Stroking

[Helen Weals]

Is it possible to Increase the stroke on these motors? Is there enough "meat" on the flywheel to offset The crankpin, use an offset crankpin ,or can it even be done on a 2 smoker without effecting the timing?

 

[rohmell]

No room to increase the stroke any. On some engines, the piston hits the sparkplug at TDC, and an extra head gasket needs to be added, any more stroke and you would have the head flying off into space.

 

[Helen Weals]

I understand there is clearance problem with head but stroker plates or thicker base gaskets would take care of that.I am more conserned how it will effect timing if at all

 

[rohmell]

Members here have changed the timing by simply using base gaskets of different thicknesses, so, yes, the timing will be changed.

 

[kevinkrg6]

This supposedly helps you change timing:
Manic Mechanic Adjustable Timing Magnet

 

[Venice Motor Bikes]

This supposedly helps you change timing:

That's for ignition timing... They're talking about port timing which is something totally different.

 

[GearNut]

There was a member once, a long time ago, who stroked the flywheels by Tig welding the crank pin hole up and machining the hole closer to the edge of the flywheels. He also ran a moped piston, cylinder and head. It was quite a Frankenstein sort of engine, and extremely fast.
He is no longer a member here though, and I cannot find any threads concerning it.
Like I said, it was a looooong time ago.

 

[Goat Herder]

There was a member once, a long time ago, who stroked the flywheels by Tig welding the crank pin hole up and machining the hole closer to the edge of the flywheels. He also ran a moped piston, cylinder and head. It was quite a Frankenstein sort of engine, and extremely fast.
He is no longer a member here though, and I cannot find any threads concerning it.
Like I said, it was a looooong time ago.

http://motorbicycling.com/f13/hybrid-chinese-motors-performance-tuning-14204.html

 

[GearNut]

Thank you Goat Herder. For the life of me I cannot explain why I did not find that.

 

[Helen Weals]

There is a thead here on different pistons could you not use that to increase stoke or displacement?

 

[GearNut]

A larger diameter piston would increase displacement only if you could find an appropriately sized cylinder to match it.
The skirt length of a piston would have to be shortened to be used with stroked flywheels. That or the use of a piston with a lower pin location. Changing a piston alone does not make a stroker engine. It is only but one component that must be carefully chosen or modified when doing a conversion.
The distance between the flywheel center line (crankshaft center) and the center line of the crank pin is what dictates the stroke length that the piston travels.