Project Super Sport Mower

I made mention of this idea a while back and now i am getting it started. My idea is to put a Honda CB550f super sport 4 cylinder street bike motor in a mower. I have a Craftsman mower that had a 16 hp briggs originally. I am actually surprised how well the frame is built so it will be good for the job. My plan is to cut the frame out enough to get the motor to sit around three inches down in the frame. The hood totally covers the motor perfect. With the hood on you really cant tell the motor is in it. Im going to lower the mower 4 inches and move the front axle forward for stability. I will get some pictures up real soon.

I wanted to put a twin cb400 in my mower, but I was way ahead of myself, but I have a good idea of how everything will work. Post a lot, I really want to see this thing!

Holy smokes! That hood swallows it right up doesn't it!

Make sure you make accommodations for air flow... those air cooled motors will get hot in a hurry without it.

Wow! Thats gonna be insanely fast!

Like TRB said, youll need airflow. You might need a few 6" radiator fans.

What bike was the motor out of?

Make sure to build a super duty front end/steering.


That would be a crazy sleeper tractor.

Some Swedish guys did the same but with a beast Hayabusa Engine.

Holy cow! You could make scoops in the side of the mower and take out the headlight, Thad be good cooling.

I am thinking about putting a cooling fan out of a car to help cool the motor. The steering is going to get worked over very well.

the motor came out of a 76 (i think) Honda CB550F. Its been a while since i have had this motor running but i think it will come right to life.

These engines depend a lot on oil cooling. Make sure you have lots of air flow to the oil filter. If you can find one, an aftermarket oil cooler is a big help.

At least its a wet sump engine, so you won't need a separate oil bag.

pulled all the body parts off this morning and did bunch of measuring for the various parts i need to make. Then this evening i moved the front end all the way forward almost 10 inches and dropped it 3.5 inches. And mocked up the rear end just to see what it will look like dropped 3.5 inches and 4 inches wider. some thing major is bound to go wrong, this build is going way to easy so far. Next up i am going to cut the frame so the motor can set lower and get a rear axle machined up.

Lol! this is you when you finish this https://www.youtube.com/watch?v=3KIGix5OsDk

That is funny, only thing is i will be able to pass that guy up.

a couple of hours of cutting and the motor has its new home. Making the exhaust clear was a huge pain in the captains quarters. Now to fab up the motor mounts, finish running the exhaust and machine the rear axle. I cant wait to fire this thing up.

just looking at it you can really tell what lurks under the hood.

And i have found a oil cooler for this motor that the racer guys use. I can get one off ebay pretty cheep.

redlinemotorsportts wrote:

Lol! this is you when you finish this https://www.youtube.com/watch?v=3KIGix5OsDk

Did you hear that differential screaming? 20 bucks says he's only got grease in there...

prometheusEDI wrote:

redlinemotorsportts wrote:

Lol! this is you when you finish this https://www.youtube.com/watch?v=3KIGix5OsDk

Did you hear that differential screaming? 20 bucks says he's only got grease in there...

I was expecting to see him crash.

Got a little bit done today. I have a master cylinder and brake caliper set up. The master cylinder is one for a race car that i bought years ago.
The caliper is off a street bike of some sorts. I figured out a good way to mount the master cylinder that uses the original brake pedal. Hoping to get over to the machine shop and get the rear axle machined up real soon. I also need to machine a hub for the brake disc to mount to.

prometheusEDI wrote:

redlinemotorsportts wrote:

Lol! this is you when you finish this https://www.youtube.com/watch?v=3KIGix5OsDk

Did you hear that differential screaming? 20 bucks says he's only got grease in there...

And sloppy bushings, amongst other things

Got allot done today. Exhaust is tacked together, made it out of 2.25 inch pipe U bends and a dual 2 inch tip. I had to put some bends in it to clear a couple of things.

Got the throttle pedal mounted, and started working over the steering. I found out that the steering was hitting every thing. It hit the motor mounts, hit hit the bottom of the motor. but i have it figured out how to fix it. It will take a trip to the machine shop.







so far so good.

Looks good i like the exhaust.

This is by cool. I can't wait to hear the sound of this thing screamin at 11k

BIG UPDATE every one. I have been burning the candle at both ends. working two jobs, the wife and kids, and my super sport mower. I have been busy.

I have a rear axle now. Its 36 inches long, 1 1/8 inch in the middle stepping down to 1 inch the stepping down to 3/4 inch and threaded on the ends. I liked the idea of having the ends threaded so the wheels could be held on with nuts. I have about 10 hours of machine time in the axle and another 2 or 3 more to go. I still need to cut key ways in it for the wheels, sprocket hub, and brake disc hub. The axle is on 1 inch pillow block bearings that bolt to some 1 1/2 inch square that is welded to the frame.

I have a 32 tooth sprocket for the rear.

I found a oil cooler for the motor. I need to get the motor over to my dads machine shop so i can make an adapter for the oil filter to run lines to the cooler.

I also have the motor all mounted down. I took me 2 or 3 days to figure out how to get the thing perfect square to the frame.

I bought 5/8 and 1/2 inch heim joints for the steering. A little over kill but thats never a bad thing. the 5/8 joints go from the steering box to the spindle on a 5/8 shaft that has been threaded. the the 1/2 joints tie to two sides together on a threaded 1/2 rod.

I had problems with the steering arm on well i call it the steering box hitting the bottom of the motor. So i had to cut the arm off and the big steering gear off the original shaft and make a new shaft that i 2 inches longer. Now it clears the bottom of the motor and just misses the exhaust. I also had to move the front of the front end since i lowered it and the frame is now in the way. How i did that was i cut the arm off the spindle that connected to the rod to the steering box and welded it back on to the other spindle then switched the two spindles around. Hope that made since. Any way there is no play in the steering and it works very smooth.


I made the original lever that raised the mower deck up and down into the shifter. with a rod with 3/8 heim joints running to the shifter on the motor. on the handle is a motorcycle lever that is the clutch.

I still have allot to do, plenty of finish welding. once every thing is mocked up i can figured out all the bracing for the frame. I need to get a brake disc ordered, and get some ignition coils and some carbs put together for the motor. And do all the electrical work.



And now a bunch of pictures.



Axle



nuts holding on the wheels



My shifter linkage



Modified steering box



Tie rod moved to the front to clear every thing





Check out the stickers

Thanks guys, this is one of my best builds yet.

I like it.
I like the way it looks.