Hope I'm posting this in the right place...

A friend of mine has a K1, and very nice it is too, but it's a bl00dy hot bike to ride, in more ways than one.

The heat from the engine is furnace-like, even in cool weather, in the current weather, it's fearsome. So he's had this idea of adding an additional/supplementary radiator, somewhere around the water/oil pump area.

Any thoughts from the collective wisdom here?

There are several posts around the forum on dealing with heat issues a problem with almost all K's.

That said, these bikes do not actually run hot if all things are normal (fan operational, etc.)

The bikes by design transmit a great deal of radiator heat back through the area around the engine, under the fuel tank and most notably around the driver's feet, legs & thighs.
Adding an additional radiator if it were doable would probably not change the temps of the engine since it's already running as designed. I like to ride occasionally in shorts and boat shoes with no socks on short runs around town. I find it manageable in cold weather, but absolutely intolerable in the heat. (We live in Phoenix, AZ).

Your best bet, like the rest of us is to wear knee high socks under some quality boots with denim pants and (perhaps) some good quality over pants to help reflect the heat and distribute it more easily.

Some K owners , like myself have added some aftermarket heat shields on the sides above & just behind the engine. I have them and the results seem marginally better. I've never seen a K1 up close so I don't know if these would fit it.

Interesting heat shields, any details as to source??

My opinion only, but do not try an cool the engine by fitting an additional radiator. You will end up with more wear as the oil will take longer to warm, and may not get to full temperature causing water to emulsify in the oil. BMW knew what they were doing when they designed the bike, so you are better off trying to send the heat elsewhere by fitting some sort of shield as in the post above.

It's just a fact of life that internal combustion engines are sinfully in-efficient wasting something like 90% of the energy from the fuel out the exhaust pipe and across the radiator airflow in heat loss. All that heat has to go somewhere (Global warming????)
Some manufacturers do a better job of engineering the airflow away from the rider than others.

The heat shields show up occasionally on ebay. the last guy I saw there was asking $25 each for them, I offered him less but he wouldn't budge. I guess he did finally sell them to someone but they didn't move as quickly as I expected they would, besides, the right side one was slightly damaged at the bolt mounting hole.

If you manage to fit a pair, don't expect a miracle. As I said, the results are not easily quantifiable but they seem to help. (Kind of like a loud Zorst seems to go faster)?

The K1 is particularly hot. Anyone who thinks that any other K is hot would be surprised to find out how much hotter the K1 is for the rider.

The main cause of this is the bike's aerodynamics, the fairing (especially the front wheel fairing) is designed to re-direct the air stream around the outside and not through. In addition the rider has more protection from that air stream than any other K series.

The engine heat builds up inside the fairing and get pushed straight onto the rider's legs when the fan cuts in (which it does much more frequently than any other K I've owned). My mate rode my first K1 just after I'd collected it. It was a fine day and the bike was warm. He actually thought that the radiator or a hose had split when the fan kicked-in.

There are two things that can be done. BMW recognised the issue after the bike was launched, they offered a heat shield arrangement that fits inside the fairing behind the radiator ducts.





Parts 10, 11,12,13, & 14 here:



The parts are still available and not too pricey. Fitting does require a major strip down though.

The second thing is to make certain that the radiator ducting is correctly fitted. The main shroud is rarely the problem, it's the two side ducts that connect to the shroud. These are a push fit and need to be removed for some servicing processes. The result is that they are often not re-fitted properly and when the fan kicks-in the hot air isn't exhausted through the fairing side vents but comes back onto the rider's legs.

You'll know if the ducts are attached properly because even in winter, in towns or when travelling at low speeds, it will still be very hot if they are incorrectly fitted.

The ducts are fiddly to seat properly, I've found that the best way is to slip a hand inside the duct, feel for the edge of the radiator shroud to guide the neck into the main radiator shroud while clicking it home by pushing with the other hand.

With the heat baffles and the ducts fitted properly mine is a lot cooler than my first K1 (which didn't have the baffles), even in this weather. I rode my first K1 around Spain for three weeks in high summer back in the early nineties. It was very hot but I think that I didn't notice it much in the cities because I was so intent on not being taken out by the local drivers!

Although I agree with what is written above, my simplified version is this.  

Once the engine is at operating temperature, with all the fairings etc, fitted the engine will basically be a big hunk of constant heat.  The only way to reduce this heat or the effect of this heat, is to increase the airflow across the engine regardless of the outside temperature.  

In other words, ride like the clappers.

I have a 1992 k100rs which is basically a k1 with the k100rs fairing. I had issues with it running a little warm, usually towards the top of the heat gauge. I tried everything, flushing, reverse flushing, water wetter, different water to coolant ratios, etc. I ended up finding that it's not uncommon to acquire a radiator from the early K-series bikes (1983-84) which are 50% bigger than the later models. The later models have 2 rows and the older ones had 3 rows. I bought one, made the necessary modifications to make it fit (nothing big), and now the bike runs in the right range with no issues, and it cools down to the right temp real fast when the fan comes on. I think that'd be a better alternative to running another radiator somewhere. As long as you have a thermostat in the right range, the bike should run in the right heat range.

Other than that, as people have said, find ways to redirect air away from the rider. I can barely ride my k100 in shorts (every once in awhile I digress and don't wear protective pants) due to the heat, but it's manageable.

go near naked ...much cooler .....
I had to do something about it ...tank temperature measured at 53 deg c and it was not comfortable at all in around the thighs etc
now no problems at all

yes distracts from the looks .... but ...it works for me

Commuting home at the moment I find that my iner thighs are bright red from the heat behind the LT's fairing.

Many thanks folks for all your ideas and inputs.

It's entirely possible Rob, the K1 owner, will be here soon(ish) with his thoughts...

I've been toying with the idea to try to cut a couple of earlier (R100RT?) fairing front vents into a K100rs fairing.....then somehow duct the straight in front air back and out at the lower legs. Cutting the holes and molding the front grills in looks do able........not so sure about the ducting though.....not much room available.

I have also thought of cutting a round hole right in the center of the rs windscreen and installing one of those clear round plastic vent openings like I remember from early 70's aftermarket fairings.....(was it Lufmeister?)....but kind of shelved that one cause it would be just too dang hokey looking.
Regards, Ibj..

Go to the motobrick site and have a search for the jonny blanket idea as it seems to work although a bit ungainly but as for the heat I decided long ago to be very meticulous as to the correct placement of all the rubber components which cuts it down as much as possible and live with the rest.
I have a double layer of insulation under the tank and knee pads which prevent the hot/red thighs.

Not sure I understand the problem?

Just have a bike for any situation.



Ok. Not all mine, but 2 of them are. A warm day bike and a cold day bike.

rossko wrote:Not sure I understand the problem?

Just have a bike for any situation.



Ok. Not all mine, but 2 of them are. A warm day bike and a cold day bike.

Ah today I take the bike....Eeny meeny miney mo.....!!!!!

92KK K100LT 193214 wrote:

rossko wrote:Not sure I understand the problem?

Just have a bike for any situation.



Ok. Not all mine, but 2 of them are. A warm day bike and a cold day bike.

Ah today I take the bike....Eeny meeny miney mo.....!!!!!

Only Miney and Mo are mine. Mo now has a fairing.

After 17 years of ownership my white bike has just been named. Mo.
After 6 months of ownership 'sell the bastard' has just been named Miney.

Thanks Olaf. I never knew it was that simple.
Maybe if you were at the birth of my daughters they would not both be named Bruce.
/ponder.

How quickly we derail a perfectly good forum question. Sorry Keef

charlie99 wrote:go near naked ...much cooler .....
I had to do something about it ...tank temperature measured at 53 deg c    and it was not comfortable at all in around the thighs etc
now no problems at all

yes distracts from the looks .... but ...it works for me

Can you do that in Australia? If you did it in the UK then you would get arrested for indecent exposure!

So are Ks Bruces or Sheilas???

Its been discussed in here before, it was thought possible to add a lower radiator and halve the top radiator allow ing air across the top of the upper radiator. Keeping the thermostat and its bypass tubing intact will ensure the bike heats up as usual and then has plenty of radiator to discard the heat via the nornal process same size but now in two different locations on the bike, a shield on the oilpump and waterpumpassembly would ensure no extra strain is felt in there. It was suggested the top radiator be amended to channel the coolant through it then down to the new rad then through it and up to the normal access to the bike infront of the plenum chamber, maybe your mate will be the first to try

92KK K100LT 193214 wrote:So are Ks Bruces or Sheilas???

I am never going to throw a leg over something called Bruce so I have a cuppla Shielas in the garage.

Miney Shiela and Mo Shiela

Never met a shiela called Mo though????????????????????? Do you think she's straight????????

I agree with Rossko "ya gotta be flexible" a bike for every occasion....garage cleaning day wife came out and said "Um I think we have a problem" I said "your right the garage needs painting"

Why have you stored a lawnmower engine in a bicycle frame?

quite the collection...and a valid reason to swap one registration plate across a fleet of 2 wheelers...

"Why have you stored a lawnmower engine in a bicycle frame?"

Insert rolling, laughing emoticon here...

Yep I reckon it needs painting.

what is the UK equivalent to
"Sheila".....is it Doris, or Sharon or Tracey???
certainly as long as they can be unexpectedly troublesome a bike will always have a girly name...like hurricanes, cyclones etc...

Hey 2slow The power egg Beeza and the trumpet belong in the house mate, sure hope this helps