Are these engines reliable in terms of mileage? I know it's a performance based design but can one expect the engine to last for years?

 

Do your research. Scott or Kirby will hook you up with a much better performing 117 or 124 for similar investment.

 

They can be reliable YES. A lot more involved in making it reliable than just the parts though. Maintenance, tune and break in all come into play. If I was looking to go this route, i'd consider the S&S 124" as well as the 120R. 1 year warranty and very well engineered. I've installed in the past 2 months with great results from all of them.

 

IMO,their junk.you can build your into a 117" or 124" cheaper,built to your exact specs and have better reliability/dependability.

 

An S&S 124" is a better route.
The 120R is soft power off the bottom, which is more akin to a Dyna, or Softail build, but then again when the low torque is MIA, you are still fanning the shift lever on occasions, making the rider/owner wishing he had more low power.
A 124" much stronger crankshaft, larger cubes, roller rockers, higher quality lifters, etc.
Built 9, 124"s since just before Christmas, 1 is leaving again today.
Power on tap most anywhere in the rpm band.
Scott

 

I've had mine since 2013 and put about 23,000 miles on it. The month after it was broke in me and the wife took a 6800 three week road trip, with no issues.

Since then I've had a lifter fail that took out my cam/oil pump and cam plate. I replaced all of that with Tman cams and push rods and S&S lifters and roller rockers.

Plan to spend money on it if you install one and put any amount of miles on it!

 

Can't say that is an odd scenario, as we've witnessed similar issues as well here also.
S&S offers a very rugged replacement crank for them, for a reason.
Scott

 

S&S 124" upgrade using your stock cases or complete crate. As said, these builders can hook you up with a superior S&S platform that will give you plenty of HP and thousands of trouble free miles...win/win...

 

Not too many positive responses on the engine in question. Sounds like the S&S 124 engine is more dependable.

 

The engine section doesn't get a lot of views, I rarely look anywhere except the touring section but your Thread caught my eye. You might get more responses from owners in the respective section of your bike model(touring, softail, dyna).

What model do you own? I suspected touring when you mentioned mileage.

Either way you'll get a lot of mixed reviews from owners/ non-owners and builders, very few of us owners that have a good amount of miles on the 120R will tell you don't buy it if your looking for reliable.

If you can't do any of your own repairs I would stay away from the big inch engines anyways unless you have deep pockets. A year warranty goes by pretty quick!