Free Subaru EX21

[Kentucky Boy]

My best friend recently gave me an old John Deere pressure washer with a 7hp Robin Subaru EX21 motor. He said he bought this thing in 2005, used it for two hours then left it sitting in his barn for the past 14 years. He gave it to me because “it doesn’t work”. The throttle and governor arm were rusted into position and the carb needed rebuilt.

 

[Kentucky Boy]

I quickly removed the motor to diagnose its problems. I bought a $15 new carb and used the parts out of it to rebuild the original Mikuni that was on it. The throttle plate lever was rusted and would not move. That’s the only thing I found wrong.

 

[Kentucky Boy]

It was pretty dirty and rusted so I planned on disassembling it to give it a makeover. I took the head off to inspect the piston, cylinder and valves. All was good. These are really well built motors. I cleaned the piston and combustion chamber then lapped the valves.

 

[Kentucky Boy]

I cleaned it up and painted it. I also cleaned up the coil and the flywheel and painted the flywheel.

 

[Kentucky Boy]

This motor is going back on the pressure washer but may be used on a future kart build. There are good parts available for the EX Robin such as an ARC billet rod and flywheel. I might get an EX 17 head to put on it for a compression bump.

 

[JTSpeedDemon]

Overhead Cam right?

 

[Tpdingo]

Overhead Cam right?

OHC doesn't mean Overhead Crap.

 

[JTSpeedDemon]

Thank goodness, but I'd rather not deal with a timing chain.
Good ol' gear driven flathead!
Although I would love to tinker with a Subie.

 

[mckutzy]

Kinda like those GC Honda's in a GX but an amalgamation of the two....

 

[Kentucky Boy]

Thank goodness, but I'd rather not deal with a timing chain.
Good ol' gear driven flathead!
Although I would love to tinker with a Subie.

I’ve got plenty of flatheads. This is a way better motor than a flathead and even better than a Predator. Here’s a look at the cam.

 

[JTSpeedDemon]

Yeah, Carsandcameras mentioned the one lobe cam. How's it run with that?

 

[Kartorbust]

Looks like the rockers (for ease of explanation) sit close enough together that it only needs one cam lobe. https://www.youtube.com/watch?v=vENlQaFcT2c

That should help give a visual explanation.

 

[Kentucky Boy]

That’s a great series of videos for the EX motors.

 

[Kartorbust]

Thank goodness, but I'd rather not deal with a timing chain.
Good ol' gear driven flathead!
Although I would love to tinker with a Subie.

I'll take a timing chain over the Honda GC timing belt. I do prefer timing gears more than chains...tendency to be more reliable (automotive standpoint), regardless though, if I could find one, I also wouldn't mind messing with one. But the stock carb would be coming off and slap on a mikuni.

 

[Kentucky Boy]

I'll take a timing chain over the Honda GC timing belt. I do prefer timing gears more than chains...tendency to be more reliable (automotive standpoint), regardless though, if I could find one, I also wouldn't mind messing with one. But the stock carb would be coming off and slap on a mikuni.

They come with a Mikuni stock carb. But a larger Mikuni would really wake it up. The timing chain appears to be high quality and could probably take a lot of abuse. This is a very nice motor. It even has cooling fins on the side of the block and on the bottom of the motor.

 

[JTSpeedDemon]

Agreed with both of y'all.

 

[KartFab]

This timing chain in my honda civic has been holding on for 180k miles. I like the little subaru engines, they are very efficient and quiet. They make great power for their cc's as well with the piston to valve clearance and head design. Very well built. As long as I dont have to buy parts for one, Im happy with them. Ridiculously expensive replacement parts.

 

[65ShelbyClone]

Timing chain systems that are properly designed typically last the life of the engine.

Subaru's EX line are very nice utility engines. I had an EX27 for a while that was every bit as good as a Honda GX and maybe even smoother and quieter. I didn't keep it because the single-lobe cam seriously limits upgrade potential. And yes, the rockers follow it on the same path so there's no real way to retrofit with dedicated intake and exhaust lobes.