I was a bit surprised at the interest in the old Bully, so I'll bore you with more details. Frame and suspension is all stock and works well. The front wheel was originally a 19" with a nice TLS brake; I changed this for an 18" from a Honda CB250RS. It's a lot nicer around town with the smaller wheel yet still doesn't get twitchy at speed. Unfortunately the brake will have to be upgraded though - despite coming from a heavier bike it's just not up to it. The stock instruments were pretty bulky so I changed them for a single electric speedo in a homemade alloy bracket. The usual clip-ons and rearsets and a fibreglass Ducati front guard are also there. The original friction steering damper was swapped out for a hydraulic.
The engine is from a Mk8 Pursang 360 MXer and is at 86mm bore so is around 370cc. The porting is to Naitoh & Namura's formulas and I'm happy to say the engine did exactly what it was meant to do. The bottom end got some attention too, with alloy packers welded into the case halves to help guide the flow into the barrel. The crank halves had their inner faces ground and radiused, again to help flow into the transfers. There was a fair bit of material removed so it took some work to get it back into some sort of balance. Buls have always had a weirdly shaped exhaust passage in the barrel so this was reshaped using an insert or "tongue" attached to the exhaust flange. The pipe itself is homemade and version number 3. It's about as far as I'm game to go - there's more power to be had in the pipe but it's at the expense of piston temp, and big-bore two strokes are looking for an excuse to grab the piston at the best of times so I'll be happy with what I've got for now. The carb is a VM40 Mikuni bored to 42mm on a homemade stub and ignition is a YZ125 Yamaha CDI with a button rotor and a dual output Dynatek coil. Yes that's a K&N filter and it's utter fuking garbage. The head has had the chamber reshaped and retains the twin plugs. I also fitted a compression release - it's damn near impossible to kick over without it and it'll skid the rear wheel if you try to bump start it even in 4th gear. The decompressor makes it easy or at least possible to start it. Clutch is Barnett. There's a lightweight li-ion battery under the seat for lights and blinkers etc; the YZ ignition has no charging facility.
It's never seen a dyno so I don't know what it makes - 60ish maybe? Doesn't sound like much but remember it's 110kg, it certainly doesn't feel slow compared to my old GSXR. Just a lot louder and more fun.
