What application do you have in mind for a 125mm rod?
SF
It is a project we call "The Blair Witch". It is a 275cc LC case inducted barrel, it is 60 stroke and 76mm bore with a JS650 piston We've cast 3 to date and building the second engine. The crank config will be 58 stroke with the 22/24 eccentric pin to make 60 stroke but with as much meat around the pin as possible. The first engine was 58 stroke 76 bore and gave about 35bhp as I remember. You really need a bigger rod for that type of top end.
Impressed! You don't to things by half, do you?
How are you engineering a case inducted Lambretta block?
What application do you have in mind for a 125mm rod?
SF
It is a project we call "The Blair Witch". It is a 275cc LC case inducted barrel, it is 60 stroke and 76mm bore with a JS650 piston We've cast 3 to date and building the second engine. The crank config will be 58 stroke with the 22/24 eccentric pin to make 60 stroke but with as much meat around the pin as possible. The first engine was 58 stroke 76 bore and gave about 35bhp as I remember. You really need a bigger rod for that type of top end.
The first case was fabricated largely by hand, with quite a long inlet track. The second case is different, it has a CNC machined base gasket block that is welded in and the plan is the same for the case read which will fit in the same area (closer to the crank than the first case). These first two engines are very much works in progress, between myself and Mr Topper we are optimising the product development to be as cost effective as possible. Essentially, what we hope to achieve is a highly cost effective 275cc LC motor with between 35-40bhp (there would be potential for more but as Sticky pointed out, other development costs are required such as rear axel and hubs etc, the current parts would be sweating enough with the power as it is).
Ultimately, we are looking at achieving a highly cost effective specification with GT crank (60 stroke, 125mm rod), RS125 ignition, Cast iron Blair Witch cylinder and modified casing with CNC blanks welded into a pockets that have been CNC cut into the existing case (this is a process that Guy has been working on).
I cast 3 cylinders (2 aluminium and one iron) and 3 aluminium cylinder heads. We don't see a huge market for the conversion, maybe half dozen per year tops in reality, but it will be an interesting process in how much we can optimise the commercial side to make this type of format a viable for more people.
First cranks are being fitted this week. 58 stroke with 110 rods, full circle and mathematically balanced. CNC machined new Indian webs and CNC nylon inserts provides a cost effective and consistent production part. Production rods will be 110 (16 pin, 58 & 60 stk), 115 (16 pin, 58 & 60 stk) and 125 (18 pin 60 & 62 eccentric pin). Original GP crank weighs 2.07Kg, New GT crank weighs 1.96Kg
You don't to things by half, do you?
its the red GP in my latest few videos.