I bought an SR50 MT last week to get me around Perth while I'm here for a couple of months. Unfortunately after a couple of days it started showing its true character I'm very familiar with car engines but have never owned a 2-stroke so am a bit out of my depth and any help would be appreciated! It's a 2014 model and has done 12,000 km.
Basically it starts fine, idles fine and seems to run cleanly and make reasonable power with the throttle fully open. As I understand, it has had the inlet restriction removed but those in exhaust/CVT/elsewhere are still in place; it'll do 65kph on the flat quite happily.
However - at anything between idle and throttle wide open it doesn't run well at all, by which I mean it stutters and pops and generally doesn't sound happy.
Alongside this, with the exhaust removed, the side of the piston is a little scored which is a bit of a worry. There's clean oil on the surface of the piston so I think it's getting lubrication, but I guess it's been got hot or something in the past? Haven't had it apart further so no idea on state of rings/bore etc.
The last issue is that if left overnight and especially after a long run the previous day it's generally pretty smokey on start up which doesn't seem to clear until it's been ridden a hundred metres or so. I don't really understand why this might be, but I know very little about total loss lubrication systems or two strokes full stop. It's oil smoke rather than rich-mixture type smoke.
My first thought was to put a new piston and cylinder on it and see how it goes, but I can't seem to find anyone selling a suitable kit at all, in WA or elsewhere. I think the engine is shared with Piaggio so I was hoping parts would be available, but maybe not?