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How to cool off your HOT running air and oil cooled V-Twin engine Part II

posted Jun 16, 2012, 10:15 AM by BikerChad Hensiak

Running Hot part II

Written by: Biker Chad


    In the last installment I discussed some of the high temp issues that all Harley riders face and the main factors that effect our engine running temps.  The first thing I talked about was the way moving air helps cool our engines.  There are not a lot of options to keep air moving over our engines except to keep the bike moving.  I often shut my bike down if I am caught at idle for a long time, like a train or traffic jam etc.  I do know a few companies that offer parade fans to mount on your bike.  I don’t put much merit into these fans, the help they may give is outweighed by the price of the purchase in my opinion.  If you pull a lot of parade duty I could almost justify it, but I think there are better things to do to cool down your bike.

    First, high quality synthetic engine oils can do wonders to lower your bike temperature.  You may have heard untrue stories of how synthetic oils can hurt your engine or make your clutch slip.  Hear are some of the ones I have heard. 

    I hear rumors about a louder ticking in an engine when synthetic oil is used.  This is supposedly due to some synthetic oils being slightly thinner than their fossil oil counter parts.  As long as I match the weight of the synthetic oil to the weight recommended by your bikes manufacturer, I have honestly never noticed this on any bike I have used synthetic oils in myself. 

    Next, I hear people talk about clutch slippage when using synthetic oil in their primary.  This can be true, but not because synthetics are bad.  It is due to most synthetic oils having a friction modifier in them, although this is good in your engine it may cause the clutch plates to slip sometimes.  As long as you make sure to use synthetic oil in the primary that does not contain friction modifiers (Amsoil does not use any friction modifiers in there oil), you will get no slip along with a cooler, happier running primary.

    As far as the transmission goes, good synthetic oil will allow a smoother, quieter shift, a cooler transmission temperature, and prolong the life of your transmission. 

    Another question I hear is, “will it void my warranty to use a synthetic oil.”  The answer is no, it will not void your warranty to use a synthetic oil (so long as it is the proper weight that is recommended by your bike manufacturer,) you cannot void your warranty.  If you don’t believe me Google search the Magnusson Moss Act.

    People have asked me if you have to use a special oil filter when you use synthetic oil.  The answer is no. The only difference in the filters is that a synthetic designed filter has a larger filtration surface.  This is due to synthetic oils lasting longer than fossil oils, so the filter has to last longer too.  A regular filter will work fine, but it may require you to change the regular filter before the synthetic oil needs to be changed.

    If cost is the barrier that keeps you from using synthetic oils consider this.  The higher cost of synthetic oil is way out weighed by the benefits of using it.  When things like the longevity of your engine being increased, the fact that synthetic oils last longer between changes (as long as the filter gets changed regularly,) and better fuel economy are entered into the equation, synthetic oils are much, much cheaper in the long run.  So I really have to say there is no reason not to use a quality, full synthetic oil.

    So what synthetic oil do I recommend?  Amsoil all the way, now remember I do not get paid to say this by Amsoil to recommend their products, I just believe that Amsoil is one of the very best oils out there.  I know for a fact that using Amsoil in my engine, primary, and transmission has lowered my engine’s internal temp. by about 15 degrees.  I have had friends tell me they dropped engine temps by almost 20 degrees using Amsoil!  That is a huge difference.

    Now that you know that synthetic oil will defiantly keep your engine, primary, and transmission cooler, while helping them last longer.  We can move on to discuss some other things to help cool off the Harley V-twin engine.

    Even when running great synthetic oil like Amsoil in your engine’s crankcase you can still go one step further to help your engine stay cool.  I always run, and recommend to every Harley owner that you run an oil cooler.  There are a lot of companies that offer oil coolers, so how do you pick one? 

    First, the more surface area you have on the oil cooler the more effective it will be at cooling the oil.  Six-row oil coolers help a lot, I recommend an eight-row cooler, ten-row oil coolers can be better still.  Keep in mind however, too many rows can drop oil pressure, this is why I recommend an eight-row cooler.  On built up engines with a high volume oil pump pressure drop from larger oil coolers should not be a factor.

    Second, good oil coolers need to mix the oil to keep it at a uniform temperature, and evenly disperse the oil in the cooler.  This is achieved by use of a “turbolator” in the oil cooler.  Make sure any oil cooler you get has a “turbolator” feature.

    Third, an oil cooler needs a thermostat.  It is possible to over-cool your oil.  Over-cooling can be as bad as being too hot, or worse.  An oil cooler thermostat works by only letting the oil flow into the cooler when it needs to be cooled, thus keeping the oil from over-cooling in colder weather.  So make sure you get a thermostat with any oil cooler you buy.

    There are several manufacturers out there that make oil coolers for Harley engines.  Jagg and Harley-Davidson are the two I like most.  Both are close in price, design and function.  I seem to install Harley’s oil cooler more often only because it comes with a thermostat in the kit.  With a Jagg cooler you need to purchase a thermostat separately, I have used both and recommend either manufacturer. 

    Oil coolers do work best when you are moving as it relies on moving air to cool it, just like your engine.  However when you are not moving, the added surface area of the cooler will still help to keep the oil temps down better than no cooler at all.  A smart guy would figure out how to incorporate a fan to blow air thru the oil cooler, much like a car’s radiator fan (maybe we just found a good use for the parade fan Harley sells!)  Either way, oil cooler technology has come a long way since the days when we used to take the transmission oil coolers from junked cars and mount them on bikes for home made coolers.

     Oil coolers are relatively easy to install for the at home mechanic, I do believe it is a job you can do yourself to save some money.  Just be sure to purchase a 7/16” Alan wrench before you do the install.

    Once your oil cooler is installed you should check the oil level after you fill and run the bike till it reaches normal operating temperature.  This will ensure you have not under filled the crankcase due the cooler being filled with oil. 

    Next month I will get into the A.F.R. (air to fuel ratio) and how we can correct it to cool off our engines and get more horsepower out of them at the same time.
    I install oil coolers all the time.  Most complete oil cooler kits run around $300 and with our shop rate at only $60 an hour, anyone can afford to have one installed on their bike.  EVERY Harley owner should have an oil cooler installed due to the high running temps of any air and oil cooled V-Twin engine it is vital to the performance and longevity of you motor. 
    Harley-Davidsons are not the only bikes that can benefit from having an oil cooler installed, any bike without a radiator needs an oil cooler and in many cases there are kits that can be installed that will re-locate the hard to reach oil filters with a spin on filter to greatly reduce the cost and time of changing your oil.  So no matter if you have a Honda, Susuki, Yamaha, Kawasaki or a Harley air cooled V-Twin cruiser in most cases I can make it run cooler.  Come and see me anytime or email or call me at 262-706-3278 to discuss options to cool off your ride.


Ride smart, Biker Chad