Noisy Exhaust

[Prosper Keating]

Thanks, gents! I will keep her as she is, stop being a lazy so-and-so and finish the twin. LOL!

Actually, I cruise her around 65mph. Sometimes she creeps up to about 70-73 mph all by herself. But she's happy at 65 mph. I remember some advice from an old hand many years ago about cruising the average British machine at around 2/3 of her claimed top speed. Mind you, a Vincent-HRD is not an average machine. But I used to cruise my BSAs and Triumphs according to this rule and less bits fell off.

Ah, Howard, but the mosquitos here are as big as pterodactyls...

 

[Howard]

I have a vague memory. That's it, just thought you might like to know that.

Sorry I've got a weird sense of humour too.

I have a vague memory that Phil Irving, in one of his books, said that most engines cruised happily at 4000 rpm. That gives Twin 85 mph ish and Comet 65 mph ish (I'm guessing the Comet). I think it was written a few years before my Fireblade was cruising at twice that rpm, but strangely I've often found that the cars I've had often have a sweetspot at 4000 rpm - could be my imagination.

The Vincent Rider's handbook says Shadow cruising speed 100 mph, Rap 85 mph, Comet 65 mph. I wonder what made the Shadow safer to cruise at 4,600 rpm ..... Bravado perhaps?

 

[Prosper Keating]

Well, I tried holding her down to 60-65 mph coming back up to the city yesterday. Quite vibratory.

With earplugs in, I didn't hear the clatter behind me as the flat bit of the rear number plate detached itself somewhere between Vendôme and Toury, complete with light and LED bulbs.

So I gave her her head on the N20, with a new-found disregard for the speed cameras, and she cruised with no noticeable vibes at around 75 mph.

The only hassle was all the helpful bikers pulling alongside and gesticulating towards my rear end...or, rather, the Comet's rear end.

Awful welding between plate and support, by the way. I've seen better work coming out of Pakistan. I suppose the lower nut and bolt behind the aftermarket reflector let go and the welding couldn't stand the shake, rattle and roll.

Just like my Triumph days...

PK

 

[Howard]

This thread seems to have changed a lot since the original noisy exhaust subject.

Can we change it to "what is the right cruising speed?" Is it down to engine revs, engine longevity, or rider comfort or ..........

 

[Tnecniv Edipar]

The 2/3's rule is wise advice. Even modern engines should not be cruised at more than 80% if longevity is desired from the engine.

 

[Prosper Keating]

OK, so what is the true top speed of a good, standard Comet and why do I find the Comet cruises smoothly at around 65 mph with the restrictive spiral-baffled silencer but around 10 mph faster with the Burgess-style noisy silencer?

Just to open another can of worms, I get more mpg/kpg with the noisy pot fitted. Plus I don't get cut up by cars or surprised by dull-eyed mothers shoving their sticky brats out in front of me in their wonky-wheeled pushchairs.

Let's face it: noisy silencers save lives, save fuel and allow faster travel, thereby cutting your road-time down, which in turn makes your journeys safer because you are on the road for less time than with repressive exhausts. And yet, none of our lobby groups will advance these arguments. Sack 'em, I say!

PK

 

[vibrac]

We have to get under 105db on the single and the twin racers so supertrap and a decible meter is the only way to go
BUT if you want choice put "snuff or not supertrapp" in the search engine

 

[Prosper Keating]

The dangers of reining in a Vincent-HRD...