agcstoat
Registered user
I popped (or nipped) up to Earl Shilton from sunny Wiltshire on Friday to have Geoff work his magic on my 2014 GSA LC. The weather was - how can I express this - utterly shit. But I digress...
The first thing Geoff did was run the motor for a few minutes and have a listen. He pretty much immediately identified a misfire (as evidenced by a very rough idle), and every minute or so there was a "pffft" from the left cylinder, which was diagnosed as a sticking exhaust valve, most likely owing to a build-up of deposits on the valve stem owing to too lean a mixture and the knock-on effect of a higher combustion temperature than is strictly ideal. I was understandably concerned, as this is something I'd read about both in these forums and elsewhere. Geoff assured me that sorting the fuelling out would help to alleviate this.
Anyway, Geoff stuck the bike on the dyne and did calibration runs while I stepped out for a hot sossidge'n'bacon bap and a gallon of coffee from the excellent bakery-cum-caff down the road. By the time I'd got back the print-out from the initial run was on display and he had reprogrammed the ECU with his firmware. The initial run illustrated perfectly what I had felt from riding the bike - there was a huge hole in the torque curve right where you're doing about 60-70 in top gear, which the bike had really struggled to pull through. The fuel-air ratio was also static throughout the rev range after about 1500 RPM, with the result that the knock sensor was retarding the ignition and causing the flat spot.
I stood in the booth while Geoff then carried out three more runs - a baseline, then two top gear roll-ons. It was fecking loud!
Following the last run, we compared the results:
Overall, I'm seriously impressed with the work that was done - in particular the expertise that Geoff has clearly developed with the Bosch-badged Denso ECUs
At the same time I'm appalled by BMW's shitty quality control, or at least an incredibly cynical approach to the product that screams "We sell so many of these things, we can afford to take the hit if a few engines blow up".
Overall, 10/10 for Hilltop Motorcycles; and 10/10 for the sausages too.
The first thing Geoff did was run the motor for a few minutes and have a listen. He pretty much immediately identified a misfire (as evidenced by a very rough idle), and every minute or so there was a "pffft" from the left cylinder, which was diagnosed as a sticking exhaust valve, most likely owing to a build-up of deposits on the valve stem owing to too lean a mixture and the knock-on effect of a higher combustion temperature than is strictly ideal. I was understandably concerned, as this is something I'd read about both in these forums and elsewhere. Geoff assured me that sorting the fuelling out would help to alleviate this.
Anyway, Geoff stuck the bike on the dyne and did calibration runs while I stepped out for a hot sossidge'n'bacon bap and a gallon of coffee from the excellent bakery-cum-caff down the road. By the time I'd got back the print-out from the initial run was on display and he had reprogrammed the ECU with his firmware. The initial run illustrated perfectly what I had felt from riding the bike - there was a huge hole in the torque curve right where you're doing about 60-70 in top gear, which the bike had really struggled to pull through. The fuel-air ratio was also static throughout the rev range after about 1500 RPM, with the result that the knock sensor was retarding the ignition and causing the flat spot.
I stood in the booth while Geoff then carried out three more runs - a baseline, then two top gear roll-ons. It was fecking loud!
Following the last run, we compared the results:
- Fuel-air ratio now varies throughout the rev range, but stays around 13:1 +/- 0.5 - the mixture is now correct at all points and the ECU is adjusting the ratio according to demand, as it should.
- Tickover is silky-smooth, with vibration significantly reduced. The farting noise didn't occur as often, and should go away with time. If not, it's BMW's problem to solve.
- Peak power is increased by approximately 20BHP, but with an overall increase of between 10-15BHP throughout the rev range.
- More critically, the torque curve is now virtually flat with no large peaks or troughs, and torque from 2k-5k RPM is now almost constant around 70 ft/lb whereas previously it was less than 30 at 2000 RPM, and was only hitting 60 ft/lb at around 4k RPM.
Overall, I'm seriously impressed with the work that was done - in particular the expertise that Geoff has clearly developed with the Bosch-badged Denso ECUs
At the same time I'm appalled by BMW's shitty quality control, or at least an incredibly cynical approach to the product that screams "We sell so many of these things, we can afford to take the hit if a few engines blow up".
Overall, 10/10 for Hilltop Motorcycles; and 10/10 for the sausages too.
