Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board Running two right hand con rods on an A65

The subject of running two right hand rods came up in Adam M's thread about his friends high mileage '72 A65, where he said he friend had blocked the drilled oil holes on the left hand rod. I notice that in the 'Thunderbolts & Lightning' book it's mentioned (page 84) that the BSA competition department recommended using two right hand rods instead of the drilled left hand rod.

I don't see the advantage of the drilled rod, except maybe spraying oil into the underside of the left hand piston and gudgen pin. Was that a problem that needed fixing? I don't know. I can see the advantage of not using the drilled rod, to keep as much oil pressure in the big end as possible.

Has anyone run two RH rods and developed problems as a result?

Steve.

The drilled rod was a sticking plaster apoach to a problem which eventually raised its head as the problematic 4CA points. They just never changed it back again after. The idea was to spray oil up the bore on the left cylinder.

The map rods have grooves cut away at the side of the rods instead of the holes.

Thunder engineering rods have 1 hole drilled (unless you spec differently)

Thanks Allan. It looks like both the MAP rods have 'notches' cut into them at the TDC point.
Visible here and the 'blurb' goes on to say :

"Innovative machined piston oil squirting notches"
and
"Unlike the stock BSA rods, these rods have been designed without a big end oiling hole because it is not necessary. Other oiling systems take place of the hole in the big end."

Did the steel capped rods used in the A70 have the oil holes drilled?

S.

Rods can split through that drilling. I use them but I would prefer them without, and would not buy them. Two non drilled steel capped rods are very good. So are the rods supplied by MAP which are steel and virtually as light.

The holes are not needed. Having motors run extensively without.

Thanks Mark. I am heading towards the MAP rods for my re-build.