So this is my first time posting here and I’m hoping it’s in the right section. I have a project in mind that I have been thinking and needed some advice and help. I want to build a manual lawn mower kart with the engine that is already in there. I know this will be hard but if I can get a cheap frame with a high torque engine that would be the best think for my savings account. My main questions are how do I redirect the shaft, where can I get a manual clutch and is it possible to use maybe a transverse civic trans or maybe a Miata trans? Or is there some band that sells maybe a sub $600 3 spd sequential trans for karts? One that can take the 30 ft lbs of torque from the brigs v-twin? Thanks in advance.
Vertical shaft kart
- Thread starter Brigsman
- Start date
mckutzy
Well-known member
Hello and welcome....
Kinda a tall order....
First.. a vert engines arent really meant to be run in the horizontal position. albeit a few have converted to work for the horizontal position... most give up...
A "cheap transmission" doesnt exist for karts, mainly cause a gear shifting with clutch transmission in a typical Shifter kart, is a motorcycle engine to begin with.
A Motorcycle is about the best option off hand to start with, as it will have all things needed to start and go with... then is just hooking up a drive line and go....
Kinda a tall order....
First.. a vert engines arent really meant to be run in the horizontal position. albeit a few have converted to work for the horizontal position... most give up...
A "cheap transmission" doesnt exist for karts, mainly cause a gear shifting with clutch transmission in a typical Shifter kart, is a motorcycle engine to begin with.
A Motorcycle is about the best option off hand to start with, as it will have all things needed to start and go with... then is just hooking up a drive line and go....
Thanks for the response. A motorcycle engine would be nice but they have too much power. thought about an 85 2 stroke. My thing with that is I have no idea what condition the engine is in, I have dealt with race engines a lot and I don’t want to deal with the radiators either. The v twin brigs is a solid engine. I would give up the trans I would just love to have the v twin. You might have misunderstood what I was saying about the engine. I meant is there a way I can run it vertical but mount some kind of 90 degree gearbox to the shaft on the bottom. If I wanted to run a differential, is there anyone that sells an in-line clutch? Also, I tried to do some research on lawnmower karts and have not been able to find much. How have others gone about this?
Kartorbust
Inmate #627
You could just scrap using a manual transmission from a vehicle and just build a yard kart race mower. Until the horizontal shaft singles and twins became popular, vertical shaft engines were used in mower racing. The either used a go kart centrifugal clutch to the input of a 90⁰ right angle gearbox with a sprock output to a live axle on the rear. Here's a DIY race mower that was used to race to give you ideas, instead of trying to mate a transmission or transaxle to a custom frame. https://www.instructables.com/id/How-to-make-a-racing-lawn-mower/
Ok, that article gave me a really good insight on the vertical to horizontal transfer. Main thing now is how would I mount the trans in a way where the shifter is accessible? To give you an image of what I am trying to do , I basically want a sleeper, a dropped lawnmower without the deck is all I’m shooting for.
ol'joe
Member
You also need to know that on rotary mowers, the blade serves as a flywheel. Take the blade off of a rotary mower and try to start it, it tends to roll up on the compression stroke, the engine fires but bounces backwards, the starter cord wraps up on the spool, cord stretches, snaps, cord handle goes through a window at about 30 MPH.
This happens if the flywheel is aluminum. Cast iron flywheels work just fine with no blade on the crankshaft. If a magnet will stick to all parts of the flywheel, you are home free, and some riding mowers have iron flywheels, but you gotta check before cranking.
Aluminum flywheels with no blade on the shaft tend to stretch tendons on the hands that pull the starter cords, too. HURTS!
Take care....Joe
This happens if the flywheel is aluminum. Cast iron flywheels work just fine with no blade on the crankshaft. If a magnet will stick to all parts of the flywheel, you are home free, and some riding mowers have iron flywheels, but you gotta check before cranking.
Aluminum flywheels with no blade on the shaft tend to stretch tendons on the hands that pull the starter cords, too. HURTS!
Take care....Joe
The engine I’m planning on using would not have a pull cord and definitely not an aluminum flywheel. I want a powerful kart and as I’ve said the 20hp brigs v-twins that come in the little John Deere’s are perfect, so I shouldn’t have to worry about any pull cords, but that is good to know if I ever wanted to try this on a smaller scale.
anickode
Active member
That's not so much the case with riders or bigger walk behinds, since the engine needs to be able to run without the blades spinning.
On the topic at hand, why not simply remove the mower transaxle, put a jackshaft in the rear, and run a twisted belt drive from the mower engine to the jackshaft? You could put a pulley centrifugal clutch right on the engine, drive to the jackshaft with say, a 2:1 or 3:1 reduction, then slap a solid go kart axle underneath it with a chain drive to get your final reduction?
Or you could get even more creative and run a fixed pulley on the engine, to a jackshaft at a 1:1 ratio, then put the centrifugal clutch (or even a torque converter) on the jackshaft, driving a kart axle.
Twisted belt and mule drives are INCREDIBLY common on riding mowers... It's how mowers with horizontal shaft engines run mower decks, and it's now vertical shaft engines run things like snowblowers. They work quite well, and when you have the engine in front, there's plenty of room to set one up.
ol'joe
Member
If I were running a belt from the engine, no way would I mess with a centrifugal clutch. belt idlers work SO much better, in my opinion.....Joe
@anickode, I like that belt idea a lot, probably the easiest way to get it done. My question now is if I bought a 1” axle for the jackshaft would I be able to slip a 1” clutch on it? Also does anyone sell a high horse power manual clutch for karts? Thanks in advance
anickode
Active member
Yes.
No.
For a manual clutch, your best bet is a belt tensioner setup as ol' joe mentioned.
Brianator
Gettin' er done!
Sounds like you're over complicating the whole setup imo... get a 200 or 250cc 4 stroke engine from a dirtbike, atv or atc and be done with it. Roughly the same displacement and power levels as what you're talking about plus it already has a transmission. They can be found in full manual, semi-auto and full auto, with electric start and a pull start backup ect ect ect so many choices....
mckutzy
Well-known member
Thats what I was saying..
Brianator
Gettin' er done!
Yup!
I really don’t want a motorcycle/dirt bike engine for a couple reasons. Price is a major factor as well as reliability. For the money nothing is better than an old brigs on a lawnmower. They are very reliable, electric start and can generally put out 30+ ft lbs of torque. If I would ever use a motorcycle engine in a kart I would only use an air cooled 2 stroke from the 70s/80s, but they’re too much work to get a hold of so I’m going with the next best option. So to covert the shaft I use a twisted belt set up, but for the clutch I want the belt tensioner clutch as previously mentioned. Seems the easiest/cheapest way to do a manual clutch. I’m at a cross roads now because I don’t know how to combine those. I could have 2 jackshafts but that seems excessive, too many moving parts. A 90 degree gearbox would fix my problem but they’re pretty expensive. Thanks for the responses