Hi guys,

after riding a twinkie for 5 years now, I believe it's time to go back to an EVO again...
Although i am not a technician, nor can i work on bikes myself, i miss the soul and the sound of the EVO carburated engine.

Could anyone explain me what made the late EVO engines different from the earlier ones? And when have they been introduced, was that 1995 or 1996?
Also I'd like to know if there's a difference, regarding reliability?
Are there any known engine-issues I should be aware of?

All your information will be very much appreciated.

Geert

 

I'm interested as well. I passed on a late 80s Heritage because I was concerned with the improvements made after that. I was told that one of them is that instead of a knurled spline it would use a key.

 

One important difference is the new evos are top breather, meaning the crank case oil pressure is vented through the tops of the heads (actually the oil breathes from the rocker boxes, to heads, out the air filter, to be burned up qith the air/fuel mixture - at least in theory).

The crank case vents on the older motors were not as good, and oil usage was higher.

The latest development for aftermarket evos is that they are both top AND bottom breathers. I just saw an S&S evo that had both banjo bolts in the heads AND a breather from the crank case vented out the side of the bike.

 

so instead of the oil mist going out the bottom to the ground it goes in your intake, get all the filter and coats the carb. emissions thing.

 

Yes in theory - Of course, there are a ton of top breather evo owners who complain about oil on the pants legs, motor etc, but many times corrective measures can be taken. Mine puked oil daily, but worked it down to a slow trickle.

 

No complaints about my bottom breather.

 

Same here! A favourite tuning shop liked to fit both top and bottom systems on his more highly tuned motors.

Later Evos from the mid-90s (not sure which year) have sturdier crankcases, but I stroked and tuned my early one with no ill effect. The earlier ones had several silly things that could go wrong and I reckon I had all of them, but replacment parts in all cases fixed the problem. So you are best to ignore most of the old 'problems', that keep getting repeated, unless you come across a very low mileage bike.

I suggest any bike from 87 on.

 

'95 was when the stronger crankcases were introduced. I had no problems with the cases of my '94, but when I had it remanufactured by the MoCo in '01, it came back with new cases with '95 suffix part numbers. Apparently, Harley upgrades the remanufactured motors to "late" specifications.

 

When the replacement for the twin cam engine has been around over 10 years no doubt people will have their "rose tinted spectacles" on again just like you, the same thing happened when the Evo replaced the Shovel

 

Late Evo motors are bullet-proof...unfortunately not idiot-proof ;-) but they are just excellent motors.....Carby'd TCs are OK too, not a lot of difference in the sound between the two....if your TC idles too smooth just fiddle with the idle mixture ;-)