Poor starting / Running Rich

[jivebiker]

Had trouble starting last week, only got the thing to fire up by holding the throttle half open, then it sounded bloody awful for a few seconds as it was 8-stroking.

Checked the plugs yesterday, and they were well black, so much so that I am wondering if they were changed at the last service (3000 miles ago).

Looking into the barrel with a torch, I saw black soot covered piston crowns.

The plugs werent wet/oily so its not a weak spark, I think its just very rich running. My exhaust end caps always seem covered in soot, and when I did a gas analysis with a Gunson Gastester (shortly after I had Laser Inox Race fitted - with chip) it gave me 8%CO reading. Anyone know what is normal for Boxers.

I get about 45mpg, usually steady riding, lots of cruising at about 85mph.

Any ideas?

Cheers.

[oyster]

It would be worth checking the air in system for blockages. I have been going over my newly aquired R during the grot weather. The K&N filter had the remains of a colony of flying ants filling it. I mean hundreds of them. And yet the bike ran reasonably well.

[Jason M]

The soot and the black cylinder crowns sounds par for the course. I took Julains engine to pieces and it's cylinders were very sooty indeed but it had only done about 22k - he said it was running perfectly, just probably a bit rich - better that than too lean.

Jason

[jivebiker]

Oyster was right, it was the air intake.... because Hughenden M40 failed to change it at the 12k service! This discovered while having my clutch replaced at Sawbridgeworth. Having seen the state of the filter, it is testimony to the BMW fuel injection for keeping the bike running at all! Hughenden had also screwed up the throttle body balance, by doing it wrong. No wonder the bike felt so rough after the service. I wont be going back to Hughenden again.