Forum

[Chris Tindal]

Yes your right Mark, too distracted by kids, phones etc. Often been tempted to up the sprocket from 17t and I have an 18t on the shelf waiting to go on. Living in hilly Yorkshire though, most riding is up an steep incline so an extra tooth would mean more strain on the engine. Pity the sprocket isn't easier to change, then you could just do a quick swap before motorway journeys.

[Leon Novello]

As advised above.

[Leon Novello]

Hi Simon: These engines run cool, not hot. This is why there are a lot of problems
with emulsified oil/ mayonnaise. My 2000 Bullet`s oil temperature remains at 50/60 on long runs and stop/go heavy traffic in temperatures of over 32C in Queensland. I have even double-checked when I get home, by putting a thermometer down the oil spout into the oil, and it still reads 50c.

[Norm]

Leon, I have not come across them broken in that manner, all the ones we get down here just pull the top straight off, clean as a whistle. Don broke so many he could predict at least a hundred meters before it was going to happen. Proof of that is I was riding beside him one day and he shouted to me that he was about to break a piston and sure enough he rolled to a stop about a hundred meters later, kick it over and clackety clack.

[Thack]

Leon writes: "These engines run cool, not hot."



I'm a massive fan of actual data rather than assertions, and this is a great example. However, from what I've read these engines were notorious for overheating in one specific area: around the exhaust port and exhaust valve. Royce Creasey published a definitive article about this back in the '70s, including some engineering modifications to the cylinder head to reduce the problem.



Nevertheless, I think yours is a great post because it cuts through all the assertions people love to make and presents hard data. Clearly the oil temperature is - to all intents and purposes - never too high. I would just say that the oil circulation on these engines is poor (in terms of acting as a coolant) so it may not represent the peak temperatures at some of the working components.

[simon]

Err nonsense chaps, the oil temperature is crucial as other than air flow the oil is the most important coolant in an air cooled motor. The oil tank behind the engine means it doesn't get the same level of cooling as say a wet sump bike with a finned sump. The cylinder head and barrel is where the cooling is certainly an issue particularly in warmer climes. As the classic Brit twins attempted to extract more and more horses out of old designs for the American market they did things such as include oil coolers and of course oil in frame.

[Leon Novello]

Simon: You are agreeing that the oil tank being behind the engine, means it is not getting enough cooling air. So, in that position, it should be really hot; but it`s not, so if the tank WAS out in the breeze, the oil would be even cooler.
Your quote:

[simon]

Obviously not too hot all the time Leon but measure the temp after a sustained run at 65 mph. Moreover it's not simply a locational issue. The flow to the head is insufficient for high speeds to be maintained. My point was that these bikes weren't designed for motorway conditions. Look at any modern bike. 1. They are unit construction mean that the oil gets to be cooled in the gearbox, 2: they are almost without exception alloy. 3 if they aren't liquid cooled a large number particularly performance machines have oil coolers. My old Duke as an example has massive oil flow to the heads, nearly 5 litres of oil and a finned sump stuck out in a forward position.

[Leon Novello]

Simon: My Bullet is incapable of 65mph/ 104km. 90kmph / 55mph is its comfort zone. The oil in the reservoir, where the temperature probe sits through the drain plug, is seldom over 60C (which is the temperature of a dishwasher on wash cycle) after riding for hours.

[Revband]

As Thack said, actual data not assertions.