It's common to go to a 39 or 38 tooth rear sprocket, I like the 39t as I ride 2-up a lot, others prefer the 38T.

Honda actually went to the 39 on the 750RS,,,

 

I jumped from the stock 17/41 sprocket combo straight to a 18/38 combo with modifications & loved it as 4th gear was now like the old 5th gear, so I now had a super 5th gear overdrive. But……..after trying the 17/38 sprocket combo, I feel that this combo is ideal for the 750 engine as it does not have to work as hard pulling at interstate speeds, especially when riding 2 up, going uphill, or riding into heavy headwinds. My 03 750 ACE does have a Stage 1 jet kit along with a 4 degree timing mod which helps with low & midrange torque/horsepower. Also, I came across an article showing more engine wear loading an engine vs running more RPM’s.

 

I jumped from the stock 17/41 sprocket combo straight to a 18/38 combo with modifications & loved it as 4th gear was now like the old 5th gear,

I always prefer changing front sprocket by 1 tooth vs. changing rear by 3 teeth, because both sprockets can share the same chain length, but in some thread a forum member had suggested that there wasn't enough room inside a 750 housing for an 18T. Did you have to do anything to housing or front sprocket to get enough clearance for 18T?

 

A good ask, because I'm on the same ride he is.

@chrisxxx9876 I'm on a 38t rear 17f, if you change only the rear get a 120 link chain instead of the stock 122, the change in sprocket size leaves too much play and throws off the adjustment thresholds. You'll be replacing way too often.

 

I went with the bilski 38 toother and I gotta say she's a totally different bike now it's worth the investment!

 

QUOTE="Megajonboy, post: 5626080, member: 303947"]
I went with the bilski 38 toother and I gotta say she's a totally different bike now it's worth the investment!
[/QUOTE]
+1 for 38T - I also went with 38T and is indeed a Totally Diff Scoot, and bout 400rpm diff at 70mph ( from about 4100rplm to 3650,...
And Honda on the Rs (Vt750RS) uses a 38T , Not a 39T as previously mentioned

In fact I use the OEM RS Sprocket(38T) on my scoot, cause the OEM Honda 38T sprocket (milder steel) runs a good bit quieter than my First JT Srcketset (Harder!! Steel) did.
The JT Sprockets for our Honda's run and wear well ( NoProb), But do run with noticibly more runnin noise - especially with stock exhaust, and very noticable when goin over bridges or anywhere there's a barrier on the side a the road.
Hey, it's nit, JT sprockets run fine and well - I'm just aged and like smooth, quiet & comfortable (OEM Honda Sprokets(milderSteel) DO run quieter).

Oh Yea - a 38T rear sprocket - Nice!!! mod... ( and new 120 link chain - Perfect fit(NoProb)
Don't mess with the front sprocket size!, that's a older Harley thing, twas easy and with a wide selection, but not for our honda's -
Can Be Disastrous!, There's not much clearance up front on out Honda'a to Start with - Dont make it Even Less (notch & grind)
Ever lost or broken/snapped a Chain. They always break.snap on the top(pullin) run, and that top loose end gets pulled thru & aroun that front sprocket area - and can take out Anything! Everything! that's in its way - including the whole left side cover and Crankcase!!! One's usually on the throttle pretty hard when the chain breaks and the loose end gets Sucked, doubled, folded, Whipped thru that front drive sprocket area - Well, Don't ask, I Know, can be Big Trouble and even Bigger $$$$ than one even wants to get close too....

A simple 38T and 120 link - quick easy & No Problem....

 

dang, that is an 8, I'm remembering 39, not sure which is worse, my eyesight going or my memory going.

 

DonWorryBout it, I apologize for the less than tactfully way i mentioned that, i wrote it too fast...

Have made much bigger mistakes than that:
See, I was practicin wheelies one day, tryin to learn to not have the front end of a Sportie come down so hard and the chain snapped...
Oops. wiped out the whole sprocket side cover and crankcase - that twas Big Foolishness!
So, Don't even think a messin with the front sprocket area and clearance on our Honda's!
Anything with any HP suckn up a loose ended chain is Destructively Dangerous!
That' was the intention of the post.

 

Don't mess with the front sprocket size!, that's a older Harley thing, twas easy and with a wide selection, but not for our honda's -
A simple 38T and 120 link - quick easy & No Problem....

True enough for the Shadow 750s with chain drive, but only because Honda based the engine on the VT600 engine and didn't scale up the transmission when they increased the capacity. But, if somebody is running the factory 16T on their Honda VLX, there's room to go up one tooth, and if they are riding a Honda VT400 Steed on a 15T, they can go up two teeth in front with no issues.

On my Suzuki, there was plenty of room for a larger sprocket and my Enfield accepts a front sprocket THREE sizes larger than the factory installed, without problems.

The beauty of a front sprocket change is that radically different ratios can be implemented without much hassle. Changeover on the VLX involves loosening the rear wheel, removing one bolt and one clip, take off the sprocket cover, two more bolts to unfasten the front sprocket, changeover, reassemble and tension. The whole job can be done in a 20 minute gas stop, without jacking the bike or removing the rear wheel. Same deal with my Suzuki 250. So much cheaper and easier than a rear sprocket change!

And, because there's no requirement for different chain lengths, I could, for example, ride cross country on my 17T, and when I get to San Franscisco, pull a 15T out of my saddlebag and install it at a gas stop, adjust the rear wheel back by 5/8", and ride the hills with a more appropriate ratio, and not needing to slip the hell out of my clutch at takeoff.

It's not just an "old Harley" thing, each model should be assessed individually for front sprocket clearance. Of course, ease of access to the front sprocket is a big factor.

Chain driven Shadow 750 riders got "shafted". If the rear hub geometry allows, it would be desirable to go even lower on the rear sprocket tooth count, so one could achieve the same "swap the front" functionality. For example, if somebody was riding a 750 Spirit that came from the factory with a 17/42, they could replace their rear sprocket and chain (just as you suggested) to get into the following situation. What you failed to recognize was that by doing so, one creates the opportunity to benefit from subsequent FRONT sprocket changes, even on a Honda Shadow 750.

Stock: 17/42 (.405) 122 links

Highway: 17/38 (.447, 10% steeper) 120 links
San Fran: 15/38 (.395. 2.5% shallower) 120 links

 

On my 01 Ace with a Dyno jet stage 1 I did the 17/38 tooth sprocket with a 120 tooth gold chain . I do like how the rms are down on the high way but honestly miss a little of the down low power. Next time I will do the 39 tooth sprocket and I’m keeping my eye out for v&h pipes with a dyna 3000

 

Changing the front sprocket on a Harley was around $400 labor as you have to pull the inner and outer Primary chaincases and clutch, I can see why people didn't go there. Maybe not on a newer model, or Sportster as the belt/chain is on the right side..., not familiar with new harleys or the Sportster.

 

"
True enough for the Shadow 750s with chain drive, but only because Honda based the engine on the VT600 engine and didn't scale up the transmission when they increased the capacity. But, if somebody is running the factory 16T on their Honda VLX, there's room to go up one tooth, and if they are riding a Honda VT400 Steed on a 15T, they can go up two teeth in front with no issues."

This is a common fallacy, almost nothing swaps between the VT600 and the vt750 transmission, the 750 is beefier, shafts, bearings, and it a 5 speed (OK there are 5 speed VT600C out there in Asia}
The layout of the transmission is similar, cases and such, but you can say the same of a host of other bikes in the family, Africa Twin, Hawk GT. Trans Alp, Deauville etc.

I agree that Honda could have changed the RC44 gearing from the start with a better choice, but at least nobody got the shaft. (-;
Mine is geared 16 x 44 and it leaves the harmonic drone behind early and then it's a high frequency buzz which doesn't go away just like a VT600C.
The 17 x 38 is so common it almost appears stock in the wild, it will make a slow bike slower, but it reflects how the bikes are ridden in real life.

If there are absolute nuts out there there is a solution pointed out to me by the member @Froth. The fifth gear set from the later shaft drive 750's will swap, drop right in and provide an overdrive situation. It sounds cool, so the next time you have your crankcases apart it maybe worth remembering. (-;

Added fun point to ponder over: the first 750 Spirits in 2001 came with 17 x 42 gearing and it was worth a 0.1 seconds in the quarter mile over the 17 x 41 bikes.

 

This is a common fallacy, almost nothing swaps between the VT600 and the vt750 transmission, the 750 is beefier, shafts, bearings, and it a 5 speed (OK there are 5 speed VT600C out there in Asia}
The layout of the transmission is similar, cases and such, but you can say the same of a host of other bikes in the family, Africa Twin, Hawk GT. Trans Alp, Deauville etc.

I wasn't suggesting that the RC44E used the same transmission as the PC21E. What I was trying to say, but did a very poor job of, was that when Honda scaled up the displacement they didn't provide more clearance between the output shaft and the shifter shaft. Perhaps they anticipated using a 16 tooth sprocket, like the VLX, but later decided to go with the 17T. They could have had the same final drive ratio as the 17/41 with something like a 16/39, and left riders with the option of going up or down in front to tune to their personal preference.

I don't know about the RC44E, but the PC21E on my VT600C was clearly designed to allow EASY changeover of the front sprocket, as I described earlier. By the appearance of the gasket outline in the pictures below, it appears that the 750 engine is similar.

The family resemblance between the PC21E and the RC44E seems pretty clear:

 

The sprocket shaft is different but it is the same engine family with the same limitations on gear sizing, they all kind of weirdly evolved over time to meet varying needs.
With the VT600 being earlier it is less compromised as an example, the shifter is the same between the two of them it is profiled to clear 16 teeth and never changed for 17.
I agree it is messier than a clean slate build, but that not unusual across the industry, where a base engine design may serve various models for years.
All in all I doubt Honda gives a damn about easy gearing changes for joe enthusiast with a cruiser.