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Hello all - Recently purchased a 2011 KLR 650. I have searched many variations in different forums but I cannot get a definitive result or a straight answer with regard to this.
It has a coolant filter. The only reason I noticed this was when I purchased the bike it was seeping coolant (green stuff) very slowly on top of the starter.
Everything else was looking good so I bought it.
Upon closer inspection it appeared as though the filter housing was cracked, most likely due to vibration and heat fatigue). This bike has 22k klm on the odo by the way. When I called the local Kawasaki dealer (Campbelltown Sydney) he was highly sceptical of it's existence and yet here it is Part No. 16160-1359.
My questions are as follows:
Is this part of the cooling system necessary in Australia? It runs through the base of the carby (an old style Constant Depression design) which are known to freeze up at low temp. Fairly sure there are minimal times in Oz that this is required.
Should I bypass?
What are more experienced mbr's advice?

Thanks in advance :)
 

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It can be bypassed with no ill effects. I believe that the carb icing circuit is only on Australian models, which makes me think that the Japanese have some confusion WRT your proximity to the Antarctic.

I, and many other Merkuns and Canadanians, have ridden KLRs in subfreezing weather (wet and dry) and have had no problem with carb icing.

BTW, that pump cover makes for a very good start of a radiator bypass system.
 

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The "carburetor heat" scheme on Aussie KLR650s may indeed be, "An elegant solution to a non-existent problem." Yet, carburetor icing may occur in ambient temperatures well above freezing (thus sayeth Wikipedia).

Carburetor icing occurs as a function of temperature drop in the venturi and humid air. Not sure whether the temperature drop is mostly from atomization of fuel or from pressure drop. Regardless, carburetors may ice under certain atmospheric and operational conditions.

Water-heated intake manifolds are found on some marine conversions of automobile engines. As an English-as-a-second-language boathouse worker once said, referring to a manifold radiator connection, "That don't cold it, that hots it!" :)
 

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The proof is in the pudding IMO; none of our North American bikes have that system and I've yet to hear of a KLR icing up therefore I think it's pretty safe to say that it isn't needed and can be removed. .....arrrrgg, there I go agreeing with Tom again! LOL

Dave
 

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It can be bypassed with no ill effects. I believe that the carb icing circuit is only on Australian models, which makes me think that the Japanese have some confusion WRT your proximity to the Antarctic.

I, and many other Merkuns and Canadanians, have ridden KLRs in subfreezing weather (wet and dry) and have had no problem with carb icing.

BTW, that pump cover makes for a very good start of a radiator bypass system.
KLRMac,
It truly is a mystery to most of us why the Australian & New Zealand KLRs received the carb de-icing plumbing.
Northern Europe, Canada & Alaska would make more sense.

Yes the portion which goes to and from the carb can be readily eliminated.
But as Tom sort of suggested, instead of just capping, one can connect the thermostat outlet nipple to the water pump inlet nipple, while avoiding the exhaust header.
This will make a radiator by-pass re-circulating system to allow quicker engine warm-up. A larger hose would be Great.

Are you familiar with the Thermo-Bob 2?
Thermo-Bob 2 for KLR650

You could possibly purchase a warmer 90C thermostat over in Oz and have All of the exact same advantages. Quicker warm-up, improved fuel economy, consistent performance, cleaner engine oil.
 

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Actually Dave, there are some N. American Kawasaki road bikes which Do Use & Need carb heaters.
The VN1500 E series Vulcan Classic comes quickly to mind.

They are temp controlled by the big metal non-filter thingy after the carb, some how.
 

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The 1st gen Yamaha R6 (carb model) had the same system to all 4 carbs with a mini thermostat inline. On the California only model :laugh3: , the 49 state model did not have it. It was the only way it would pass the CARB emissions testing in Cali. Perhaps there was a similar issue with the Klr down under ?
 

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Actually Dave, there are some N. American Kawasaki road bikes which Do Use & Need carb heaters.
The VN1500 E series Vulcan Classic comes quickly to mind.

They are temp controlled by the big metal non-filter thingy after the carb, some how.
Sorry; when I said "bikes" in this context I was only referring to KLR's.

Cheers,
Dave
 

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I have read a couple of carb icing stories from riders who were caught in the Far North by early/wet storms.
A Bic lighter, Zippo or extended BBQ lighter held under the idle mixture screw area will thaw them out temporarily.

Oliver from BrokenToothProject apparently hasn't had to deal with the issue in his dead of winter rides or has learned how to deal with it.

In the winter time, we used to add a gasoline drier like "HEET" to our fuel, Isopropyl Alcohol I think. So does the use of Ethanol Alcohol reduce or eliminate the need for isopropyl alcohol in the winter?
 

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HEET dissipates moisture in fuel, functioning as fuel anti-freeze. Carb icing, as I understand it, relates to freezing moisture in intake air.

Ethanol alcohol? Consumed by the rider? Many effects claimed! :)

Carb icing comprises freezing of intake air moisture, a function of venturi temperature, not ambient temperature. Certainly, venturi temperature likely will be lower with low ambient temperature, but . . . carb icing at ambient temperatures above freezing are possible.

I think maybe an ATV or two exist with water-heated intake manifolds; not sure how "necessary" these accessories might be in our climate zone. Maybe worthwhile in more humid regions.
 

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HEET dissipates moisture in fuel,

I think maybe an ATV or two exist with water-heated intake manifolds; not sure how "necessary" these accessories might be in our climate zone. Maybe worthwhile in more humid regions.
I much prefer the Electric carb heaters of the newer atv models. Much easier to un-plug to clean, maintain or re-jet a carb.
 

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I suppose that I'd be inclined to repair what it came with.

Carburetor Icing is caused by the latent heat of vaporization absorbed by the fuel as it changes from a liquid to a vapor state in the carburetor. If enough heat is absorbed by the vaporizing fuel; sufficient heat can be removed from any moisture (humidity/H2O) in the air that the water vapor turns to liquid water and then to ice (solid water). FWIW it takes a LOT of heat to do this. Between a pound of water's Latent Heat of Vaporization (970 btu's), Fusion (144 btu's) and Sensible Heat (180 btu's +) it takes the removal of an awful LOT of Heat to get vaporized Water to change into Ice.

There are all sorts of variables involved in Carburetor Icing: 1.) The chemical makeup of the fuel produced by the oil refineries can dramatically affect what is called the Reid Vapor Pressure of the fuel, among many other characteristics. The makeup of the fuel can dramatically impact the rate at which the fuel evaporates (Reid Vapor Pressure) as well as it's latent heat of vaporization. It could well be that the rules (or lack of rules) in Oz regarding the fuel available at the pump, may be what prompted the Japanese (or the Oz Dealer Network) to specify a Carburetor Heater. Old refineries and/or low or little regulation of Evaporative Hydrocarbon Emissions can have this result at the gas pump. 2.) The humidity of the air. More water in the air can increase the amount of ice generated and thus the likelihood of sufficient ice being generated to cause problems. 3.) Atmospheric pressure. The lower the atmospheric pressure is, the lower the air pressure will be as it moves through the Carburetor. The lower the air pressure, the faster the fuel will evaporate, the more heat will be be absorbed by the evaporating fuel, the more heat can be absorbed by the moisture in the air and the more ice may result.

Water in the fuel can and will be a problem in other ways, long before it has any significant effect on Carburetor Icing.

For additional information on what the Latent Heats of Vaporization and Fusion are; for a start, please see: https://en.wikipedia.org/wiki/Latent_heat

For additional information of Reid Vapor Pressure, please see: https://en.wikipedia.org/wiki/Reid_vapor_pressure
.
 

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Discussion Starter #13
Thanks all for the replies. You have confirmed what I suspected. I will bypass the system and let you know if there are any remarkable results.
Additionally, yes I have heard of the Thermo Bob and the Doohickey mods and I am keen to perform both as soon as finances permit.
 

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KLRMac,
Just remember that your bike is all ready 2/3rds the way to a thermo-bobed system. Just change the hose.
Yes I figured as much thanks mate.
Still got me buggered as to why the need for a filter screen in that circuit though...:skeptical:
 

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Yes I figured as much thanks mate.
Still got me buggered as to why the need for a filter screen in that circuit though...:skeptical:
If & when you remove the carb & then remove the plastic upside-down 'T' with O-rings which the coolant passes up one side, then back down the other you may appreciate how easily paint flakes from inside the cooling passages of the engine could clog the 'T'.
 

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Googling the part #'s for images added some insight. Kawi # 49116-1081 is a thermostat.....the exact same part as the yami R6 used # 4SV-1240G-00-00. 16160-1359 by all appearance is an empty shell with the same fitting barb sizes as the thermostat. Some models use the thermostat, some have the clear body in place of the thermostat. So for some reason they want it pumping with the coolant full time and some they want thermostat control. I'm not smart enough to know why but I still think its related to whether they are working with icing issues or emissions testing compliance.
 

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flexiflyer,

The 16160-1359 is the filter body Before the heaters. The 49019-1068 Cleanable/Replaceable Coolant Filter slips inside of the body.

Take notice of a "gap" between a pair of hose clamps, possible part # 92170(A)-1863. This would be where the 'T' shaped carb heater 92005-1235 fitting is connected.

The 49116-1081 metal shelled thermostat body is placed After the carb heaters. And I can only suggest that its operational control is Ambient air temp or engine compartment air temp (fairings on R6), because of its downstream placement.
 

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Ahhh.......i should have perused the entire diagram :laugh3:

The R6 never had the filter portion which is the only "system" I have laid hands on. When I built the track bike i just removed and set it up like the 49 state model. Which interestingly (maybe) wasn't just capped off completely. One fitting was capped but a bypass line line ran between the other two. I rode that bike at some track days early spring / late fall where there was frost on the windscreen overnight. Never any apparent condensation or icing on the carbs those days as I looked the first few times just to see.

It's almost like they are treating the things like its a Farmall downdraft carb where the water just runs off the bowl hahaha.
 

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If the problem is just icing air due to pressure/temperature drop in the carburetor venturi, the simplest solution would be to dump some heat off the exhaust pipe into the air intake like on an old airplane I used to have.
 
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