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Since my 2009 GSX-R1000 had a race system fitted it hunts on idle and the throttle response is vile. I’ve seen stuff about Yosh boxes or an ECU ‘flash’. Where do I start?

James Kennedy, Liverpool

Answered by James Holland, JHS Racing

What a flash can do is disable the top speed limiter and allow the engine to rev on further. It can also be used to change the opening rate of the secondary butterflies. To give an engine mid-range as well as peak power they might close slightly in the mid-range to give the engine more grunt. Trouble is, an ECU flash needs setup time with fresh engine maps for each gear at different rev points. But there is no need to go that far initially as a Power Commander should give you what you need for road use. It’s quick and easy to fit, and just as simple to remove when it’s time to sell the bike and you want to put it back to standard trim. Suzuki’s own Yosh Box is separate from the ECU, plugging into the output module for Suzuki diagnostics, and does allow some fuel mapping adjustment, but only in big blocks. That was OK when it was 16-bit electrics from the mid-90s to 2003, but then it went 32-bit, and 64-bit is imminent, so it’s not as refined as the Power Commander.

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