My K75 has developed the habit of occasionally backfiring on decelaration in 3rd gear....am |I right in thinking its related to the TPS? If so, what's the cure?
Thanks.

Are you completely closing the throttle.  My k75 bikes both backfire if I don't close the throttle completely when coasting.  Both bikes have properly adjusted TPS and tight exhaust systems.

Possibly....I'll keep an eye on that, to see if I am shutting down the throttle completely.
Thanks for the reply!

Wow....I just became a Gold Member....that's a little bit "Austin Powers", no?!

BooG wrote:Wow....I just became a Gold Member....that's a little bit "Austin Powers", no?!

No, its John Cleese. Austin Powers comes next........

K75 may backfire as a result of a maladjusted TPS. It may also backfire because there is an air leak in the exhaust system, usually within the first 50cm (20") of the exhaust. That means either copper gaskets in the exhaust ports are leaking or the joint between the headers and muffler is leaking. Check these areas.

Incorrect mixture setting can also contribute to backfiring.
Regards Martin.

I found that I tended to backfire more after I turned 50....oh wait..that's thread drift.  Sorry

My wifes K75s always used to backfire more when the gasket between the headers and the muffler started to fail.

Woodie wrote:I found that I tended to backfire more after I turned 50....oh wait..that's thread drift.  Sorry

You're not the only one.  

My 75S has backfired for most of its life in similar circumstances.  The TPS appears fine and so does the mixture (Thanks Martin).  Quite possibly the exhaust to header gasket, as suggested but not going to pull the headers off just for that.  

I don't have a problem with it.  It sort of sounds kool, a bit like a hot cam 

AL-58 wrote:My wifes K75s always used to backfire more when the gasket between the headers and the muffler started to fail.

I think CF needs to move this thread to the humour section.

Just my thoughts, but I think if you've got backfiring, its a sign of unburnt fuel. The TPS not functioning or leaks in the header/exhaust system will be just contributing to igniting that fuel in the exhaust system as it escapes.
Quite a few here have disconnected their TPS to give a smoother engine braking experience. Not heard too many complaining of backfiring in these cases.
I'm thinking that on top of checking you have a tight exhaust system and your TPS is functioning correctly, that you also try advancing the ignition timing a smidge but within limits.
Another cause for unburnt fuel could be tight exhaust valves. My Old Girl (K100naked) used to go off like a rifle when backing off in 3rd and 2nd and usually as I was trying to quietly approach home. Exhaust valves were very tight. Backfiring disappeared as soon as that was put right. Best to check your valves anyway to avoid valve damage if this is the case.

Easy way to check for exhaust leaks is to stick the hose from a vacuum cleaner one of the ones that you can reverse to blow, up the exhaust and loosely seal it with a rag. Then spray the exhaust joints with a mixture of detergent and water. If you see bubbles ( soap bubbles not Michael Jacksons Chimp) you have a leak. Alternatively you can use a compressor, you could probably even use one of those cheap $10.00 12v tyre pumps.
Regards Martin