250-500cc WR thermostat bypass

Well done Private Duke. Your mod looks too good!
BTW, nice shot slipping up in the rockies.

point taken ladies, next time someone asks for help or input on these forums i`ll refrain from contributing anything at all.

Most call them a rose bud, some a cherry blossom. Depends on which old time welder you're talking to . Haven't seen one used since the mid 90's, but was mighty impressed when I did see it & used for a day. Incredibly quick large area heating without burning like a torch can do. Makes disassembling ancient cars from the rust belt area so much easier. Also great to form sheet steel. & I'm guessing taking out big dents in a pipe would also be fairly simple, if you pay attention & don't use too much air pressure.

I was raised by two teachers. My father had a doctorate in organic chemistry. I happen to like the technical discussions but then again if you ask me what time it is I'm likely to tell you how to build a watch factory.

BTW a system with a thermostat cools more efficiently than one without. I don't know the details of the WRs with the thermostat, mine is an 09 and doesn't have one. If removeng the thermostat solves an overheat problem it indicates a fault with the design. Possibly the bypass circuit needs to be more restrictive or there is a cavitation problem when the thermostat is closed. It would be nice to know because the engine could benifit from being tuned and running at a constant temp.

We just got through doing a similar mod on a brand new KTM 350, excepting instead of fittings, we use a hose kit that removes the thermostat. KTM's run even hotter than Husky's. The thermostat allows the engine to come up to operating temps quicker, but will impede flow. By allowing higher flow while racing, we are able to increase the cooling capacity of the system without adding larger radiators.

again, agreed, a t-stat totally has benefits for certain engines under certain conditions. but not as an "add-on" for a hard enduro bike with a large, very hi-performance engine with a relatively small cooling system, and, under almost all conditions.

once the coolant heats up its open and stays open anytime there is even a miniscule load- it then becomes a restriction, choke point, turbulance inducer, etc. under exterme load/slow speed conditions.

this/these engine/s when opperated at even 70% capacity will produce enough heat that this thermostat is completely uneeded at slow to medium speeds. t-stats are gneerally designed for cruising/low load/low ambient temp, and/or, quicker/controlled warm up.

this particular t-stat is an add-on for quick cold weather warm-ups before an east coast enduro and a few other reasons im gathering, even street use if so legal in certain areas. most all the hammer heads remove them if the going is gnarly and its above freezing. there's several companies overseas marketing hose kits for just this purpose.

if i rode easy flowing stuff in 40* temps or less all the time i could see a benefit with a well designed system with an expansion recovery tank added to complete the loop. but this machine's intent is gnarly, tight trail hammering with clutch slipping, heavy doses of throttle and more. i aint taddy or knighter, but, i am that cussing angry midget twisting this thing to the stops in the stix.

unless this cooling system was at least 3 times its current size, with an expanion tank to complete the loop and fans, this particular t-stat is more of a problem than a benefit in 99% of cases.

the kinds of t-stats we are seeing on these bikes are for keeping the heat IN the engine, not expelling it. hence my, and others here in this thread's, mods- which amount to removal of same and restoring laminar/max flow, as was originally intended, for extreme use.

why the hell didnt i just say that....and save myself a lot of typing! lol.

Don't get me wrong, I have an 09 without a thermostat and I intend to leave it that way. That said, I don't think it's off topic for someone to ask "why". I'm interested in this because for what ever reason Husky decided to add a thermo to an off road bike that didn't have a problem and in fact is about as bulletproof as they come. "Why"

i agree dougy. i did some asking around. i orrig thought it was for street legal bikes, made sense there. seems there were some squaks about slow warm up's on these and katooms before a cold race like in north/eastern conditions of sort...so the euro factories started adding them for faster warm up before the kill engine sign went up before the dead engine start. that was the most popular repsonse i got from my inquiries. i havent asked HVNA though...but yes, why is relevent IMHO. so are t-stat discussions and mods as they apply to these bikes fo sho. ok- porky's almost ready for some serious floggage tomorrow...braaaap! cant wait....pa-pang-pang-pang BRRAOOOP!

I agree with you. I thought the "themodynamics" (just kidding rajobigguy) theory added depth to the discussion and wasn't OT at all. I was waiting for more.
As a side note: I suspect that MR Duke would have welcomed it too.

yes, by all means.

but, it was getting so far into theory/opperation of said dynamics (of which im not qualified in or formally educated on- and props to those that are, no disrepsect intended ) that the intent of this topic/mod was getting burried. i was hoping it would remain simple and related to the different types of t-stat mods/bypasses/eliminations and coolants used by all of us, as it pertains to this vehicle type, and the results of same so as to serve as a referance for everyone should they wish to DIY. sorta like a jetting/pipe/etc. thread kinda sorta dealio.

garmin 405 data:
dist: 49.88 miles
elev: 3500-7000' (local mountains)
elev gained: 8000' (weak i know sorry)
ambient temp: 75*
-
total flogg fest. giant forest whoops (you know the ones!), tight stuff, fast stuff, got stuck on a couple boulders getting up some big stuff. had to smoke the clutch to get up this element. i was fragged. rode as hard as i could. fast (and slow) hard rocky rutted climbs, burning the clutch and on the gas way hard doing flying W's uphill over roots, rocks and im not sure what that was. i abused the bike like a rented mule and it proly thought i'd lost my mind. it carried me. i was wheezing from the thin air at the top. porky was just baaarroooop- gimme more old man!

checked the coolant after the ride upon getting home. other than some sweat around the over-flow hose (normal) it lost nothing. the pressure/expansion stayed so low it never lost an ounce. never pinged er nuttin. ran perfect, crisp and hard as a rock fully tapped up down and sideways (a lot lol) with giant pines flashing by us. and one good crash (too fast up a lipped ledge in the tight stuff, ended up in the trees. dont ask! but it looked cool). wow. its race ready. wish i was.

very special thanks to ZipTy Racing for the FX+ coolant, and, Earl's Performance. give 'em both a hand.

barrrooop!

i think u would have 2 restrict water flow were thermostat was & then your jetting would have 2 be precise & your altitude & temp fairly constant

I just did a thermostat removal yesterday. Bought the older model hoses from my local dealer. Left and right single hoses going from rads to head and the lower crossover hose. Some Engine Ice and my temp sensor from my Vapor and Bobs your mother's brother.

I would not recommend adding any water flow restriction. I would however recommend trying to maintain the maximum amount of flow which will aid to better cooling.

Just adding to this, I went the OEM route on the lower hose, roughly $20 for the 2010 hose from the dealer. For the top hoses, they are basically straight shot hoses from the head to each individual radiator. So, I opted for just getting 3 feet of hose from an autoparts store. I think 5/8" is the size, don't recall, I just matched with the fittings. Total cost, about $25. I might switch back to the thermostat for winter riding, but it's definitely not necessary for March-October here.

Thanks for idea. I just did this today. I ordered the 2010 lower hose and bought regular 5/8" heater hose. I don't have an overheating issue, but I didn't want the thermostat to fail at the wrong time.

Karma's a bitch.

Something in my cooling system, either the T-stat or the water pump, took a dump on my bike today. Motor was sounding funny so I pulled over, engine was hot, rads were cold, coolant coming out the overflow (from boiling in the motor). Damn! Definitely not getting any circulation, except for maybe in the little bypass hose.

So, looks like I am removing my T-stat. I'm just going to go with a hose elbow and a plug; what have you guys been using for plugs for the little hose?

I may try to open my housing up and take the guts out, worth a try!