Time to report:
I spent a couple of hours this afternoon removing the fuel tank, the fuel pump assembly, doing the mod and putting it all back together. Its easy enough but you need to exercise caution when drilling as the drill bit grabs and pulls itself in. Breaking through the bottom of the black housing with the drill into the bottom white chamber goes with a sudden pop/crack. I wont expand on the method as its already covered in the threads.
The test ride was a revelation. The bike now revs so crisply on and off throttle, midrange grunt for overtakes is effortless, coming back on throttle in 2nd mid-corner at slow speed doesn't jolt/lurch it just applies a smooth wave of torque. The bike now rides better than I can ever recall. I have spent years and also time/money trying to pin down the cause of what my bike was suffering from, it just felt "wrong" somehow but I couldn't sort it. It turns out it was either a weak fuel pump, a low flow rate, a part-blocked "hidden filter" inside the pump housing or a combination of all of them. As I had to remove the housing to drill it out I did the pump whilst apart anyway, its only about £50 with an external filter added.
To anybody who's Hex GS/GSA is a bit grumbly and coarse, feels asthmatic to ride or just feels a bit "wrong", other than the obvious stuff like new parts and a good service and balance, consider doing the fuel pump and hidden filter bypass mod I STRONGLY RECOMMEND IT !!!.
For Mistacat, I shall try to get out and do a set of GS911 Logs on Sunday if time allows, nothing else has changed on the bike since my last set except this pump/filter bypass so the results may reveal something. Having wrung its neck on the test ride the adaptations may well have altered things again after getting enough fuel supply with the mods done.
Lastly, a HUGE thank you to the OP, without sharing the knowledge on the forum I might never have solved this issue (having tried everything I could already.)
I spent a couple of hours this afternoon removing the fuel tank, the fuel pump assembly, doing the mod and putting it all back together. Its easy enough but you need to exercise caution when drilling as the drill bit grabs and pulls itself in. Breaking through the bottom of the black housing with the drill into the bottom white chamber goes with a sudden pop/crack. I wont expand on the method as its already covered in the threads.
The test ride was a revelation. The bike now revs so crisply on and off throttle, midrange grunt for overtakes is effortless, coming back on throttle in 2nd mid-corner at slow speed doesn't jolt/lurch it just applies a smooth wave of torque. The bike now rides better than I can ever recall. I have spent years and also time/money trying to pin down the cause of what my bike was suffering from, it just felt "wrong" somehow but I couldn't sort it. It turns out it was either a weak fuel pump, a low flow rate, a part-blocked "hidden filter" inside the pump housing or a combination of all of them. As I had to remove the housing to drill it out I did the pump whilst apart anyway, its only about £50 with an external filter added.
To anybody who's Hex GS/GSA is a bit grumbly and coarse, feels asthmatic to ride or just feels a bit "wrong", other than the obvious stuff like new parts and a good service and balance, consider doing the fuel pump and hidden filter bypass mod I STRONGLY RECOMMEND IT !!!.
For Mistacat, I shall try to get out and do a set of GS911 Logs on Sunday if time allows, nothing else has changed on the bike since my last set except this pump/filter bypass so the results may reveal something. Having wrung its neck on the test ride the adaptations may well have altered things again after getting enough fuel supply with the mods done.
Lastly, a HUGE thank you to the OP, without sharing the knowledge on the forum I might never have solved this issue (having tried everything I could already.)
