touch it again or sell it on fb marketplace, i would have stopped a long time ago if i was making it

As far as the steering goes, the ball joints that connect the two hubs to each other need to be replaced. They can pop off with some force, but there's no play. The ball joint that attaches the steering rod to the left hub only needs replacement because the rubber boot is cracked. The gear teeth mesh really well, as well as any go kart rack and pinion I would buy. It's just that one interface between the pin and sleeve the large gear rotates on that's got a bunch of play. Also, all the steering linkages are not adjustable, so that's another reason to replace them. The ball cups are machined directly into the rods. There's also no play in the hubs either. The wheels use plain bearings but they are in good shape.

This tractor has seen a good bit of use, but it was well maintained. The only thing that was really worn out was the friction clutch throw in bearing. It was disintegrated when I got it. The engine is in really good shape, the oil is still crystal clear after at least an hour of running since I changed it. There's evidence of some leaky seals, but that may clear up as it's run.

I also plan on widening the front wheel base. The front axle is a square tube, so I want to find a slightly bigger piece of square tubing that I can use as a sleeve. I should just be able to cut each side and re-weld the sleeve in. I did actually fall over on it hitting a rut in my yard while already on the side of a slope. Luckily I wasn't going very fast.

I promise I'll get some video of it soon.

Oh, here's why my steering is loose:



That pin looks more like a barrel. I'm going to machine the ID on the gear, and make a bushing to press in. I'm also going to cut that pin off and make a new pin to weld in.

The steering is fixed!

I put the gear in the CNC, and probed the outside of the bushing to find where the center was supposed to be. I machined the bore out past the worn parts.


Then I made a new pin with a wide base. This will make it way easier to weld on level. I also made a bronze bushing to press fit into the gear bore.


With the wide base, getting it lined up and welding it on was a snap.


My steering wheel backlash is down to like 10 degrees now, and its all in the gear mesh, so the backlash at the wheels is nil. It's not squirrely anymore. I took it for a test ride and reached 23mph at 2600rpms. This matches up with my gearing calculations.  At this speed the narrow wheel base is now the limiting factor. It feels a little tippy. So it's time to widen the front axle.

The confirmation of my gearing calculations also means that I'm engaging the belt at around 8mph. The engine doesn't have any trouble getting going, but its a little fast for me and my potholey driveway / back yard. It's also a little too high to comfortably do a powered u turn on my dirt road. I'm going to keep this gearing for now, but when I figure out a two speed setup, my low gear will be a bit slower.

I extended the front axle, and wow it's so much more stable! I went for a 6 mile round trip down dirt roads with NO failures or belts coming off and it's so much better. I can even do a powered u-turn now. I'm getting more used to the belt clutch as well. My takeoffs are nice and smooth.





I'm still working on getting the toe-in dialed in correctly. At high speeds it likes to kinda... jump? left and right sometimes. Adjusting the toe helped, but I need to do more testing. However, that may also have to do with the very crowned, pebble covered dirt roads I was riding on. I need to try out a paved road to see how it does. I also need to look into the lever that the steering rod attaches to on the left hub. I'd like the steering to be a little less sensitive, so I want to make that longer.

I think I also need more caster. It could use more self centering. I'm not sure how to easily do that besides grinding and rewelding the axle parts back together.

Also, I think I've decided on my two speed transmission. I'm going to have two pulleys on the engine, and two pulleys on the cvt/first jack shaft. They'll be lined up opposite, like the pulleys on a lathe or drill press. I'll come up with some sort of mechanism to bump the belt back and forth. The numbers on this method look really good as far as speeds go. A 3.5in/5in combo gives me 6-27mph in first, and 12-56mph for second.

Looking good man! Glad you're putting some seat time in!

Enjoy!



So I managed to do some testing on a paved road. I hit 30mph! The engine purrs like a kitten, although I think it's running a little rich still. I also need to route the exhaust away, as it pops painfully loudly if I don't let off the throttle slowly.

Most of my instability issues were actually down to the dirt roads I was riding on! I got the toe dialed in so that it's quite stable on a paved road. However, it wants to wander while I'm decelerating. The wheels have a good bit of play on the axles (plain bearings). I think that's the next source of instability. I will likely end up having to redo the whole front end with new parts.

Oh, and I didn't like any of the speedometers I found online that weren't super expensive. They're all gps based. So I made my own speedometer using an analog needle meter, an attiny85, a hall sensor, and a magnet on the jack shaft. I had a lot of issues with ignition noise interfering with the microcontroller, but that's a topic for a different forum. In any case, I got it working most of the time, and it matches up with my phone speedometer. The meter is 0-5mA, which corresponds to 0-50mph.

On another note, I think I finally got my motor-generator working right. I think my next step is going to be a mirror and lights, while upgrading the wheels will be a winter project.

Not much progress, it's been cold and rainy, and I've kinda hit a couple roadblocks.

First, I did successfully cut and reweld my front spindles to give me more caster, somewhere around 10-15 degrees. It helped a little, but didn't help nearly as much as I was expecting. I'm pretty sure this is due to the large amount of play in the wheel bearings. When I'm going at a constant speed on level ground you can actually hear them bouncing around. I think I'm going to start with machining some bushings for them, but I will need to replace the wheels (and spindles) entirely anyways. It's really hard to find wheels and spindles that I can add a brake to AND can fit a common DOT approved road tire. The current wheels are just the right size for cheap trailer tires, but they have plain bushings. Now I'm sure plain bushings would last much longer than my attention span, but I HATE plain bushings because they wear loose.

The other problem is that the field coil on my starter-generator went bad literally right before the mechanical regulator I ordered arrived. This starter-generator has a separate stator coil for starting, so it still works as a starter thankfully. Also, since it still has a stator coil, it does make a bit of voltage (at high current). It's just not a high enough voltage to charge the battery directly. A new set of stator coils is available, but expensive, at $80 on ebay. Until then, I'll just have to keep my test rides somewhat short, and remember to put a charger on the battery after every ride. I want to try experimenting with a voltage boost circuit to take the low voltage put out by the generator and boost it up to charge the battery. I already have all the parts for it laying around. It probably won't be able to put out enough current to power lights, but it should be able to maintain the battery over the ignition coil draw.

For the brakes and front hubs, how about an old four wheeler? The Chinese ones can be had dirt cheap and a bigger Yamaha or Honda etc. Could probably be found in an atv junkyard. You could get independent front suspension while you’re at it too.

I'm leaning more towards a trailer wheel or similar. The hardest part is making sure the wheel fits a common highway tire size. I've found cheap go kart brake calipers, which will be good enough for now. I can machine my own spindles better than what I've seen on go kart parts websites, and I can make brackets for a disc brake to mount up easily enough, and probably the disc too. I'll have plenty of time to do that this winter.

Oh, on a positive note, someone identified my engine as a 16HP briggs flathead. That explains the large torque at low speeds. That's plenty enough horsepower to get me to highway speeds without any trouble. I also have a close enough model number to get replacement parts if I need them.