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[nigelphoto]

Jefrs I love the phrase 'it bangeth and pops'. Another thread on here describes it as 'explosion from the exhaust' but that's probably the vindaloo! As well as bangeth my 2011 C5 also pharteth on the overrun but as a plug chop is spot on - nice brown biscuit colour - and my top pipe is a goldy colour, not blue then I assume the mixture's about right. However, last week I had to take the whole exhaust off to get at the bracket for the front silencer to get it welded, I noticed the port was pretty black with soot, although no actual caked-on deposit. The tailpipe has the same sooty carbon deposit which in the 'old days' would indicate a rich mixture, but nowadays more likely from the additives in modern petrol although having said that, I am running Esso Supreme Ron 97 which doesn't contain bio-ethanol unless you live in S.Wales or the South West.

[jefrs]

Plug colour is not so indicative with the ecu driven EFi, it is supposed to be lean burn. The iridium plug is pretty much fit and forget and repeatedly pulling the plug from an alloy head can lead to stripping the threads, don't get any grit down the hole. The steel plug can re-tap the head, oops. By rights one should replace the washer each time, they're not tight, finger tight nip plus 1/4 turn.



The new models don't have a bracket on the down pipe. The 50s just has the exhaust port and one bracket on the tail pipe, the original log has two brackets. Otoh it's about half the weight of the original.

Not many Esso here so running on Shell 99 or BP 98. Down pipe colour is coppery gold now, normal soot in tail pipe. Old trick is to hold a rag over exhaust to see what is coming out. Look at it and smell it. Water vapour is normal and part of the combustion products.



I couldn't get the 'asbestos-substitute cement' biscuit ring to seal the new down pipe, they crumbled away and there was nothing left of the last one when I removed the pipe. I assume it had been destroyed and shot out of the pipe. I had to use H's copper ring which is a little thicker, get two for 'ron. Silicone 'bathroom' sealant (clear) works better than exhaust gasket sealant goo. Silicone rubber will withstand a soldering iron, it works .

[Trev]

Bit late to this posting and new to the forum but .... I have a 2008 efi Enfield and have been running a shorter aftermarket silencer (from Feked bikes, made in UK) and a K&N air filter and, apart from blueing of the front pipe, no obvious issues. It starts and ticks over easily and definitely seems to pull better all the way through the rev range, so much so that I've fitted an 18 tooth front sprocket (tight fit) and pulls that pretty well, even two up. I did consider a Power Commander but as the bike is my cheap Winter back lane hack then cost seemed excessive and two years later I'm pleased I didn't part with the cash.

[jefrs]

The OEM indian exhaust did not blue. It is thicker walled and a little heavier than the "50s" free-flow which did blue until I added the PCV (whereupon it became coppery). Bluing is a sign of weak mix, which apart from discolouring won't hurt the exhaust pipe but may hurt the piston and combustion chamber.