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KLR cooling question

10K views 29 replies 10 participants last post by  fradsham 
#1 ·
2011 KLR
How much difference do the leading edge slots, in the stock skid plate, make in cooling the bike?

I'm making an aluminum skid plate, and would like to know if I should put vent holes in the leading edge. ( Part directly behind the front wheel.)

The original one has several large slots.
 
#2 ·
Little to none, IMHO.

The liquid-cooled engine depends primarily upon its water pump and radiator airflow for cooling; airflow about the un-finned engine cases isn't a greatly significant factor, IMHO; I'd expect about the same heat exchange from the air space between an unvented bash plate and engine case.

Conjecture only; no test data; and . . . YMMV.

Wouldn't sweat the bash plate vents myself, but . . . your bike!
 
#6 ·
I was just making a comment that the Gen 2 never warms up. No need to cut vent holes in the skid plate. I don't have a Thermo-Bob on my 08. It has never gotten more than about a 1/3 way up on the temp gauge and I live in the Mojave desert!
 
#12 · (Edited)
Every once in awhile I let mine sit and idle in the driveway when it's hot, just to see if the fan still works.

I always thought those slots were there in my HT skid plate to use as access ports for either a flashlight or one of those little claw pickup tools to try to grab washers, nuts, etc. that I dropped into the skid plate and couldn't reach any other way.... I guess it's stupid to spend half an hour trying to extract a lost part when the skid plate will come off in 2-3 minutes, but it's good practice to keep your profanity skills polished.

Half the sounds I hear my engine making are probably loose parts rattling around in my skid plate. I consider it my spare fastener storage, a good assortment of hardware with a light coat of accumulated oil sludge to prevent corrosion.

Show us some pics of your skid plate when you get it done, larry31.
 
#13 ·
I consider it my spare fastener storage, a good assortment of hardware with a light coat of accumulated oil sludge to prevent corrosion.

Show us some pics of your skid plate when you get it done, larry31.

Good idea! I could bend up the rear portion of skid plate, and create a "pan" for hardware storage.

I'm almost done with it. Decided to finish it with bed liner from Home Depot.
Will take pix's and post when done.
 
#22 · (Edited)
I've done various testing in the dead of summer here in Phoenix and the skid plate affected water temp by 2 degrees - and I would surmise that it affected oil temps more. However, in the cooler months when it's 80F highs or cooler, I'm trying to get extra heat into the oil because I have monitored oil temps then, and with thermocouples installed in the oil, the method that worked best was blocking airflow to the engine block with an extended skidplate - photo below. That helped get oil temps up another 15 degrees closer to where you'd like them. Coolant temp stayed put at 195°F because I have a Thermo-Bob. My point is that yes, the airflow over the block does actually make a difference, and it's more to oil temps than coolant temps.

There's always a little confusion to the term 'running hotter'. That's relative. We don't want our bikes running 250°F when they can run 200°F, so "hotter is bad" and that what seems to get remembered. But we do want our bikes running 200°F instead of 150°F, so there, "hotter is better". 150°F is also better than 100°F, so in that case, 'hotter is better' as well.

The Thermo-Bob's goal is to hold coolant temps and oil temps in that 190-200F range all year. Its primary function is to help when it's 80F outside.. or 70F... or 60F... Heck, I live in Phoenix and 6 months of the year, it's 35° - 45°F each morning when I ride to work...

By the way, great workmanship on your home-made skidplate... very nice. Agreed with others that a low-profile drainplug from Eagle Mike is recommended... and usually, the water pump protection provided by some side shield coverage (like the aftermarket Moose plates) can really save the day.
 

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#23 ·
larry, Watt-Man (mechanical engineer that designed and sells the thermobob) had some testing data that supported the idea that no skid plate = cooler temperatures.

He also had testing data that played around with the left radiator shroud.

I'll go dig it up for you, however he recently migrated websites - as a consequence I'm not sure if I can find it.




Edit: I didn't realize there was a second page. Watt-Man himself seems to have beaten me to the punch. :)
 
#24 ·
Larry: Watt-Man (mechanical engineer that designed and sells the thermobob) had some testing data that supported the idea that no skid plate = cooler temperatures.

He also had testing data that played around with the left radiator shroud.

I'll go dig it up for you, however he recently migrated websites - as a consequence I'm not sure if I can find it.
My site is easier to find now - it's www.watt-man.com. If you go look under the "articles and information" tab I have some results of "how to improve cooling system margin"... there you'll see that the front fender and the left radiator shroud (at least on an A-model) are BIG players in cooling at speed. I tend to run a "chopped off" fender and no shroud in the summer here in Phoenix as it's worth nearly 25 degrees!

Although at first blush it doesn't help at 0 mph, it gives you more time before things get hot at low speed as you start out with cooler lower radiator exit water. This is one reason I like the manual fan switch idea - you can run the fan as soon as you 'see' a delay coming and maximize the time before temps get up there.

The KLR fan is robust, I've never seen anyone wear one out from overuse.
 
#29 · (Edited)
www.eastwood.com has everything the DIY'er needs to powdercoat at home. As far as the oven is concerned, an old used kitchen range will get you started. You only need 375-425 deg to "flow" your powder. You are only limited by the size of your oven as to how big your parts can be... Used to powdercoat for a living. As with most finishes, the quality is in the prep. BTW, most heavy equipment is powdercoated factory finished. if your powder is flaking off, you need to re-prep, or you are using the wrong powder.

Just my .02,

Maverik
 
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