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I have an early 1984 EVO FXRS and I have replaced the gasket on it.I also have a oil cooler
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kinda like the picture. My question is when I prime my oil pump are there any additional steps to get the oil cooler primed too?
 

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And that big honker could cause problems... I personally would rather Not put anything, in the return Line [except the filter...which I don't even like].. The Biggest Problem Shovels, Evo's, Ironheads, have ... Is getting oil Out of Them... A constant Struggle, if High Performance is at stake...
 

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Try it... but do Not be adding oil... getting overfilled and Sumped is a very real Problem..
Exercise Caution.. Return oil is Critical...
 

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Correct... but could have very negative effects if it obstructs return... in any way!!!

No Harley I ever had required Oil Pressure... id did however Require the oil be returned... unimpeded!
I'll slink off now...
 

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Evo's and Shovels have been carrying oil coolers under the frame neck since they were new scooters, without issue. Lockhart used to be the go to name in coolers. A used Lockhart is worth more now than they cost new.

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Those drag bike guys don't like them because every time they break a motor, the cooler has to go in the trash, and they usually don't need them, seeing as they often have to heat the oil before making a run.

Past that, the OP's cooler is not really going to do much for him, its mostly a show piece. All that chrome is going to reflect the heat back into the oil. And with that style cooler, the oil isn't in the cooler long enough to drop very much heat.
 

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OK
Fair enough... that one is not a Lockhart...and I don't trust Chiwanese anything...especially chrome ones....
 

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The one in the photo is an old Harley unit. No idea who actually made them for Harley.

Came with the scooter.
 

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The one in the photo is an old Harley unit. No idea who actually made them for Harley.

Came with the scooter.
I meant the one the OP posted... I am Confident, that at least in the Shovelhead days Lockhart made the H-D coolers... I have one here with the H-D logo, and Lockhart on it.
Not on a bike... We don't need them here in Michigan... I leave them on sometimes for the O.E. "look", but have personally had Milky oil, from Not running a cover, and I refuse to run that Iffy, Thermostatically controlled Gizmo... YMMV
 

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1986 FXRSC #3/1250 Original Owner
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The bike was designed to run without any oil cooler. If riding under normal conditions and the bike is jetted and timed correctly it wont overheat. Only a few bikes ever came from the factory with an oil cooler, m-8’s are completely different so we are not talking about them. People started adding them because we ride them like we stole them on the street and some race them. Now if you live in the southwest were 100 plus degree temps is common an oil cooler may be beneficial when its that hot. The problem is if you run an oil cooler at say 50 degrees with no cover on it your oil is not going to reach operating temperature which promotes premature engine wear. Its just the reason water cooled engines have different temperature thermostats, temperature controlled electric fans, etc so they run at a pre determined temperature. I bet that the bikes that came with oil coolers had a section in the owner manual that told you to cover them at a certain temp.
Too cold is no better than too hot. I have ran my evo for 20 miles on a 60 degree day and dropped my oil and you could put your finger in it and it was only warm. This is also why you need to warm up you bike. Especially an evo. Not waming up an evo causes a lot of base gasket leaks.
 

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"Only a few bikes ever came from the factory with an oil cooler,"
literally thousands of TC's came with oil coolers. And they need them. Pans and Shovels with cast iron cylinders and aluminum heads expanding and contracting at different rates, benefited from oil coolers. 80" Evo's with better expansion and contraction didn't need them. I do run a Lockhart on my 113" Evo here in the south during the summer..Cover it when ambient temps are 60 and lower. Therm talked about Lockhart coolers being rare as hens teeth, covers for them are even harder to find. I wish had one, currently card board and zip ties is all I have. No leather shops around here either.
 

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Evo's and before cool the pistons through the piston skirt. TC's and M8's as well as some big Evo clones cool the pistons with oil jets. They just don't have enough skirt area to transfer much heat to the jug. And that puts lots of heat into the oil and it needs to be removed.

Now with the evo, that piston heat was from an engine burning low octane gas at 8.5: 1 compression with real moderate timing settings. As well as a reasonably rich jetting when the design was finalized. And it worked pretty well, much better than the Shovels iron jugs. But if you add more heat, by pushing the spark lead up, or adding 10.5:1 slugs and high lift cams, you build more heat, and the EVO fin design becomes thermally taxed. The EPA more or less stretched the cooling limits to the max with their HC and CO limitations. Natural laws of Thermodynamics help this by making the jug fins more efficient as the temps go up, but the rest of the motor suffers. And they were running 1980's dyno oil. The oil was in some ways better than now, but suffered from a lot of thermal brake down at high temps. So we got the oil cooler as a solution. And the posers saw oil coolers on the hot rod scooters, so they wanted them for their scooters too. Just like the drag pipes and shorty carbs.

Now we have oil pan cooling, then passive little coolers followed by big passive oil coolers with some water cooling mixed in on the full dressers. And its all marginal with perhaps the exception of the M8 wet heads.

Harley knows the oil cooling is marginal. They prepped the scooters for oil cooler fans, before there were oil coolers as original equipment. They went so far as to label a socket in the fuse panel as being for an oil cooler fan.

Past that, if you have a full flow oil cooler, you need to bypass or cover it in cold weather. As said above, to much cooling is as bad as too little. You also need to look at the oil recommendations for the weather you ride in. 20-50 is not the recommended freezing cold weather oil wt. It might surprise some of you to find out that 20-50 is also not the recommended weight for Evo's in the 80-100 degree weather range, straight 60wt was called for. And that riding in temps over 100 was not recommended. But dealers in the south had 70wt oil on the shelf back then, because people did ride with temps over 100.
 

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One Fallicy... I know from experience that more timing creates less heat... retarded timing creates Gobs of heat... Try it yerself..

Certainly if you feel you have too much heat... check timing, then go Richer jetting... I'm betting richer jets does More for cooling than an oil Cooler!!
 

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One Fallicy... I know from experience that more timing creates less heat... retarded timing creates Gobs of heat... Try it yerself..

Certainly if you feel you have too much heat... check timing, then go Richer jetting... I'm betting richer jets does More for cooling than an oil Cooler!!
Late or early spark both raise combustion temps. Late spark = loss of motor efficiency, early spark = detonation. Late spark is more often seen or noticed, because oems use it to lower HC emissions, in no small part as a result of the increased combustion chamber temps. And while we can manage spark with a fine tooth comb these days, that was not the case back when. To get reasonably optimal spark at 2500 rpm, with oem parts, the spark was over advance at 4500 rpm. Most people were just rotating the ign plate a mark or three.
 

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Detonation is not really felt... even by oil...mostly having effect on Piston dome and Ring lands..
But... Yes Lots of Concentrated Heat..
 
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