Ross Pistons Size
- Thread starter johan
- Start date
TinTin
Full member
- Location
- the low lands
don't go for the last size directly... but buy them if they are cheap enough for future bores...
What's your bike?
What's your bike?
Johan,
I stock Ross Hi-Comp Pistons in 80.5, 81.0, 81.5, 82.0, 83.0mm.
A 80.0mm+ Ross Hi-Comp pistons weighs within 4-5 grams of a 75.0mm Mondial tractor piston so crankshaft balance is not affected when changing to large bore.
If crankshaft balance is a worry then the problem occurs when you change from 75.0mm Mondial tractor piston to a 75.5mm Ross, the piston weight is a lot lighter.
In reality, all you are doing is changing the factory balance factor by a few % +/- and there is no vibrational change to the engine that we have ever been able to tell.
I stock Ross Hi-Comp Pistons in 80.5, 81.0, 81.5, 82.0, 83.0mm.
A 80.0mm+ Ross Hi-Comp pistons weighs within 4-5 grams of a 75.0mm Mondial tractor piston so crankshaft balance is not affected when changing to large bore.
If crankshaft balance is a worry then the problem occurs when you change from 75.0mm Mondial tractor piston to a 75.5mm Ross, the piston weight is a lot lighter.
In reality, all you are doing is changing the factory balance factor by a few % +/- and there is no vibrational change to the engine that we have ever been able to tell.
Hi .Thanks for anser, but i?m still in some ??
I found this info on laverdamainia "the biggest recommended size is 81mm in order to keep
the required liner thickness. If the 81mm size is chosen, it is necessary to adapt new liners (the Citro?n BX liners can be adapted to the
Laverda block) and to fit new forged 81 mm HC pistons "
Does this meens that i?m in the edge off what the liners can take, if I go for my friends 81 pistons( Re bore a 1200 cylinder)
Would it be better to buy 80.0 pistons and re line the worn 1200 cylinder?
Johan
I found this info on laverdamainia "the biggest recommended size is 81mm in order to keep
the required liner thickness. If the 81mm size is chosen, it is necessary to adapt new liners (the Citro?n BX liners can be adapted to the
Laverda block) and to fit new forged 81 mm HC pistons "
Does this meens that i?m in the edge off what the liners can take, if I go for my friends 81 pistons( Re bore a 1200 cylinder)
Would it be better to buy 80.0 pistons and re line the worn 1200 cylinder?
Johan
Johan,
I'm running 82.0mm in my road bike on standard liners no issues at all.
Outside diameter of the liner is 86.0mm, leaves a wall thickness of 2.0mm per side, plenty of meat.
For the 83.0mm pistons I change Liners to custom Liners that I had made at LA Sleeve in USA which have an OD of 88.0mm and which I have in stock
We are running both the motors in the Oz Laverda Spaceframe at 81.0mm, not having piston or liner issues with those engines.
Also consider that a fairly common big bore size for the 1000's is 78.0mm, is the size that the Laverda Corse Team race on.
They are using standard Liners which are 82.0mm OD, thus they are running a wall thickness of 2.0mm, no issues at all.
I generally use 77.0mm as the maximum bore size on a 82.0 OD Liner for the street which is 2.5mm wall thickness.
We are constantly using 81.0mm on standard Liners without any problems at all so I do not agree with that statement below.
Regards
Red
I'm running 82.0mm in my road bike on standard liners no issues at all.
Outside diameter of the liner is 86.0mm, leaves a wall thickness of 2.0mm per side, plenty of meat.
For the 83.0mm pistons I change Liners to custom Liners that I had made at LA Sleeve in USA which have an OD of 88.0mm and which I have in stock
We are running both the motors in the Oz Laverda Spaceframe at 81.0mm, not having piston or liner issues with those engines.
Also consider that a fairly common big bore size for the 1000's is 78.0mm, is the size that the Laverda Corse Team race on.
They are using standard Liners which are 82.0mm OD, thus they are running a wall thickness of 2.0mm, no issues at all.
I generally use 77.0mm as the maximum bore size on a 82.0 OD Liner for the street which is 2.5mm wall thickness.
We are constantly using 81.0mm on standard Liners without any problems at all so I do not agree with that statement below.
Regards
Red
motoddrob
Hero member
- Location
- S/W Australia
Isn't 81mm standard 2nd O/S??
motoddrob
Hero member
- Location
- S/W Australia
Learn something new every day Piet!! When I asked for 2nd O/S Ross pistons from Wolfgang they measured 81mm so assumed that was the size!!