Summer Planning for BBQ'd K-thighs

[tsbt]

Hey all,

This is a belabored subject with K's I've noticed but I wanted to ask specifically about the engine temp gauge. Now that it's getting warmer outside the heat is pumping out the engine sides sides more onto my legs. I've got good Sidi boots - will probably get a good pair of riding pants with better coverage from the heat very soon - in any event when the bike gets this hot my engine temp needle goes 80-90 percent on the dial before the fan goes on and brings it back to just above the mid-point. Is this normal? or should it come on earlier? Last summer I sat at the US border in 90 degree heat for 2 hours in holiday traffic, I'd swear I got heat stroke. I stripped down, actually turned the bike off and pushed it across the border it was so bad, heh. Anyway I'd love to hear other POVs

Also, I'm a bit of a purist, don't want to add any new covers or fixtures to block engine heat UNLESS I have to.
Cheers,
C

[mystic red]

in any event when the bike gets this hot my engine temp needle goes 80-90 percent on the dial before the fan goes on and brings it back to just above the mid-point. Is this normal?

That's normal.

[frankenduck]

Spread your knees out every once in a while.  (Seriously.)

[Jumpin Jimmy B]

K1100 hotness.

 I installed a manual fan switch. When the air temperature is around the 80's & I get stuck in traffic I'll keep an eye on the gauge. When it starts to indicate about 5/8
on the gauge I switch on the fan & leave it on till I am clear of the traffic and I have good air flow. Seems to work as the temp gauge will them fluctuate between 1/2 & 5/8 but get no hotter.

 Does not help the heat the engine throws back, but it doe help manage to keep the bike a little cooler or at least from operating in the high end of the temp zone.



 

[CrashBar]

I did the manual fan switch (ground out the sensor wire does the trick).  i toggle it on whenever i get in traffic on a hot day.

Not sure about covers or fixtures, but I love my johnny blanket

 http://www.motobrick.com/index.php/topic,1355.msg6216.html#msg6216

Took just a few minutes, and paint it black and no one even sees it.

I also don't hesitate to turn my engine off in traffic if I am going to be sittting.

[frankenduck]

Are you grounding the temp sensor wire? (Or the blue/yellow wire that the Motronic uses to trigger the fan relay?)

[tsbt]

Hafta trace that wire you mention FD, hopefully I can find it  :yes Could be my problem. I'll post some pics of the, what I considered, random yellow wire that runs from bars to battery. I'm not an expert in electrical by any stretch but I will give it lookseee.

c

[jsb]

It would be nice to figure out how to keep the sensor, and have the switch override the sensor. That way, it can do its job on its own, and I an override it when I see I'm getting into bad traffic or really hot conditions. It would have been great to have last summer on my commutes in the afternoon, when the temperature was getting up around 115.

[frankenduck]

For ABS I 4V bikes:  Have the switch ground the blue/yellow wire to the fan relay.




2V K bikes don't have a standalone fan relay.  The fan is triggered by the white temp relay which sends 12 to the fan via the Purple/Yellow wire.  If I were going to add a fan switch to a K75 I'd add a relay that feeds 12V to the fan and is triggered by grounding through the switch.

Terminal 85: Switch to ground
Terminal 86: Switched 12V (So the fan turns off when the bike is turned off)
Terminal 87: Power out to Purple/Yellow wire (fan power)
Terminal 30: 12V in

[jsb]

Frankenduck, would what you described above still enable the fan to come on automatically if the switch was set to off?

[frankenduck]

As long you tap into it the pruple/yellow wire and do not disconnnect it from the temp relay then the temp relay should still trigger it normally. 

DO NOT use a Scotch-Lok connector.  The fan draws a few amps so I'd make sure that things are well-connected.

[Inge K.]

Another metod which could be used on the 2V bikes is to tap into the violet/green wire between the heat managent relay and the temp sensor, and add a switch and resistor connected to ground.

AFAIK the sensor value should be ~220 ohms when at operating temp, based on this a resistor ~600 ohms should function, if the warning light is wanted as a reminder the resistor value should be ~300 ohms.

Haven`t tested this myself (live to close to the north pole), so it could be a bit trail and error with different resistors around these values.

Inge K.

[thebob]

Would adding an oil cooler help cool the 2V bikes. I notice the 1100 oil pump covers are tapped for oil coolers. Would they fit?

If the 1100 oil cooler would fit inside the radiator, I think this could be an almost invisible mod.

[wmax351]

Would adding an oil cooler help cool the 2V bikes. I notice the 1100 oil pump covers are tapped for oil coolers. Would they fit?

If the 1100 oil cooler would fit inside the radiator, I think this could be an almost invisible mod.

Don't see any reason. The bikes don't really have heat issues (besides comfort). And there is a large capacity of oil, in a highly finned sump. Radiator is over spec too: even the guys who turbo their bricks don't even come close to needing extra cooling (besides intercoolers for the turbo), despite having enormous power. Their street version of the K100 2v is rated to 180 hp at 15 pounds of boost. The only thing that needs changed (besides that turbo setup itself) is the fueling.

http://www.rbracing-rsr.com/bmwturbos.htm

BMW's remain perhaps the toughest motorcycle engines alive due to BMW's philosophy of overbuilding components then detuning the motors. Nikasil liners, Mahle pistons, dry automotive clutches and splendid cooling make them ideal turbo candidates. Probably the worst thing you could do would be to "build" the motor as they aren't set up to be bored / stroked etc. Changes in camshafts and cylinder head work will always benefit a turbo as the engine is nothing more than a glorified air pump and anything you can do to help it breathe will benefit a turbo motor.

With an oil cooler, you are looking at an extra failure point, and a completely catastrophic one at that. Hard to imagine anything worse than losing your oil, with a stream pointed directly at your front wheel, and in line with your rear wheel.

[CRASH]

With an oil cooler, you are looking at an extra failure point, and a completely catastrophic one at that. Hard to imagine anything worse than losing your oil, with a stream pointed directly at your front wheel, and in line with your rear wheel.

Please don't take offense, but I think that is a little over dramatic.  Most oil coolers are up front of the engine and behind/over the front wheel.  While there is always a slim chance, I would not fret much on this.  My K1200's oil cooler is over the front wheel, if it let go I would have oil on my tire and brakes and all over the back tire ultimately.  The chances are slim and I lose absolutely no sleep over it.  Can anyone here recall an instance of this occurring to themselves or anyone they know?  I had a oil line pop on a race track once.  Was placed right below the steering head and in front of the engine. Spewed oil all over the left side of my bike and leg (HOT oil at that) but never onto my front tire.

If someone is really worried about temps (and on these bikes, they just run hot - disconcerting to new K bike riders, but "they all do it") an oil cooler is a pretty solid way to over come  it.

[wmax351]

With an oil cooler, you are looking at an extra failure point, and a completely catastrophic one at that. Hard to imagine anything worse than losing your oil, with a stream pointed directly at your front wheel, and in line with your rear wheel.

Please don't take offense, but I think that is a little over dramatic.  Most oil coolers are up front of the engine and behind/over the front wheel.  While there is always a slim chance, I would not fret much on this.  My K1200's oil cooler is over the front wheel, if it let go I would have oil on my tire and brakes and all over the back tire ultimately.  The chances are slim and I lose absolutely no sleep over it.  Can anyone here recall an instance of this occurring to themselves or anyone they know?  I had a oil line pop on a race track once.  Was placed right below the steering head and in front of the engine. Spewed oil all over the left side of my bike and leg (HOT oil at that) but never onto my front tire.

If someone is really worried about temps (and on these bikes, they just run hot - disconcerting to new K bike riders, but "they all do it") an oil cooler is a pretty solid way to over come  it.

Just figuring in terms of DIY installation.

I don't think oil temps are an issue. Especially with modern synthetic oil, and our bikes using 15w-50.

Would be kinda cool to have a rear mounted radiator. Somewhat pointless, but cool. Could be slant mounted on the luggage rack.

[thebob]

Just figuring in terms of DIY installation.

I don't think oil temps are an issue. Especially with modern synthetic oil, and our bikes using 15w-50.

Would be kinda cool to have a rear mounted radiator. Somewhat pointless, but cool. Could be slant mounted on the luggage rack.

The oil temp itself isn't a problem, but the op was looking for a way to cool the engine so that it didn't fry his thighs.

Looking at the problem of removing heat, cooling the oil is the most efficient way, because the oil is in contact with more hot parts of the engine than the cooling system is.

Because of space limitations I don't think it is feasible to increase the flow of the water pump. Possibly an electric pump in one of the hoses?

BMW do fit oil coolers to the K engines so I propose using their parts because of reliability. I'd suggest mounting an oil cooler behind the battery with a fan blowing through it. In that location the warm air would not be directed over the riders legs. The extra oil capacity of the cooler would also help.

For the regular cooling system some "water wetter" should help.

The way I see the problem is that you need to somehow increase the surface area of the cooling system. I'd imagine that the original radiators are as large as the space can accommodate.

[wmax351]

Some of this also has to do with design specifications. These engines are built to run witb a 90 *C + water temp. The fuel is optimized for that.

The cooling systems are incredibly efficient. The fact that a stock cooling system can handle 200 horsepower, and cooling a turbo, is testament to that.


Counter-intuitively, increasing flow can decrease cooling efficiency. That is why removing the thermostat doesn't help. My Formula SAE team experimented with controlling temperature of a GSXR600 engine with an electric water pump and our ECU, rather than the thermostat. We had constant overheating problems, even running the pump constantly. Put the thermostat back in, and use the electric pump normally, and no significant problems (other than a failed pump, and a driver forgetting to turn it on  :eek2:).

In terms of doable modifications, the first one I can think of for slow speed, traffic temperature control would be to set a switch to reverse the fan. That way it blows out, instead of into the bike. Wouldn't work at speed, though.

Better ducting could be investigated.

Rear mounted radiators would be feasible. Also increases water capacity.



http://www.cumminspower.com/www/literature/applicationmanuals/t-030_p93-115.pdf

[thebob]

Counter-intuitively, increasing flow can decrease cooling efficiency. That is why removing the thermostat doesn't help. My Formula SAE team experimented with controlling temperature of a GSXR600 engine with an electric water pump and our ECU, rather than the thermostat. We had constant overheating problems, even running the pump constantly. Put the thermostat back in, and use the electric pump normally, and no significant problems (other than a failed pump, and a driver forgetting to turn it on  :eek2:).

That does make sense to me. The flow rate needs to match the surface area of the radiator otherwise coolant passes through without giving up it's heat and is returned to the engine at a higher temp than normal.