Scooterotica

right having blown another crank on way to brid this year, i'm now looking for a new crank what would you suggest running a rapido 200 classic soon too be rebored to a 225 with a bit of tuning hopfully?(mick abbey tuning would be good)and thinking of putting a reed valve on at same time .oh i,ll be using a 30mm delly and possibly a fresco .
cheers art

MEC EUR??

Or if you are flush then the MB alpha has been a revelation to me! silky smooth and super reliable at prolonged high RPM.

Indian GP200 webs with 110 Yam rod and Yam big end race bearing from MB.

arthur wrote:right having blown another crank on way to brid this year, i'm now looking for a new crank what would you suggest running a rapido 200 classic soon too be rebored to a 225 with a bit of tuning hopfully?(mick abbey tuning would be good)and thinking of putting a reed valve on at same time .oh i,ll be using a 30mm delly and possibly a fresco .
cheers art

If you are seriously thinking of putting a reed valve onto your 200 Classic as it is, it will probably be slower using the standard piston and porting.
If you keep it as a 200 at a 66mm bore and fit a suitable piston (a Yamaha IT would be my choice) with a boost port or two over the inlet with enlarged inlet and exhaust port timings you will end up with something similar to a TS200... but this now being re-bore friendly... The Yam IT piston is 30mm compression height that's 9mm shorter than standard, so a 60mm stroke crank with a Yam 115 rod is a quick fix for getting the deck height set, with a slight increase to 205cc.

I Found this http://cgi.ebay.co.uk/yamaha-43g-it200- ... 1c0db5686e on Ebay it claims to be an IT piston but it looks like a mono-shock MX piston, as the ring pegs look a little too close together. The pegs on an IT (wider spacing) allow a wider single boost port to be cut in over the inlet, without the ring peg and open end of the ring having to run in the port.

You could also do this on a 70mm bore, as there are a couple of Yamaha 70mm pistons, but I don't think there the same compression height, which are suitable for boost porting having windows as standard. But the area for the boost ports will be slightly reduced in relation to bore size as they cant be cut in as deep with the bore now being 2mm larger in diameter. But the potential BMEP is usually greater with a larger bore.

If you do use a Yam 66mm piston like the IT, be carefull when widening the exhaust port as the skirts are narrow and the piston is not off set like a standard one and the primary can be exposed to the enlarged exhaust port at or around TDC...

i think that you would find that BMEP will drop with an increase in bore size matey.............

Art, Mec-Eur/Tameni makes a good crankshaft for stock to mildly tuned engines at a very fair price. I've run one in my Rapido 225 Race for a few years and the last rebuild it was still 0.001 inches true and balanced.

http://jet200.com/catalog/product_info. ... ucts_id=95

why not yam rod the old crank for 70 pound. same rod as whats in an alpha and all the rest of the disco cranks

but if you are ok for dosh the alpha is a smooth crank