I just returned from a 1800 mile ride to New England...during last 100 miles I could hear a tapping sound from engine. Today I changed the oil...replaced with 10-40...started it up and still tapping.....I had changed the oil and filter before the trip. I did run it for 16 hours, with stops for gas and rest on the way back...any thoughts...

 

Strange. I have exactly the same problem, but my symptoms are worse. The tapping occurs when I go over 100k, the engine feels "lumpy' and I lose power. Effectively I'm running on the one cyclinder, which is doing the work of two. It rights itself if I drop my speed to say 50 - 60km/hr, accelerates fine, then the problem kicks in again - lots of tapping; drop off in power and a lumpy engine.

I've got a Boulevard C90 and bought the bik with just 3000k on the clock. I've had it for 2 years, and the problem has been recurring over that period of time. the dealer I bought it from is mystified, and reckons they can't reproduce the problem. I've had all sorts of speculative explanations:

1. dirty petrol - yeah right.
2. design fault on the air intake manifold
3. the Wellington wind (yep - they even blame it on a windy day)

I have the bike serviced regularly and I insist they change the plugs as part of a regular service. It's all fuine and dandy for a while following a service, but the problem kicks in a few 100K's after the service.

It's very annoying