We all know that intentional backfires, are big, clever and lots of fun, and those little pops on over run sounds wonderful but my FZR doesn't have the little pops :-( On over run, it will give one kill switch backfire type bang... Which hadn't bothered me until I rode it in the dark the other night, and realised that these things where lighting up the night sky behind me. How potentially damaging is this, as if it's just noise, I'm more than happy with it? --
Cooool.. keeps the cars away I'd bet... well, all except the ones with blue flashing lights on. Sounds like a hole in the exhaust maybe?
The exhaust all appears to be in good condition, so it hasn't rusted through, but I shall check for any leaks at joining points. I was presuming that the bike was just running a little rich, as the temp guage hasn't really left the cold section, though I have only been riding the bike since sunday, and it hasn't been very warm out... --
If it runs great from cold, and gets a little woolier once warm then it's running rich - though unless it's really way off it'll probably only be a bit iffy in a small part of the rev range. How does it run? How's it's fuel consumption? Bear in mind that old plugs and clogged filter and sloppy chain etc all exacerbate a fuelling problem as far as the ride goes. Without wishing to alarm ya, I've heard that burnt exhaust valves and bad clearances can cause this, as well as simple exhaust leaks. I have lots of pop-pops overunning down through 4k ish and I ain't worried. A real violent shut off at 6kish has twice made a big bang - that's in two years of use so I still ain't worried. And there *was* a plod following once when it did that, but that's a whole other story. For reference, my 7R is a little bit rich low down, but will still pull away from 30 in 5th on the flat. (And that's an engine that also does 60 in first).
Not usually dangerous except to the baffles - I've had the riveted end plate on a CX500 silencer blown off because of this. There may be another issue that needs looking at, though, if it's that loud.
How damaging do you think explosions in your exhaust could be? It may never cause a problem, or it may trash your can/valves/guides/engine. It's most likely caused by an air leak - when you shut the throttle the increased vacuum sucks air into the exhaust, igniting any unburnt mixture. Best to get it fixed imho.
I've owned an FZR600 Genesis and once, in a moment of stupidity, replaced an exhaust valve bucket without placing the shim properly in its recess (it had stuck to the bucket), so the shim ended up wedged at an angle. This didn't pop or bang, but idling was rougher than usual and there was a persistent 'ticking' that appeared to have no clear source.
