Hi Guys, well it's just about time for my winter motor rebuild an I have been doing lots of homework trying to work out my best options. I am seriously considering just taking the easy route and ordering a 120st or 120r and I have a few questions.

first, my bike is a 04' road king, The screaming eagle catalog has the 120r available for my bike but not the 120st. Anyone know why the R would fit and not the ST? My parts guy says the ST isn't available for my bike but my two mechanics both say it should fit no problem. Any ideas?

Second, my need for speed has me wanting to go straight for the 120R however I am concerned about the longevity and reliability of the motor. How does the 120R behave in traffic,long rides,around town, etc? How many miles do you have on your 120r and would you buy one again?

My main goal is to have a streetable 120/130hp motor and I would like to keep it Harley. Other options I am considering is boring my cases and going with a 113ci kit, screaming eagle heads and stroker flywheel and maybe a 20-30 shot of nitrous. Option three is keeping my stage 2 88ci and bolting on a turbo. The turbo idea is sexy but again I am worried about heat and around town riding.

Please share your experiences with your 120st/120r motors. Thanks so much for your help and guidance guys!

 

ST is the cali version of the R. I believe that it is smaller cams, but not fully sure on that.


It will fit, but since you are not in cali, why not get the "R"?

 

Yes I believe you are right, the only difference I could find in the two motors is the cams.

I would prefer to go with the R, I would just like to hear from some guys running one and get their thoughts.

 

From what I have read on this Forum, I think the ST has a warranty and the R does not.

 

I have a 120r in my 2013 street glide with just over 20,000 on it. It has been trouble free up until now, have a base gasket weeping (not bad, but annoying). It does everything ok, slow in town, fast on the highway, no spark knock, I did change the lifters at 10,000 and changing them again now, the valve springs are a little to strong and I'm changing those also to AV&V 6500. It always puts a smile on my face but if I were to do it again I would go with the S&S124 or maybe the 143 $$$$.

 

The ST is identical to the R in all respects except the cam and tune. The ST has the SESPT tune and the R has the track only tune.

I had a R put in a 13 Street Bob with the track tune as it was for running on the strip. I put a ST in a trike which is not an "authorized" use. HD has only authorized it for 15 and later Touring only two wheel bikes.

The only difference in installing either is if the bike 120 goes in a throttle by wire it gets a 58 or 64 mm throttle body. If it goes into a throttle cable set up there is a 58 or 62mm versions available. The ST comes standard with the 58mm throttle body. The R does not come with the throttle body you must pay $.

HD would not allow a SEPST tune for an unauthorized installation. The tech simply installed the track tune in it and all was good.

HD did say that even if the 120ST goes into a unauthorized bike they would honor the 12 month warranty on it. I could give a crap about warranty.

Both will bolt up to any 6 spd in a Dyna or touring.

I have 3K on the ST and 2.5K on the R. They have run faultlessly with zero issues. The R at idle does not like it with it's radical cam. The ST idles like any TC.

 

Thanks for the response, is changing the lifters every 10,000 miles normal for these motors? Also what is it about the 124 you think would be better then the 120R? Thanks again for your insight.

 

Thanks for the input. My transmission is a 5 speed, which is why my parts guy said it would bolt up. any ideas if either would bolt to a 5 speed? The R is listed as available for 02-06 touring bikes. thanks so much

 

And the compensator? Mine was shot just under 5K, the lifters were gonna be next but I traded up lol. Would i do it again, no!

 

Would you mind expanding on why you wouldn't purchase again? Thanks for your input!