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I've now managed to lose not one but two of the brass sensor plugs from the rear exhaust pipe on my Falco in less than a year. One is unfortunate, two is just plain careless...

I thought something was amiss when the bike started popping and banging on the overrun, and also when cracking the throttle open again, on the way to Lake Vyrnwy on Saturday. At first I was thinking I'd got a bad batch of petrol, but when we pulled up in Wales all became apparent.

Has anybody else had this problem? Both times it's been the rear cylinder. Are there any precautions to take? Lock washers, Loctite, etc? I've even been toying with the idea of lockwiring the replacement I've ordered, racer stylee...

It certainly heated the shock reservoir up more than I would normally expect. As far as I can see, it's also a very strange thread pitch. It appears to be M10, but none of the bolts I had (M10 x 1.5, M10 x 1.25, M10 x 1.0) would screw in. Weird. Apart from that, lovely weather, lovely ride, lovely bike...

I've had one fall out and I've heard that others have too, so not uncommon, but unlucky.

I got a replacement from a local fastner shop in Surbiton, gone now unfortunately. The bloke there was great and identified the front plug as some sort of plumbing thread (I didn't tell him what it was at first to test him out).

He sold me a couple of slightly tapered grub screws and advised me to tighten them up carefully as the taper could split the boss, but given the thickness of the boss I think that's unlikely unless you're the gorilla that put the engine oil drain plugs in originally.

They worked beautifully and have been in place ever since, cost about 20p each IIRC.

So check out some heating/plumbing type shops or industrial fastener place with the front bolt.

HTH

Lockwire them in. Griff pointed out that mine weren't and that it's good practice to wire them to the headers.

TreeTops wrote:Lockwire them in. Griff pointed out that mine weren't and that it's good practice to wire them to the headers.

Yes, that's the real solution. But on the rear exhaust pipe it would require the manual dexterity of a triple-jointed bonsai dwarf...

Perhaps I can get Mark to do them when he's making me a new set of headers over the winter...