What sort of Harley is that...?

So the PO was a Harley rider and I guess he believed that 'loud pipes saves lives'.
My bike is a 2013 and has the original muffler & it is loud. I'm working through the exhaust system, tightening up the connections, replacing the gaskets on the mid pipe. The cover piece had a stripped bolt which prevented the PO tightening up the clamps there.
It still pops on deceleration, so I haven't closed up all the leaks yet. But now I'm wondering if you can remove the db killers from the stock muffler ? Which would explain why it still sounds like I'm riding a Harley

The stock muffler shouldn't be obnoxiously loud, if it is it has probably been gutted in the mistaken belief that it was in some way restricting the engine's performance. Either that or the owner just wanted to be a noisy moron!

The fact it's backfiring on the over-run may well have nothing to do with air leaks in the exhaust. The problem is caused with the stock mapping by the Marelli system not chopping the fuel completely on a negative throttle. It keeps delivering the idle quantity of fuel at any rpm even if the TPS reading is 4.6. The faster the engine is spinning the harder it is pumping and as it slows the induction and exhaust harmonics will, at certain points, mean that rather than igniting the mixture every firing stroke the motor will eight, twelve and sixteen stroke firing only every second, third or whatever cycle. When it does fire the hot exhaust gasses exiting the exhaust valves ignites the uncombusted mixture from the previous cycles in the exhaust, hence the crash-bang-wallop on the over-run.

An 'Open' pipe also has a profoundly deleterious effect on VE at certain speeds and because of associated charge transition issues will, if running a closed loop map or poorly designed open loop one lead to hampered performance and lousy fuel consumption. While this is true to a degree with most engines it is particularly severe with the Guzzi 8V due to its cylinder head and combustion chamber design and weird cam timing.

If you like the stock pipe I'm sure someone less enamoured with it will sell you a take off from a bike that has had an aftermarket can added for not very much. If you are thinking of fitting an aftermarket pipe make sure it has a dB killer and keep it installed. Your bike will perform better and your wallet will appreciate the smaller fuel bills!

Pete

I was working down the list; stop the exhaust being so loud, i.e. Open. TPS set & TB balance & then get a Beetle map. Not wanting to instal it on top of an out of tune engine.

Anyone have a discarded stock muffler to pass along ?

I have three! Unfortunately the cost of getting it to you would be prohibitive. Last time I looked there were several on the Bay of Fleas. There might be one in the Mercato section too.

Pete

Best contact TRw1 on this forum. He's giving away his stock muffler.

[You must be registered and logged in to see this link.]

Pete & Beetle thanks for the help. Muffler being boxed & weighed tomorrow !