Lightweight pistons reved to the max

Lightweight pistons and longer rods are starting to show on the street and on the tracks. Nort 850s don't need to rev past 7200 but one of the racers was under geared and was buzzing it to nearly 8000. Thats a little beyond reason and I certainly don't recommend it but at least it shows that the forged pistons and special Carrillo rods with DLC coated pins can take the abuse.

See street bikes and racers with the light pistons at:

http://users.gotsky.com/jimschmidt/nortonrodsbikes.html
More will be added when bikes are up and running.

Jim

Very cool. Nice work, good to hear the testimonies. Not like I doubted this would work.

What cranks are these guys running?

I would guess they aren't stock!

Maney's I would assume.

What about drive-side crankcases? I always thought that was the weak link.

The racer I mentioned is getting away with a stock crank for now because the lightweight pistons & longer rods make life much easier on the crank & cases. Most racers use Nourish or Maney crank or some other stronger crank and that is much prefered. However if you cut a radius in the PTO drive side where the stub meets the cheek you can use a Stock crank for awhile. Lightening the flywheel also helps (also in the race manual) and I never broke one with these modifications. But I still cracked stock cases and had to reinforce them with a 3/8 plate welded onto the drive side (lots of work). This was back before Maney cases were available. Buzzing the (850 monoshock) motor into valve float range (racing valve springs) would flex the crank and cause the pistons to kiss the head. But it all held together with the lightweight pistons I was experimenting with back in the late 1980s. Hard as I tried - I never blew a motor. Reducing the reciprocationg weight is everything when it comes to keeping these motors (and evevything else on the bike) together - its good economics.

Jim

Exciting reports plus scary looking bikes with happy racers!
Congrates on setting a new rpm benchmark of endurance.
Don't tell a Nortoneer not to press luck in glee, like you don't too.
Appreciate the crank shaft review too.

hobot - Ozark Ms Peel.