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[Leon Novello]

I know, scotty, but the oil always seems to flow faster and thinner when draining from a hot engine. It always seems to pour slower and thicker when refilling from a cool container. That makes two of us who are confused.

[NUTTY]

Hi Smudger
I got my CGT in may run it in properly noisy top end same as you
Had it serviced still the same
Then had comp valve springs and cams fitted power commander K@N filter and full motad stainless exhaust
Nice people at hitchcocks said its fine
Still noisy top end but you cant hear it any more with the new pipe
Think everyone is correct just the way they are mate
Now done 2000 miles no problems as yet

[Rattlebattle]

In my experience all oils become "thinner" (less viscous) when they get hot. A 50 grade when warm will be about the same as a 20 grade when cold. A 20 grade will be very "thin" when hot. The monograde 40 I use in my old Triumph pre-unit is thickish when cold but quite watery when hot. Hope that explains the issue.

[Rattlebattle]

I forgot to say that the engine on my Classic EFI is surprisingly quiet; I would expect this for a bike with hydraulic tappets, but then again an alloy engine would be noisier than a l/c one. Mine certainly gets more tappety as it heats up but it's not bad, certainly nowhere near as rattly as my pre-unit Triumph. It is very quiet when the engine is cold.

[Paul M H]

There is a very interesting artical on Wikipedia about hydraulic tappets detailing some problems cause affect benefits disadvantage advantages well worth a read if you have a spare few minuets.
https://en.wikipedia.org/wiki/Hydraulic_tappet

[Rattlebattle]

Yes, hydraulic tappets are not all good news. If you have a Harley and want to tune it much the first thing to do is install solid lifters. For gentle plodders like these REs though, the advantages probably outweight the disadvantages. Personally I quite like adjusting tappets, or in this case pushrod lengths. So for me, hydraulic tappets was not a clincher.

[Deanobats]

On my 2015 B5 Bullet pretty much all you can hear are the tappets. They seem to drown out anything else. I'm thinking of fitting a noisier exhaust just so I can listen to something else.

[ric]

Mine was measured up for a silencer a couple of days ago (I'm just after something a bit shorter)
It will definitely drown out all engine noise from my bike and probably yours as well if you're less than a mile away

[Thack]

Scotty writes: "Always thought 20/50 grade oil was thin when cold and got thicker as it heated up if so you would expect tappets to be noisy when cold and quiet when hot."



No, it doesn't work like that. I can't remember the two temperatures used for testing, but say they are 0C and 100C. A 20W-50 multigrade has the same viscosity a 20-grade oil would have at 0C, and the same viscosity a 50-grade oil would have at 100C.



HOWEVER, a 50-grade at 100C is MUCH thinner than a 20-grade at 0C, so in reality a 20W-50 multigrade still thins out as it gets hotter; it just doesn't thin out as much as a straight 20-grade would.

[Deanobats]

I seem to get more tappet noise when the engine is cold. I don't mind it, to me it just means you have hear the engine 'working', in a way it's rather poetic and beautiful.