14/53T 520 Pitch Sprocket Conversion

The stock gearing of the MC22 consists of a 17 teeth front sprocket, 52 rear sprocket and a 428 pitch chain. The existing sprockets were far too worn to use again and after looking at alternatives a 520 pitch conversion seemed a viable choice with lots of sprocket options. I decided to go with a 14 tooth front sprocket paired with a 53 tooth rear and change it in future if it's too ridiculous, this combination provides quicker acceleration while sacrificing top speed. 

The front sprocket is a SUNSTAR 14 tooth paired with a METALGEAR 53 tooth rear sprocket and QX-RING 520SRX2 chain.

New 520 pitch 14 tooth sprocket on the left, Original 428 pitch 17 tooth sprocket on the right

Original 428 pitch 54 tooth sprocket on the left, New 520 pitch 53 sprocket on the right

Fairing Kit Completed

The last pieces of the fairings arrived and the bike could finally get a glimpse at being complete again with a new front cowl, windscreen and front fender. The front cowl is a late 90's endurance FRP cowl, made by SILHOUETTE JAPAN. Very rare to come by in good condition as they are discontinued and can only be found second hand at japanese auctions. An OEM windscreen is to go with the cowl and for the front fender I opted for a cheap FRP TYGA unit as the stock one didn't suit at all.

SILHOUETTE JAPAN front cowl

SILHOUETTE JAPAN front cowl and TYGA front fender fitted

OEM Windscreen

Replacement Engine

After having issues starting the bike and trouble shooting for about a week, it turns out the engine has really sad compression readings. Double checking the carbureter settings, valves clearances and camshaft positions wasn't a fun time, then I found the ignition leads were badly corroded and replaced those with a spare set (a positive in hindsight) but it was a leak down test that revealed there was more than 80% leakage through the intake valves, which suggests something along the lines of bent valves. Considering it was running (albiet roughly) a year ago I would put it down to my own error at some stage while doing the clearances and not prior damage from the crash. One thing that does come to mind was that the torque wrench used was 1/2 inch and exceeding it's accurate range for the low torque settings on the cam holders.

Head rebuilding for an MC22 engine is more complicated than larger motorcycle engines and fairly costly when compared to buying a second hand engine. Thankfully sourcing a second hand motor wasn't too difficult, picked it up one afternoon and had it in the frame within an hour. These motors are bulletproof and will happily run past the point where the odometer resets but they need a lot of care when touching internals, something that will definitely be kept in mind when it's time to do the valve clearances on this second motor.

Huge thanks to Riley Duddles for providing a second hand engine and Rob Fry for lending his time, knowledge and workshop for a leak down test on the original engine.