When descending a steep hill using engine braking, sounds like a shotgun blast. Happened 3 times in 2 different outings. Less than 20 hrs on the 420. Anyone else experiencing this? I've owned fuel injected motorcycles and never had this occur when using engine braking.[img]i/expressions/face-icon-small-confused.gif[/img]

 

My 07 model has never done this and it has 800 miles on it.

 

Four or five times when it was very new. Very loud and very scary! Can't recall that it has done it since. Didn't do it at all on an all day ride last weekend.

No doubt Honda has them lean to meet emissions requirements. Dynojet has remaps. Haven't looked at them seriously yet myself.

 

If it is under warranty, take it in. Backfires can typically be caused in automobile engines by exhaust leaks and/or improper fuel-air mixtures. I figure it is probably the same for these engines.

100Proof

 

Mine did it once with only about two hours on the meter, also when using engine compression to slow while descending at a pretty good rate on a gravel road. I had just gunned it then quickly got off the throttle leaving a lot of momentum forcing the engine over, so it would seem there was just enough fuel vapor left in the cylinder to explode out-of-sync you might say.

If there were repeated or more frequent backfiring I might be worried about a problem, but the fact that you-all are reporting the same thing makes it seem to me that this is just a character trait of this engine, occurring infrequently when just the right conditions occur, and even then maybe only during break-in. But it would be nice to know with a little more certainty what it is exactly.