too much time and strange ideas are born.
what to do, when the racing engine explodes? you need a spare engine. not underpowered, its always good to have some horsepower.
the idea: i want to do a stroker engine, 1000ccm pistons, dohc 900 crankshaft with +6mm more stroke. this will give ~1100ccm.
but there are some problems to be sorted aut:
the 900 dohc crank has a "reverse" layout, ignition on the left side, alternator on the right. primary drive is a hivo chain, camchain ditto. 6mm more stroke will need shorter conrods or a 3mm thick base gasket. will the higher cylinder height be compatible with the length of the camchain? what about the chain tensioners? at the moment i do not know, what problems will occur furthermore, nor do i know, if i will have success finishing this project.
all i know is, that there are stroker engines with cb900 crankshafts outside running pretty well.
as for my 1000ccm engine i will use a F2 crankcase with the double bearing at the end of the transmission. cylhead will be from an early K modell. a webcam 315 will do the valve job.
my work started with investigations on the primary drive. it seems that the primary sprocket of an early gold wing will fit.
primary chain can be done by two prim chains of a cb 900 bol d´or.
tensioner: i hope i can take the rubber guide from the cb900, without the oil pressure activation, spring preloaded only.
what i have done so far:
i put the 900 crank into the sohc case to see that the crank does not spin free. there had been minor edges in the upper case that i grinded away. i believe a lightened crankshaft would have enough room to move, however.
next step was to machine the crankshaft to my plans. all i wanted, was to have the ignition on the right side (cranshaft seal from a bol d´or fits to the sohc case). i removed the crankshaft cone on the lathe and prepared the right end exactly as it is on a sohc crank. now a stock ignition from our 750 fits to the 900 crankshaft. drilling the hole for the stud was a bit tricky because of the existing obliquely oil feeding holes, but it worked. on the left side it will be possible to adapt an alternator, driven via belt or possibly directly mounted to the crankshaft.