R1150GS Backfires and Y piece

[beemenfast]

I have joined the forum today as I need some info that will decide if I buy a two 2year old R1150 GS Adventure. The bke in question is fitted with a Y piece and uses the standard BMW end can. I went out for a test ride and was amazed how often it backfired on the over run, especially in the higher gears. Is this "normal" or is this bike missing some set up to correct the backfire?

Philip

 

[littleredrooster]

"They all do that, Sir"

Seriously, most GSs fitted with a Y-piece tend to backfire. Someone will be along in a moment to say 'Mine doesn't', but, in my experience it is the norm. Many theories abound, but to minimise it, you need to have a gas-tight seal on ALL of the joints. Any air ingress exacerbates the popping.

I'm sure that it's caused by the much-lessened back pressure in the exhaust when a Y-piece is fitted, allowing more oxygen to be present in the silencer.

 

[Paul Wakefield]

The Y piece/standard can combination seems to be particularly susceptible to this. On mine it used to happen after a period of high speed cruising and/or when rolling off the throttle quickly.

Careful when horses are around!

Paul

 

[cookie]

slowing with a trailing, but not quite completely closed throttle does it for me

 

[beakmeister]

Just fitted a Y piece and it now backfires, never did before, bit annoying as it makes me jump, and I've got ear plugs in

 

[Blue Sweeper]

Yup. "They all do that Sir"

Mine did, but when I fitted the Remus end can the backfire went away. Shame 'cos I enjoyed this effect.

 

[Fanum]

Bollix.

It's all down to shoddy workmanship...seal that puppy up properly and she won't backfire.

Leave a gap for the air to get in, and she will.

Simple.

 

[beakmeister]

Bollix.

It's all down to shoddy workmanship...seal that puppy up properly and she won't backfire.

Leave a gap for the air to get in, and she will.

Simple.

Used exhaust assembly paste on the two down pipes to form a good seal, but what about the can, does that need it also? cos it's not quite as "snug" a fit as the downpipes.

 

[Fanum]

Yep, all of it from front to back.

I'm able to replicate this by loosening the joints...I discovered it after fiting a wudo lowering kit and not giving the nuts enough of a twisting up

 

[jimbo]

Personally I like the backfire. character I say!

 

[MikeO]

Mine used to backfire terribly on the overrun, but has gradually stopped - I'm guessing the carbon build-up at the Y-piece/Silencer joint has probably made it a gas tight seal (I didn't use any jointing compound on assembly).

So, you chaps just need to do some mileage, apparently...

Mike

 

[beemenfast]

I'll go ahead and buy the bike as long as the dealer throws in a tin of exhaust jointing compund, to seal the deal! Pun is obviously intended.
Phil