TZR 250 Exhausts
I offer three types of exhaust spec for the original TZR 250, the outright peak hp is pretty much the same for all the exhausts, but where and how they make the power can be different.
Firstly there is the road ‘100 spec’, which performs similarly to the original pipes, peaking at around 9500rpm, but with a stronger feel to the midrange, and of course much less weight and a better sound. The road pipes really benefit from altering the powervalve controller to open the valves sooner, see my page on ypvs controller mods for more info.
Next we have the mid-race ‘955’ spec, which pushes the power roughly 500rpm higher with extended overrev. This gives a really wide powercurve and is great for road bikes for a little extra performance. They also work very well for race bikes that have a peaky tune, as it helps fill in the powercurve that can get a bit lumpy when used with revvy pipes (such as the Jolly Motos)
Finally we have the ‘890’ spec, which is a high revving race pipe, giving roughly 1000rpm more than standard exhausts (depending on the state of tune/set up etc..).
Below is a collection of dyno curves for the various TZR exhausts on a modestly tuned bike, for reference the white curve is from the earlier Jolly Moto type;
This is the 955 spec compared to the later Jolly Moto’s on a tuned bike, a typical example of a revvy tune running with revvy pipes giving a lumpy curve, and shows the 955 spec really smooths out the curve.