I have been having all sorts of issues trying to get my 2005 Blade engine to run properly while keeping everything under the bonnet as it starts to lean out quickly once it hits 6500 - 7000rpm which I believe is my intake design with the secondary injectors:





This being the case I dummied up the factory trumpets and injector locations using some of the old air box and ran it on a dyno to rule out my intake design being the issue. I pulled all the way to redline but did the opposite, it ran super rich bottoming out at the max 10.2 that the dyno could display:





I figured it could be a faulty MAP sensor but I replaced it with one from another bike, I guess I could have two duds in a row. Has anyone come across this issue before with the sudden change in mixtures?


[Edited on 11/10/20 by DANMAN]

[Edited on 11/10/20 by DANMAN]

I assume you are using standard oe management, have you got a power commander or similar to map the fueling?

The changes are likely to be caused by the tuned lengths of the inlet tract being changed, giving resonances at differing rpm. Making the inlet longer will lower those resonance rpm's (approx 1000rpm per 4.5cm extra length) so will alter the fueling in both new and old rpm areas.

The extra rich running with oe inlet setup may have some bearing on your exhaust system, the exhaust system will be affected in the same way as the inlet by changes in collector diameter and runner length, as well as the silencer design. The original bike mapping is only good for a standard bike, ie just fitting a slip-on silencer will mess with the fueling quite a bit.

The plenum being only partially complete may also be affecting the fuelling on your old inlet, as it also has resonant frequencies when it's a closed fixed volume, when open there are none.

The map sensor should not be a problem so long as it reads correctly at full throttle, iirc most bike management systems only use map for fueling at low rpm, and use tps at higher rpm/engine loadings.

Dave