I have bought back the bike I had as a student, and have a collection of bits from which I'm trying to put together a good engine. Which bits to use? I have a spare early engine, but it had got damp and has a lot of corrosion damage inside. I acquired a late type Kangaru bottom end and am trying to sort out what to use. The barrels are bored for 375/64mm pistons from NLM. I also have a box of bits which might become a 250 again one day.
Comparing the cranks, the kanga crank weighs 3150g, and both its rods 372g. The pin side of the crankshaft cheeks are heavily cut away - appears factory original. The early type 350 crank weighs 3335g and has triangular cheeks. One rod weighs 306g, the other 288g. I don't want to use these rods as they have some corrosion damage. For interest, the 250 crank weighs 2835g with triangular cheeks, one rod 338g the other 336g.
The strada pistons weigh 254g complete, the 64mm pistons 276g each and the 250 pistons 236g. The aim is to have a reliable and well balanced engine: an obvious option is to use the kanga crank and rods, but I could use the 3/12 crank with a ball race on the drive side and roller bearing on the timing side- this is a slightly better crank.
I've put this up partly for interest and partly to see if anyone has any experience of mixing early cranks with later rods and/or 64mm pistons. I was interested to see how close the weights of the later type rods were for each pair, whereas the early ones were nearly 20g different. the 64mm pistons are heavier, but again, they both weigh the same. The pin is thicker walled on the 64mm piston and 8-10g heavier. Don't want my fingers buzzing unnecessarily!
engine balance: cranks, rods, pistons.
Re: engine balance: cranks, rods, pistons.
What an interesting position you find yourself in. I am not a mechanic and can't answer any of your questions but I do know that Ing. Lambertini is extremely highly regarded round these parts for getting it right first time.
That said, there's every chance he might have incorporated his own developments into his own earlier designs - why don't you ask him directly while you still can? I'm sure someone in Morini-cyberspace has his contact details, or try the factory.
If that fails, several Morinisti in many countries have rebuilt their motors for various purposes and will probably reply when they're not out riding them.
Good luck,
Dom
That said, there's every chance he might have incorporated his own developments into his own earlier designs - why don't you ask him directly while you still can? I'm sure someone in Morini-cyberspace has his contact details, or try the factory.
If that fails, several Morinisti in many countries have rebuilt their motors for various purposes and will probably reply when they're not out riding them.
Good luck,
Dom
MRC 3082½