crankshaft replacement

I plan on getting a new crankshaft for my gilera runner 50. i plan to get a rms racing crankshaft, since in my country the only options i have is a taiwanese standard crank and the rms racing full circle crank. i have a standard 50cc cylinder, recently rebuilt the piston, a malossi flip homologated exhaust, planning to get an air filter, a stiffer torque spring and stiffer clutch springs. my question is: should i really get a racing crankshaft for my mild 50cc setup? or should i go for the cheaper taiwanese crank? thanks in advance.

Re: crankshaft replacement

Dirty30 Dillon /

IF you're going to replace the crank, you might as well not skimp on it. In the event that you want to go with a bolt-on kit, you will know the crank will be strong enough to handle it.

On the other hand, if you are planning to eventually get a stroker crank/kit and internal rotor ignition, etc., I would go with the asian made crank just to get you by.

Re: crankshaft replacement

my main concern is that the crankshaft will increase the rpms and that the piston will get a hard time coping with the high rpms. i dont know if this is true or not but that's what i've been thinkng. plus my bike had a bogging problem and it had to do with a bent crank, mechaninc "fixed" my crank and replaced piston, carburetor apparently(which i dont think he did) and the problem was there still. he managed to fix the bogging problem and he didnt give me an exact answer as to which was the problem. point is: i think he replaced my cdi to an unredtricted one, because my bike achieves a max rpm count of 10-10.500 rpm. that's why i've been thinking that if i install a racing crank the rpms will increase more and the piston will fail. might be a wrong carburettor tune but i think its unlikely.

Re: crankshaft replacement

Dirty30 Dillon /

> jim jim Wrote:

> -------------------------------------------------------

> my main concern is that the crankshaft will increase the rpms and that

> the piston will get a hard time coping with the high rpms. i dont know

> if this is true or not but that's what i've been thinkng. plus my bike

> had a bogging problem and it had to do with a bent crank, mechaninc

> "fixed" my crank and replaced piston, carburetor apparently(which i dont

> think he did) and the problem was there still. he managed to fix the

> bogging problem and he didnt give me an exact answer as to which was the

> problem. point is: i think he replaced my cdi to an unredtricted one,

> because my bike achieves a max rpm count of 10-10.500 rpm. that's why

> i've been thinking that if i install a racing crank the rpms will

> increase more and the piston will fail. might be a wrong carburettor

> tune but i think its unlikely.

The racing crank will not increase anything in and of itself. It is just made of a better alloy, with better bearings. Changing a crank out would not be the catalyst in blowing up your engine. Bad tune, airleaks, and bad timing would all do that.

Re: crankshaft replacement

thank you! will probably go for the racing crank, since the difference is around 30€ and i will most likely install a cylinder kit later on. thanks!

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