There has always been a lot of controversy around the effect a Race CDI has on a standard R model, while I had a friend and his ’91 R model visiting we thought we would try a test with our respective race boxes on a standard wiring loom.

The spec of his bike was:-  Jap aftermarket exhausts (one of the few types that we found that actually work), jetted to suit, with the first design of my modded experimental air boxes. With my bike these parts were producing around 48+rwhp (air corrected to SAE) with my programmable ignition.

Thus the scene was set, the 3xv-00 cdi I knew didn’t have enough advance, but also knew that the YPVS timing was about right.

DYNO Test Results Click Here

The red line - The standard 3XV-00 CDI

Good power till 8800rpm, with far more drive than standard, achieved mainly by experimental air boxes. Power drops off after 8800rpm as ignition retards off.

The Green line – The 3XV-80 box

From the start the CDI is over advancing, also the power valves don’t start opening up until around 7400rpm this is quite obviously too late. With the bike suffering all the way to at least 10,000rpm, also note NO extra advance.

The effect upon riding the bike however, is that the bike pulls harder and harder until 10,750rpm where the hp peaks, giving the rider the ILLUSION that the bike is now de-restricted. But it isn’t.

The Blue line – The mythical 3XV-71 box

The CDI is over advancing again but worse, not only that, the power valves don’t start opening up until just after 8500rpm when they open up quite rapidly. We see our first gains in power at 9100rpm then it disappears as the ignition starts to back off.

The Pink line – The TZ250 4DP-10 box

Much the same as the 71 box, too much advance early on but with everything happening later. The power valves are now opening far, far too late, almost killing the engine with power down to 8hp at one point. We have a power gain from 9750rpm-10,750rpm, and then the ignition backs off early again at 10,750rpm.

Conclusion

All these ‘RACE’ boxes are not giving the right ignition curve with good advance at the top end when plugged into the standard wiring loom, however I am sure this can be resolved when plugged into a race wiring loom.

The plain fact of the matter is, they were never designed to fit or work with a standard R model anyway, as you can see with the YPVS opening times. When you disconnect the variable air jet system the bike does not run quite as smoothly when the 00 box is fitted, so using a race box makes the situation worse.

This is why I took the programmable ignition route, as I want everything to work as designed apart from the ignition curve.

For best power with this set up on my bike (with programmable ignition and one other minor mod) click here