A friend has imported one of these and there's a chance I might be able to pick it up from him. My riding buddy says the red 303 is a late effort hodge podge of parts and that the transmission is a time bomb.

I know very little about these bikes.

Is the bike a museum piece?

If the tranny is fragile, are there options?

No idea why he told you that about the gearbox, the 303 shares the same engine components as the TR80 Gripper and MAR trials bikes plus numerous other models.

Not really describable as a hodge podge either, it's basically an evolution of the TR80, with frame changes presumably eradicating the weak points where they could break. The engine is TR80, exhaust is TR80 redesigned to go over not around the cylinder and a new slimmer tank seat unit was fitted.

Thanks, Woody.

my riding partner picked up an orange 250 Gripper a couple of years back and the bike is absolutely beautiful. It's original and could pass for new. It resides in his basement for display. 

Then a few months ago another friend came to town for a visit and saw the bike and lost his mind over it. He's an importer and next thing we know he had both an orange 250 and a red 303 sent from Italy. The 250, while not nearly as nice as the one in the basement, still thrilled me. The red 303 came from an Italian fellow that kept it on hand for Mick Andrews to ride when he visited. I have a photo of Mick on the bike somewhere and will post.

So my friend the importer said he was going to ride both bikes and keep one. Turns out he loves the 250, so I ask what he wants for the 303 figuring he'd ask some crazy price. His reply? Hell, you can just have it....... Well, Dad said never look a gift horse in the mouth, so I graciously accepted. 

The friend with the museum 250 tells me I should garage it. Even though he just bought a sweet 240 SWM, I'm going to insist he ride it in some events. Me? I'm a Bultaco guy, while he's an Ossa nut. Besides, no one takes better care of a bike than him. He's one of those guys that gets his bike looking new after a ride while mine looks like you'd expect.

 

I took possession of the 303 last Saturday. Runs a bit rough, though. The carb appears to be a Mikuni. Does anyone know if these were standard? 

Looks great!

    My understanding is the biggest issue with the OSSA gearbox in general is if it has improper shimming. They are sort of time consuming to properly shim (so I understand, I’ve never done it).