revtothelimit - motorbike forum

KungFooBob wrote: Sun Sep 03, 2023 7:46 pm I run waterless coolant in my Bullet.

MrLongbeard wrote: Mon Sep 04, 2023 2:12 pm Air cooled FTW

Trinity765 wrote: Mon Sep 04, 2023 11:01 am

Le_Fromage_Grande wrote: Mon Sep 04, 2023 9:44 am

Trinity765 wrote: Mon Sep 04, 2023 8:48 am The Speed Twin 1200 has a very hot engine and that's to be expected I guess. I was out all day yesterday at around 24c and the fan was on almost continuously. The worst thing is that my knees sit on the fins which is fine when I'm wearing thick motorcycle clothing, though they look a little melted, but when wearing jeans it burns. Reading comments on the Speed Twin forum a lot of people have this issue, burning knees and constant fan, and someone has said that their fan comes on 50% less using waterless coolant. The bike doesn't have an engine temperate gauge, just a warning light which has never come on and I don't believe that there is an issue as they all do it. It's more, I'm guessing, shorter people and where their knees sit.

My concern is that waterless coolant could corrode something that water doesn't and is it worth the faff of changing over. I would be wise to ask Triumph as the bike is still under warranty though I'm sure to get a "no" from them.

I wanted to know more about it as I've never heard of it.

I was going to say "Time to spread your legs" but decided it was too tasteless, but it does sound like you need to ride the bike with you knees away from the engine.

I do but it requires effort so when relaxing my knees fall on the fins.

I thinking about getting another Street Triple to be honest. It's becoming an itch that won't go away.

Count Steer wrote: Mon Sep 04, 2023 9:15 am . Some bike forums appear to conclude that the top end runs hotter with waterless coolant.

Mr. Dazzle wrote: Mon Sep 04, 2023 6:04 pm

Count Steer wrote: Mon Sep 04, 2023 9:15 am . Some bike forums appear to conclude that the top end runs hotter with waterless coolant.

Little bit cryptic maybe, but this should shed some light...

https://www.engineersedge.com/heat_tran ... _15915.htm



In essence this graph is showing how much heat various concentrations of Propylene Glycol (the main ingredient in waterless coolant) can absorb. I.e. how much energy it takes to heat these liquids up. Or to phrase it the other way around, if you've got a given amount of this liquid how much energy it can suck away from the stuff it's touching.

Note how water is the best (biggest number). Higher concentrations of PG get steadily 'worse' cause there's less water. Note how 100% PG goes further right though, all the others fall over at a lower temp cause the water starts boiling.

The reason to use some PG is to raise the boiling point, prevent corrosion and make the water "wetter"...break the surface tension so it "touches" the insides of the engine more and carries heat away better.

You're not gonna benefit significantly from a raised boiling point on an otherwise stock bike. Either the coolant will get too hot and break something else, nothing will change or the ECU will cry foul and kill it anyway. To really benefit you need an engine specifically set up for higher coolant temps.

If you did run 100% PG you can potentially reject more heat from the same sized radiator...hotter coolant, same sized rad, same air temp = chance to get more heat out of the rad. But if the system isn't designed for that you'll not see a benefit.

Yorick wrote: Mon Sep 04, 2023 6:40 pm I read many years ago that speedboat engines are the highest tuned as they have the biggest cooling system.

David wrote: Mon Sep 04, 2023 3:21 pm

MrLongbeard wrote: Mon Sep 04, 2023 2:12 pm Air cooled FTW

In the long run, all engines (even marine) are water cooled if operated within the confines of the atmosphere.