The missus had been complaining recently that her Breva 750 wasn't idling properly for the first few miles on her daily commute. I finally got around to checking it out over the weekend.
I started the bike up and it was having difficulty idling even with the fast idle lever set at the maximum. It was also backfiring through one of the throttle bodies intermittently. Hmm that sounds a little lean I thought to myself. What's going on here I wondered as I got the bike lift out and raised the Breva up to where I could take a closer look.
I removed the plugs and they looked ok but a bit elderly so I replaced them just to be safe. Next I removed the two balance screws and connected up my gauges. On firing up the bike I noticed that the right hand side had hardly any reading at all at idle on the gauges. That's odd I thought as I blipped the throttle a few times trying to keep the bike to running.
That's when I noticed that the top mounting bolt for the right hand inlet manifold was missing. I looked underneath at the lower bolt and it wound out by around 5mm. No wonder the bike wasn't idling. The only thing holding the manifold to the head was the pressure from the throttle bodies. I was surprised that the bike ran at all in this state. Next I went round to the left hand side and surprise surprise, Both bolts on that side were loose too. Now I know for a fact that these bolts have never been touched since the bike left the factory so I can't explain how this happened.
So I replaced the bolt, tightened everything up, checked the throttle body balance, reset the ECU and the bike settled down to a nice steady idle.
The moral of the story is that when the missus complains about something wrong with her bike don't put it off. There may actually be something wrong with it