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[SDCVO]

After over a year of torturing myself over what upgrades to do to my motor I have finally decided to go with a new crate 120R. I have seen people recommend the 58mm but looking for advice. I am still looking for "bottom end"...

[hd-dude]

The SE 58mm is the best bang for the buck. Add the 5.3 injectors as well.....

[Twolanerider]

After over a year of torturing myself over what upgrades to do to my motor I have finally decided to go with a new crate 120R. I have seen people recommend the 58mm but looking for advice. I am still looking for "bottom end"...

One of the happiest campers I know with a nicely touched up 120R is Scott Dunbar.  Here's his post from about a year ago well in to the service life of his engine and describing what he did after getting it to really dial it in:

If it's a 2012 - 120r motor, it has the upgraded billet cam plate and high volume oil pump.  The lifters are SE lifters, but are not made by JIMS.

When I installed my 120r, I replaced the cams with T-Man 662-1 cams, upgraded the clutch with a BDL kit (purchased from Jim) along witha VPC 92T variable clutch kit, installed a 55mm HPI throttle body with 5.3 injectors and installed a Jagg 10 row oil cooler...

I'm at 15K on the motor and am happy!  

[sadunbar]

One of the happiest campers I know with a nicely touched up 120R is Scott Dunbar.  Here's his post from about a year ago well in to the service life of his engine and describing what he did after getting it to really dial it in:

The 55mm HPI throttle body I run flows very similar to the 58mm SE throttle body Jim suggests.      IMO either is a good choice for the 120R.

For what it's worth, I started out with a 62mm HPI throttle body on my 120.  The low speed driveability of the 55mm HPI throttle body is much improved as compared to the 62mm HPI throttle body.  I had the bike on the dyno with both and there was very little difference in the results in the RPM ranges I actually ride in.  The 62mm produced slightly better numbers at WOT.  The 55mm produced better numbers down low... 

[prodrag1320]

we`ve used the 58mm on the 120R`s with very good results,guys are very happy with them

[jlsnyderCVO]

I'm running a 58mm on mine and I've got no complaints.

[hrdtail78]

The 55mm HPI throttle body I run flows very similar to the 58mm SE throttle body Jim suggests.      IMO either is a good choice for the 120R.

For what it's worth, I started out with a 62mm HPI throttle body on my 120.  The low speed driveability of the 55mm HPI throttle body is much improved as compared to the 62mm HPI throttle body.  I had the bike on the dyno with both and there was very little difference in the results in the RPM ranges I actually ride in.  The 62mm produced slightly better numbers at WOT.  The 55mm produced better numbers down low... 

We have seen the same here.  One major plus about the HPI 55 is you are not pigeon holed into air cleaners.
 

[HD Street Performance]

Depends on your goals and the level of tuner at your disposal.
The SE58 is a good commodity grocery getter and a throttle hog by S&S offers more even with the OEM cam. The throttle hog is at a very good price point too.

[JohnCA58]

Like Don says, the tune is what makes or breaks it,  I also very happy with my HPi 55 and produce great hp and tq.  I am using the HPi 6.2 injectors    throttle sensitivity was important to me, this is a everyday bike.  the 55 is manageable.

[SDCVO]

Depends on your goals and the level of tuner at your disposal.
The SE58 is a good commodity grocery getter and a throttle hog by S&S offers more even with the OEM cam. The throttle hog is at a very good price point too.

What size throttle hog would you suggest then, 58mm?

[SDCVO]

Like Don says, the tune is what makes or breaks it,  I also very happy with my HPi 55 and produce great hp and tq.  I am using the HPi 6.2 injectors    throttle sensitivity was important to me, this is a everyday bike.  the 55 is manageable.

Does anyone know of "that guy" to tune it in the San Diego area? I completely agree that is is hugely important!

[HD Street Performance]

Perhaps Cycle Visions
58 or 66mm either
The nice part of the TBW is it can be buffered to cure parking lot manors at low speeds.
The 120R I helpd a guy in Mich. with, heads and build design went 148hp/130 and that was with the stock cam.
It has a 66mm TB and 201 CCP compression, Wengler 2:1.
One other 120r "B" motor that got switched to 124" same heads and same CCP with 662-2 cam went 140/146 with 58mmTH and Boarzilla with Trapp IIRC. Big fat torque curve on this one.
Consider the lower torque number on the first as a result of the pipe mainly, it is huge. The torque curve was flat however and was still far over 100 at 5500rpm.

[SDCVO]

Perhaps Cycle Visions
58 or 66mm either
The nice part of the TBW is it can be buffered to cure parking lot manors at low speeds.
The 120R I helpd a guy in Mich. with, heads and build design went 148hp/130 and that was with the stock cam.
It has a 66mm TB and 201 CCP compression, Wengler 2:1.
One other 120r "B" motor that got switched to 124" same heads and same CCP with 662-2 cam went 140/146 with 58mmTH and Boarzilla with Trapp IIRC. Big fat torque curve on this one.
Consider the lower torque number on the first as a result of the pipe mainly, it is huge. The torque curve was flat however and was still far over 100 at 5500rpm.
Do you know the guy at Cycle Visions?

[TorqueInc]

  Throttle hog....price be damned its a much better tbody than the se airflow wise and has recently proven itself to make more power.

  And as Jason said it does suck that the AC options aren't great

[RayG]

I also have the 66mm TB, but I went with the S&S 124.  The 58mm can usually be purchased at a decent price.  The S&S Throttle Hogs have to be sent back to S&S so if time is important you will have to consider that.  In my case it was cheaper to have my 50MM sent out to S&S to be modified but I would have no problem using the 58.