Beat the Heat! or, how to cool down your K-Bike

By: Cary Stotland
September 1998

Hi, Y'All!

Got a hot K-Bike? Here's a cool tip to keep those summer days in line.

I finally got me an '85 K100RT back the end of April. I have Don Feferman from Corpus Christi to thank for deciding to sell it for a measly $3500, 16K miles, unmolested side bags, BMW tank bag, full-fairing bra, updated stereo (JVC) w/DIN connector for a helmet connection, and just a scratch or two! A true gem. OK, maybe I'm biased. He tossed in both a Clymer and a Haynes manual complete with maintenance entries. I was in love.

I picked the bike up in San Antonio from Alamo BMW who brokered the deal, drove home to Austin, spent two days checking it out thoroughly, then packed it up and me and a buddy drove straight out to Las Vegas! Did a 3000 mile round trip, two days there, stayed for four, then two days back. It was nothing short of way-cool. My friend has an '85 K100RS, and I'd been riding with him for a couple of years. I had a 1975 Kawasaki Z-1 that I had bought new, and even after 23 years and about 75K miles (It'd gone through 4 speedometers for one reason or another) I'd still hop on it and do 1000+ mile cruises with Eric (my Beemer lovin' friend). Only thing was that I didn't know what I was missing until riding with him, me having to stop every 90-100 miles for gas, tweaking the chain every 500 or so, can of chain lube in my hand, etc., whilst he'd be grinnin' at me in between his every-200-mile-or-so gas stops. It got depressing. So I sold the Kaw. Almost cried, but took the $1250 I got for it and shopped the I-net 'till I found Don's Beemer. Took me four days. Checked it out, fell in love, and the rest is now history. Except for the payments, that is! ;-)

But being here in Texas, it didn't take too awful long once getting back from Vegas for that K100 to commence to frying me. We've just had a rotten summer. Stinkin' hot. No place for a K-bike, right? I spent a great deal of time studying the problem, and after a couple of tries, came up with something that worked like magic. Pipe insulation. At Home Depot, (I don't own it, sell it, work there, et al ;-}) I got a couple of pieces of the GOOD stuff, the smooth, soft, squishy kind. One for 1+" diameter pipes (its about 3" in diameter) and one for 1/2" diameter pipes (about 1 1/2" diameter). They come both split with tape strips to wrap and seal or whole (uncut). The uncut versions are much cheaper, and work great. The foam itself is around a half-inch thick. Total cost for both 6' pieces is under $5. Get the insulation and a roll of 1" wide foam tape that's sticky on both sides. I'm not going to bug you with all the trial and error stuff, but the end result was marvelous. So here it is. I don't think it'll do any good for an RS, but you RT and LT guys listen up.

First target, the gas tank. If you look on the bottom of the tank, there should be some aluminum-coated foam insulation already in place. If not, check with your dealer to get a retrofit. Take a good look at the fuel return line. That's the one that connects on the front corner of the tank. It runs right through the hot-air stream going past the radiator. To help keep the gas cool, I slipped an 18" (ball-park. YMMV) piece of the 1/2" I.D. stuff over the fuel return line run from the tank back to the pressure regulator. In order to keep from tearing it and to get it properly aligned, I had to drain the coolant and remove the left side radiator hose. Well, time for a change anyway, right? You also have to pay close attention to keep the insulation from getting into the fan blades of the cooling fan.. Once it's correctly routed, put the radiator hose back on and it all stays in place. Be sure and spin the fan blade to make sure it's still clear. Believe it or not, this helps keep the gas tank much cooler. But there's more...

My main goal was to get the heat flow escaping from between the fairing and the engine under control. This seemed to be the biggest culprit in making my life miserable. With the tank back in place, by applying cut pieces of foam in judicious locations, I was able to accomplish this about 99.99%. The right side was the worst. It took several pieces, a couple around the air pick up tube and between the frame rail and tank, and a couple applied w/double-sided foam tape to the right fairing half itself. Also jammed a couple between the tank and the frame rails. I found that the correct approach was to try to guide as much of the airflow as possible through the vents on each side, and not let it out between the fairing and the engine.

If you reach your hand into the rear-most vent, you can feel (or NOT feel) all of the open space behind the vent. I sealed this area on both sides by sticking a 8-10" piece of the 1" foam with the double-sided foam tape to the fairing pieces just behind the vent. Stick it on parallel to the rear-most vent and close enough to where it will squish up to the edge of the vent. Bottom line is spend some time studying the situation, do some trial-and-error fabrication, and dam up every crack you can find where there is the possibility of air flow coming through the engine/fairing junction.

For you guys/gals with the 29" inseams, click here...For those of you with RT/LTs & long legs (I consume 6'4" of vertical bandwidth), those fairings can be mighty tight fits. I've got a Corbin saddle which makes it even worse, since it's a bit lower than stock, and cradles me forward, putting my knees squarely into the knee pads on the fairing. I took some of the large left-over pipe insulation (remember, the soft, squishy kind) and cut out two foot long pieces, slit them lengthwise, and mounted them with more double-sided foam tape to the knee pads AS knee pads. I stuck them on rolled out (cut edges pointing downward, center hump pointing upward...looked a little better when done) I also feathered the edges as much as possible. See if you can make them out in the picture. (URL to follow) I made 'em long enough so that I could mount a single piece to contact my knee at the normal position (feet on front pegs) AND lower down for when I put my feet on the back pegs, a la a back-rest-chair position. What a great deal! Not only more comfort, but those knee pads get warm, and the extra insulation helps the knees stay cool. Letting me place some of my weight on my knees helps those 600+ mile days roll on by.

The only downside is that the foam is a major bitch to cut clean. I tried a sharp razor knife, but my edges are kind of ragged, so it isn't the prettiest. Kudos to those who suggested electric and hot-blade knives. I've been looking EVERYWHERE to try and find the same kind of foam in sheets, so it won't curl and my cut a little better. If/when I do I'll let you know. In the meantime, I'm willing to suffer looks for comfort any day (form over function? Nah, not me! ;-})

The end result..

You guys in the Stiches close your eyes! Now, I can wear shorts while riding while it's 100+ without frying my legs! The only caveat is...wear socks! There's still a bit of heat on the left side coming off the pipes. Also, depending on cross winds, the air flow out the vents themselves can wrap back around some and get a little toasty. But the improvement was dramatic, and well worth the few bucks to do it. Now when I feel the heat, I can tuck my legs into the fairing and cool off. Quite a change! It took a couple of tries to get all the pieces cut just right, but there's plenty of foam to work with. Once you get 'em right, it just takes a couple of seconds to jam 'em back in when you remove the tank and fairing pieces for maintenance. The engine itself stays remarkably cool.

On a REALLY hot day, the tank will still eventually get hot, but it takes a great deal longer. For then, I got some 2" wide black foam tape that's about 1/8" thick and sticky on one side. You can see it on the side of the tank.

I'm probably going to add another aluminum-backed layer to the bottom of the tank someday soon, since I've got a left-over roll I used on the air-ducts in the attic, if I ever find the sucker someday! ;-)

That's it for now. Got a couple of other tricks I learned....More posts to come.

My favorite of all the closing remarks seems to have disappeared....

Carpe Beemum!
Seize the Beemer!

Cary Stotland
Austin Road Warrior