Several days after buying the bike, the speedometer started giving incorrect readings in damp weather. However, the mileometer continued to record the distance. Therefore no repair necessary.
Also, the engine started lacking power
intermittently due to running on only one cylinder. Changing the spark plugs made no difference, and whacking the throttle open due to frustration, cleared the blockage in the carburettor main jet. It was trouble free after that.
A bit of metal from one of the camshaft bearing caps broke off and got caught between the crankshaft sprocket and timing chain, thus knocking out the valve timing. This resulted in one of the rockers being shattered and two bent valves. New cylinder head (second hand off a GPX250R) and hours of labour was required. Cost approximately £600.
This failure was due to my inexperience and not poor motorcycle manufacture.
Please note when fitting the rocker cover to these machines, make sure it is seated properly, and then carefully tighten up the four shoulder bolts lightly (10NM is all is needed).
After having this repair done, the timing chain started to rattle on idle.
Easy enough to cure. Remove the tensioner, reset it, install it on the crankcase and the release it (ping).
The engine sounded sweet after that.
Apart from this, nothing really went wrong with this bike. Only consumables (tyres, chains, pads etc) and a couple of wheel bearings were replaced.
This little baby ZZR was quite pokey (35BHP at 12500RPM) through the gears and would do 100mph. The engine had more mid range than top end.
The handling was impressive.
The action of the front brake was worrying in the wet. I thought it was not going to stop.
I use to thrash this engine hard, and it never complained.
The rear tyre use to wear too fast for my liking and at nearly a hundred quid a time I had to sell the bike and ended up with a granny machine (Yamaha T80 Townmate). However, the ZZR was good on fuel (60mpg urban)
I would recommend this bike, but if you are not the one for DIY mechanics, then get something basic. Doing the simple things such as changing plugs, balancing carbs etc is quite a task.