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[crusty buffer]

Thanks to everyone for all the valuable suggestions. Norm - rocker boxes OK. Mark - have been right through the primary side and clutch since the noise started, had a leaky seal behind the gearbox sprocket, so fitted sealed bearing kit and close ratio gears at the same time. Leon - have just been talking to Wayne at Hitchcocks, he thinks my semi-synthetic 15W50 may be just a bit too runny for my Bullet and has same suggestion as you, so have ordered some Silkolene 20W50. Why do I never ever think of the simple stuff first?
Will change oil at weekend and post result (once I have overcome new & exciting ignition switch malfunction).
Scaly, sound is bust on my monitor at work, but look forward to listening to your rattles when I get home tonight! Thanks again to everyone. Nigel

[Alan R]

Hi SCALY----------So it does !!..How odd...Can't say I've come across that one before....Can you pin-point it a bit more accurately with a Hearing Stick ??

[John M]

If the primary chain tensioner is slack it will make a "clack, clack, clack" sound and can sound like the bottom end knocking.

[Scalyback]

I tried a steffy scope, and the sound seemed to be from the area of the oil pumps.



We had a look inside, but worm gear all ok, very small play in pump spindle (forward/back)



We were stumped, but Chris, the mechanic thinks it could be the pump spindle jumping forwards, and tapping on the 'endstop'



Tornado's done the same all the time I have had it, so no apparent oil problems, just the odd tapping!

[Norm]

Nigel, just a point here I said check the rocker blocks and you replied the rocker boxes are ok, did you pull the rocker blocks apart and check the oilways in the rocker blocks are clear. First place you will see whitemetal collect

[Alan R]

Another place that might be worth considering is the exhaust cam and its' drive wheel area.........Due to the Enfield's ODD (IMHO that is--) drive train set-up, this is both driven by the crankshaft AND Back-loaded onto by the inlet valve spring etc, (as well as it's own valve spring), because the drive goes through the exhaust first THEN through the inlet second-----then an idler---then the distributor gear wheel..Other makes took a more pragmatic route with each cam being directly driven by the crankshaft ----and allied to a twin gear type pump in a sump directly below................Here's a BSA B40 for example >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

[Alan R]

------------- a nice, smooth linear set-up with a single, twin-cammed camshaft and each push-rod being the same length as well ( Cheaper production costs ---).........

[crusty buffer]

Congrats to Leon and to Wayne at Hitchcocks - warmed the bike up, drained the old oil and refilled with Silkolene 20W50. Warmed up again, switched off and put the bike on the side stand for 5 minutes, then started - no 15 second knock, smooth and quiet straight off, just like a Swiss watch (the noisy sort). Does actually seem to run more quietly generally, the rattles and clacks are much more muted! Another example of the life lesson I am unable to learn "The most complicated answer is not necessarily the right one". The offending lubricant was "Hi-Rev 15W50 semi-synthetic", I read the small print and it is made in Malaysia, possibly they are better at curries. Norm, sorry I was slow on the uptake with your original suggestion, couldn't see the connection between bottom end noises and the top of the engine, but of course, those tiny oilways in the rocker blocks are the most restricted part of the lubrication system and will trap any debris. Best wishes to all, Nigel

[Alan R]

Hello CRUSTY--------- glad you've got it sorted at last...I suspect the real "criminal" was not the "Malaysian Connection" at all but that reference almost at the end that says}---- Sem-Synthetic, allied to its' 15w/50 rating.....As laid down in the operators manual it's a straight 20w/50 for these machines PLUS an oil and filter change at every 1,000 to 1,500 miles ( The filters are cheap enough that you can do this.).......With regards to those rocker caps that NORM mentioned, as ALL the engine oil passes through these then an increase of oil hole diameter will help "up" the flow rate, which reduces oil pressure back strain on your oil pump quill drive...........Our hosts also do an pressure valve kit that dumps so much % back into the sump ...