1150 GS back firing since fitting a Y piece

[Mr Otford]

Since replacing the cat with a Y piece I've noticed that there is a greater tendency for the bike to backfire. Any thoughts?

TIA

Richard

 

[Twotter]

You could do a search but I believe it's quite common and may be due to the joints not being quite sealed.

 

[Trippy]

Think thats par for the course.

 

[John Armstrong]

1 - Air leak somewhere.

2 - They all do that, the hard bit is doing it on demand

 

[ovenpaa]

1 - Air leak somewhere.

2 - They all do that, the hard bit is doing it on demand

It is difficult to do it on demand, I get best results from slightly off throttle after spirited riding.

 

[KMD]

I got exactly the same a few weeks ago when I replaced the cat with a Y piece. Did the Steptoe mod on the CCP and cured it instantly.

 

[PIGGLET]

Did you seal the joints? If not put a bead of silicone round the inner pipe before sliding them together and clamping up. Ordinary clear bathroom stuff will do the job

 

[Mr Otford]

I got exactly the same a few weeks ago when I replaced the cat with a Y piece. Did the Steptoe mod on the CCP and cured it instantly.

Steptoe mod? What's that then?

And no, I haven't sealed the joinst with anything more than Copper slip.

I find that closing the throttle after 'spirited' riding followed by a brief open/close on the throttle can produce a satisfying bang but a dissapointing absence of flame!

Richard

 

[Colban]

Go to the search button at the top of the page and type in "cat code plug",sit down with a beer and read.
All should become clear.Well at least,only slightly murky.

 

[pomm001]

Did you seal the joints? If not put a bead of silicone round the inner pipe before sliding them together and clamping up. Ordinary clear bathroom stuff will do the job

Dont do it !

Silicone will poisen your Lambda sensor and its non reversable !

remember the 'minute traces of silcone' in supermarket petrol recently that caused cars to break down !

google silicone and lambda sensors

Keep bathroom sealers for sealing bathrooms , not exhausts
Even the top grade automotive RTV's are only good for 225-250 short duration

 

[Shep]

Dont do it !

Silicone will poisen your Lambda sensor and its non reversable !

remember the 'minute traces of silcone' in supermarket petrol recently that caused cars to break down !

google silicone and lambda sensors

Keep bathroom sealers for sealing bathrooms , not exhausts
Even the top grade automotive RTV's are only good for 225-250 short duration

I thought the sensors were "upstream" of the joint concerned

Shep

 

[John Armstrong]

Keep bathroom sealers for sealing bathrooms , not exhausts
Even the top grade automotive RTV's are only good for 225-250 short duration

Wasn't the idea that the silicone is between the inner and outer pipes? In which case if it gets to 250 degrees C, what it's doing to something upstream is probably the last of your worries

 

[pomm001]

Wasn't the idea that the silicone is between the inner and outer pipes? In which case if it gets to 250 degrees C, what it's doing to something upstream is probably the last of your worries

The lambda sensor is down stream of where the 'Y' fits to the front 'pipes' and sits in the single tube of the 'Y' before going to the silencer

take a look at this web link to a Lambda manufacturer http://www.picotech.com/auto/lambda_sensor.html
a quote from the text ;
If somebody used the wrong kind of silicon sealer to seal up a leaky rocker box cover or manifold gasket, silicone can find its way into the engine and foul the sensor.

If you can apply RTV either to the male or female section of the pipes and then fit them into each other without pushing any silicone forward into the open pipe which could either migrate by burning, or vibration onto the sensor
then i guess you have nothing to worry about

 

[pomm001]

The lambda sensor is down stream of where the 'Y' fits to the front 'pipes' and sits in the single tube of the 'Y' before going to the silencer

take a look at this web link to a Lambda manufacturer http://www.picotech.com/auto/lambda_sensor.html
a quote from the text ;
If somebody used the wrong kind of silicon sealer to seal up a leaky rocker box cover or manifold gasket, silicone can find its way into the engine and foul the sensor.

If you can apply RTV either to the male or female section of the pipes and then fit them into each other without pushing any silicone forward into the open pipe which could either migrate by burning, or vibration onto the sensor
then i guess you have nothing to worry about

from the same site

A lambda sensor's normal life span is 30,000 to 50,000 miles. But the sensor may fail prematurely if it becomes clogged with carbon, or is contaminated by lead from leaded petrol or silicone from an antifreeze leak or from silicone sealer.

 

[John Armstrong]

The lambda sensor is down stream of where the 'Y' fits to the front 'pipes' and sits in the single tube of the 'Y' before going to the silencer

It was the previous post that mentioned this, not mine

I was talking about the sealant between the inner and outer parts of the pipe.

Good link btw put it on the "my bike's using 25% more fuel" thread

 

[pomm001]

It was the previous post that mentioned this, not mine

I was talking about the sealant between the inner and outer parts of the pipe.

Good link btw put it on the "my bike's using 25% more fuel" thread

John

it is a good link

it shows just how little we know about it and how easy it is to damage it , a squirt of WD40 will also kill it, so best take all reasonable precautions