FZR250 vs FZR250R

Just when I thought it was time to reassemble the engine, the 2fiftycc forum advised otherwise.
And so I decided to pull out the conrods again and measure them up. It’s all the same, except the FZR250 rod is 2mm shorter and 3g lighter than the FZR250R rod. The extra length helps to rev all the way to 19,000rpm.
Because of this, I can’t mix the FZR250 conrods with FZR250R conrods so I decided it was time for a very brief guide to the differences between the FZR and the FZRR.

FZR250 (model code 2KR)

Built between 1986 and 1988, the FZR250 was made as a competitor to Honda’s high revving CBR250R MC19. These are small, lightweight and very nimble.
You can tell these apart from the later models by its twin headlamps, single front disc brake, thinner rear cowls and cube tail light.

The 2KR is powered by a 249cc 1HX engine producing ~45hp with a redline of 18,000rpm.

FZR250R (model code 3LN)

Built between 1989 and 1995, the FZR250R was the main competitor to the higher revving CBR250RR MC22. These are slightly wider, but are still light and nimble. You can tell these apart from the earlier models by its square headlamp enclosure (except the 3LN1), twin front disc brakes, wider cowls, twin tail lamps and their thick deltabox aluminium frame.

The 3LN is powered by a 249cc 1HX engine producing ~45hp with a redline of 19,000rpm, however later models are limited to 18,000rpm and are detuned a couple HP.
All 3LN models have EXUP exhaust valves to control backpressure.