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This came to me from Edmund Rowe, one of the users on Glenn's KLR650.NET message board. (See the left-side link.) According to their discussion, this is a proven modification that pays off big for the small amount of time spent doing it. Thanks to "The Patman" for his original work, and to Edmund for providing a more accessible method.

* As always, all pictures are ABOVE their text *



This was not my original idea. On KLR650.net, a jet engine tech with the alias of The Patman thought this up. I just thought a radiator does its job regardless. He realized wisely that the air flow around the radiator was reducing its cooling efficiency.

The air gap between the left side radiator shroud and the radiator itself allows air to bypass it somewhat. My stock KLR normally runs in traffic with the temp gauge around the half way mark. Also I can feel heat on my left leg through my riding pants. After this mod it runs around the quarter mark while moving and gets up to about halfway WHILE STOPPED if the fan isn't on.

I’m not sure how well this would work on an aftermarket IMS tank since its rad cover is part of the tank.

The goal of this mod is to:

1) block the air gap between the radiator and the left side rad cover

2) Direct more air into the radiator itself.

The Patman made a sheet metal aluminum gap filler backed up by some foam rubber. I am not that tool-flexible or knowledgeable so I came up with this approach:


This is my A17 before installation. I’ve always had trouble lining up the top screw hole in the rad cover with the hole in the gas tank so I zip tie it in place. I found some small green zip ties in a multi-zip tie cannister at Wally World that are small enough to fit through the hole.

This view shows the gap between the radiator and the rad cover. As The Patman wisely noted, cool air wants to go through that gap instead of through the radiator.

Yes, I zip tie the rad cover in place by its tabs here, too.

Also note I have a Dual-Star radguard installed. From what I can tell the radguard was NOT necessary for this mod.

First step: after removing the side cover, cut three lengths of garden hose about 11” each. I made one slightly shorter than the others and cut an angle on two for an attempt to taper the top where the side cover will mash up against them.. The angles might not really be necessary.

Next, I cut a length of bicycle inner tube that slightly longer than the garden hose sections. You do NOT need one as long as shown here. This is the biggest size of bicycle tube I’ve found and had laying around for making ranger bands. FWIW it happened to be a Kenda brand I bought at Wally World about 7 years ago.

Insert the hoses into the inner tube. I planned on two that will rest against the radiator and the shorter third one will be against the rad cover.

Here I’m prepping 4 zip ties for attaching the gap filler. If you couldn’t tell already a lot of stuff on my KLR is zip tied on.

This is my gap filler installed. Note that the zip ties are pushed so the lock ends are not farther outboard than the gap filler. This would create the air gap again. I might have used 10 1/2” garden hose sections instead of 11” by the looks of it.

Use needle nosed pliers to pull the zip ties taut and cut off the extra free ends.

Note that the gap filler is aft of the radiator screen, not resting on it.

The reinstalled rad cover. The gap filler pushes it outboard about an inch or two. This helps scoop some air towards the radiator. Note that during installation the two tabs on the inside of the rad cover need to be resting on the forward side of the gap filler to ensure a snug, non-gap fit.

I also used two zip ties to secure the rad cover tabs to the Dual-Star radguard, but I don’t see why this couldn’t be attached to the radiator screen. You may also notice I used two green zip ties on the top screw hole this time.

The gap filler installed as seen from the front looking back. Now no sunlight is shining through. You can see the two black zip ties holding the radiator side cover to the Dual-Star radguard.

All done!

I was concerned for a while about radiator heat and the inner tube but so far it hasn’t been a problem. I noticed I can touch the radiator with my fingers after I shut down so I hope that means it isn’t hot enough to melt the rubber.

The Patman also noted that instead of air previously going in the side cover grill, now hot post-radiator air exits out the grill. If you have tank panniers blocking the grill it might affect the radiator cooling efficiency now while previously tank panniers helped it run cooler.

Many thanks to The Patman for his outstanding contribution to the KLR-650 community with this mod!