In may, I installed a DynaS ignition, together with new DynaS coils and was amazed to notice a 15-20% better fuel economy.
For a few trips, I felt wonderful finally reaching 230km on a tank without having to switch to reserve.
Then I put in new tyres, checked the valve-clearance (didn't have to change any shims) and put in new rear-brake pads. After doing so, my range went back to pre-electronic ignition times — or even worse.
Warmed up and at idle, the engine revs about 300rpm less than it used to - which causes frequent stalling at traffic lights.
Initially, I assumed the fresh brake pads were dragging, which they might have. But now, when on the center-stand, the rear wheel runs freely and the disc stays cold after driving a bit without applying the rear brake.
A bit later, I noticed one of the 2 bolts of the exhaust bracket at cylinder 2 was missing. That easily could've influenced back pressure hence influenced engine efficiency. I put it a new bolt though and that didn't change anything.
Tyres are new and pressure checked.
Ignition and coils are new — when installed, the coils received proper voltage.
Chain and sprockets are from beginning previous season.
Carburator has been cleaned (ultra-sonic) and set 3 seasons ago. Spark plugs are quite black at the moment, might lean-up the mixture now but I can't imagine that running rich causes a 20% increase in fuel consumption... I didn't adjust any of the settings lately.
Any ideas where I can start looking for potential problems? This performance loss can't just 'happen' can it?
happy to provide more details if needed!
'78 GS1000
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