What's a happy cruising speed for 16MS?

ajaygray · Post by **ajaygray** » Mon Oct 02, 2006 3:09 pm

Well at long last the post mortem has been carried out.
I sent the complete bottom end to Malcolm Saggers, for his inspection. (What an incredibly knowledgeable guy he is - a very nice chap).

On strip down the reason for the seizure turned out to be a blockage in the oilways of the big end itself. Sludge has accumulated on the outside surface of the channels which have 4 take off feeds to the bearing itself (if I understood what he was saying). It would seem that whoever went to the trouble of rebuilding the motor probably just checked the crank and big end for wear, as Malcolm is coonvinced that as the flywheels had no marks on them whatsoever, they had not been split since new.
So, the pump was fine after all!.

Hopefully, it will act as a warning for anyone who reads this to make a mental note for future reference, that what appears to be a good solid crank assembly doesn't always reveal all, unless it's fully inspected.

With any luck we should be back on the touring trail with the bike in the new year once all the rest of the work is done.

As a small aside, Malcolm was talking about his own bike that he was going to try to get to the Alternative rally on. This is an AMC single, with BSA Gold Star barrel and Velocette Cyl. Head - Blimey. Fair play to him, you've got to be really confident to even think about assembling that lot together as a tourer for serious use.

Anybody seen it? Keep the right way up everyone.

Gray

good-hifi · Post by **good-hifi** » Mon Oct 02, 2006 4:08 pm

I think the bike will tell you what it is happy doing. Some bikes will happily cruise at higher speeds than their siblings.

Experience and a bit of mechanical sympathy is the best way to determine the best cruising speed for a particular machine.

It all depends upon the condition of the bike and the rider..

. If it keeps running out of steam you just need to back off a wee bit so you have a safety margin of throttle in hand.

I'm all for riding the thing as it was meant to be ridden because I also believe you can run an engine too slow.

Closing the throttle momentarily will induce a vacuum and maybe a bit more oil into the cylinder but it will also shut of the air supply and the air/fuel mix into the cylinder is as much a coolant as air around it. So although it will increase the lubrication it will not really cool things down.

IMHO the best motorway behaviour is to change your speed at regular intervals, a wee bit faster, a wee bit slower. Not only does that exercise the bike better but it stops the rider going into a hypnotic stupor and maintains alertness levels.

CheersEdited by - good-hifi on 02 Oct 2006 4:20:52 PM

itma · Post by **itma** » Mon Oct 02, 2006 4:49 pm

you should have ahad a look at his modified Citroen Traction Avant if you thought the bike was impressive

itma · Post by **itma** » Mon Oct 02, 2006 4:50 pm

whoops againEdited by - itma on 02 Oct 2006 3:50:46 PM

crawsue · Post by **crawsue** » Mon Oct 02, 2006 7:59 pm

Having read all the previous stuff,and having had a similar experience, my local "guru" reckons that a big -end on a bike (especially a single)could last for ages ,even if it's badly worn,if it's just dodging around,but when you start to press them with sustained high speeds (55 mph !!!)the oil gets too hot,too thin and the bearing tolerances get too large for the "thin" oil to coat.Seems fairly plausible to me.Even the most exotic modern stuff have got oil coolers,and I notice from the current "Torque" Trumpet magazine that the modern Bonneville familly has been given a bigger oil cooler for the new model year--admittedly the engine size has increased as well---but it does point the finger at how effective oil is when it overheats.My heap (G5) has the infamous integrated oil tank,with a miniscule oil capacity--it's an accident waiting to happen!!!

56G80S · Post by **56G80S** » Mon Oct 02, 2006 8:11 pm

OOops, I used to run the G80S from Middlesbrough to home (then LOndon) at a steady 70 - 75 and only knocked out one big end in 70,000 miles and don't know the true milage of that before it went.

Somewhat sadly, in my youth, I had it replaced by Alpha with a "conversion"

No, not on the way to Damascus.

JDB

good-hifi · Post by **good-hifi** » Mon Oct 02, 2006 8:47 pm

quote: my local "guru" reckons that a big -end on a bike (especially a single)could last for ages ,even if it's badly worn,if it's just dodging around,but when you start to press them with sustained high speeds (55 mph !!!)the oil gets too hot,too thin and the bearing tolerances get too large for the "thin" oil to coat.Seems fairly plausible to me.Even the most exotic modern stuff have got oil coolers

Modern bikes rev three to four times as much as ours and that is the main reason they need oil coolers. If they ran at 3000-5000 revs they would not need such things.

Russian tractor oil, that's the answer.

Or of course the viscosity that the manufacturer recommends and therefore not a multigrade....

Modern oils of any viscosity far exceed the performance parameters of oils in the 1950s and I'm inclined to put some of the old wive's tales out of my mind and just enjoy the bike....

Cheers

Edited by - good-hifi on 02 Oct 2006 7:50:23 PM

TommoT · Post by **TommoT** » Tue Oct 03, 2006 9:39 am

quote:

....I'm inclined to put some of the old wive's tales out of my mind and just enjoy the bike....

by - good-hifi on 02 Oct 2006 7:50:23 PM

...what a splendid idea! Others have found that approach very rewarding!

Keep the rubber side down and the metal side up!

good-hifi · Post by **good-hifi** » Tue Oct 03, 2006 10:02 am

quote: ...what a splendid idea! Others have found that approach very rewarding!

Not sure if that is sarcasm or not as the internet is not a place where subtleness is easily recognised....

But to put my statement into perspective because I'm sure there are those that winced and raised eyebrows.

I have a 1958 Triumph TR3A, it is fully restored and I have owned it for some time. The TR3A was one of the first working mans cars which would exceed 100 MPH and this one still does. Of course only when it is legal but I tend to find an opportunity each time it goes out.

They were built to be driven and my car always sounds as fresh as a daisy and has never let me down. It is serviced regularly and cosseted but when it turns it's wheels it knows it is going to be showing many modern cars just what it is capable of.

I know many others with these cars which look just as good as mine and they seldom drive above 60 mph. Some of the drivers worry about their cars so much that, unless they are masochists, I am unable to see what enjoyment the car gives them. Apart from pointing out all the parts of anothers car that are not original!.

The cars that seldom exceed 60 MPH?. Half of them sound like wheezy old grannies and their performance matches their sound. The owners regale others with tales of the car having broken down, usually on a dangerous corner or the middle lane of the motorway, or overheated at the busiest traffic lights in town.

Why do they drive so slow?. Because they have been told many tales of weaknesses and engineering faults, usually by those that do not exceed 60 MPH, and are worried about taking the car over 2400 RPM!!!! (in overdrive)

I'm not advocating thrashing any machinery within an inch of it's life but this is a hobby and hobbies are meant to be enjoyed. Why have a hobby that is a worry?.

Cheers

TommoT · Post by **TommoT** » Tue Oct 03, 2006 10:44 pm

quote:
quote: ...what a splendid idea! Others have found that approach very rewarding!

Not sure if that is sarcasm or not as the internet is not a place where subtleness is easily recognised....

... no, not sarcasm, hopefully just a humorous attempt to draw your attention to the fact, that you're stating the obvious: ride and enjoy your bike, instead of worrying that it may break down any minute!

NB: subtleness = subtlety?