Exactly. Turning cruise on is a set of parameters that must be met. If engine RPM doesn't match what is expected in any gear for the vehicle speed, it will not know what gear it is in and therefore no cruise control.

The solution is to eliminate the pulley and install the one with the OEM ratios.

FWIW: changing this pulley will void your warranty if they find out about it regardless of whether you tune or not, because you've done something to tamper with the odometer in doing so.

 

Everyone else seems to understand this, but I am having trouble. To ME, a "pulley" works with the belt and "sprockets" work with the chain. Did you change one of the sprockets inside the primary? That is the only thing that change the ratio between engine RPM and transmission output shaft RPM. If you changed the belt PULLEY, none of this makes any sense to me.

 

There are two sets of ratios you can play with. The first is as you mentioned, the sprockets in the primary drive. The second are the pulleys that make up the belt final drive system(?). The standard front drive belt pulley is (usually) a 32 tooth pulley. The (usual) rear belt pulley is a 66 tooth pulley, but on my RKS the rear pulley has 68 teeth. By upping the tooth count on the front pulley to 34 teeth, more belt is pulled around for each complete rotation of the pulley. So, for the same RPM at the transmission output, you go faster. Or, you can achieve the same speed as before the pulley change with less engine RPM.

The engine RPM change that occurs when swamping from a 32 to 34 tooth pulley is about 6.5%. The down side to this modification is a slight hit in acceleration. But, the benefit of this mod is a lower cruising RPM at interstate speeds.

You can go the other way and put a 30 tooth pulley into your ride and get a slight increase in acceleration, with a 6.5% increase in RPM at interstate speeds.

Hope this helps.

 

Do the late model bikes now use ABS pulses to measure speed? With no change inside the primary, the ratios of engine RPM to transmission output shaft RPM remain unchanged. The only thing that changes is engine RPM to ABS pulse ratio with a pulley change.

 

Hey n Howdy all.

They say that “all good things, come to those who wait”.

The short answer is that I worked with Fuel Moto USA to get the bike tuned & everything is working great. Thanks to Lucas, from Fuel Moto, who nailed it on the first tune. Bravo!

Thanks for all the responses from the forum members who steered me toward getting a tuner. Y’all were correct, in that, you can’t adjust the parameters needed to correct for installing a 34 tooth front belt pulley without the access that a tuner gives you. The previous statement applies to my 2023 Road King Special. This is the third time I’ve changed the front belt pulley on a Harley, and this is the first time I’ve had to tune for it. I don’t know if that was because of the RDRS or if it’s a “2023 bagger” thing. Your experience may vary.

The DynoJet PV-3B gave me access to more settings and tables than I care to play with. Luckily, I had the assistance of a subject matter expert with just a phone call. The Fuel Moto team (Lucas) ended up “adjusting” the gear ratio settings to make the ECM happy again. I was told to leave the VSS settings alone until we tested the tune with the gear ratio changes on the bike. That was excellent advice, since that change worked perfectly. While changing the gear ratio settings may seem like "killing a cockroach with a sledgehammer", in the end the roach is dead and your problem is solves. So......

The tuning process was too easy. After talking to Fuel Moto, they made a tune and e-mailed it to me. Within 10 minutes of hanging up from talking to them, I had the tune saved to my PC, uploaded to the PV-3B, and the bike tuned. The resulting test ride was kind of anticlimactic, in that everything worked. No fuss, no drama.

I've learned quite a bit about the tuning parameters available using the DynoJet tuner and I’m continuing to research how the tables and settings affect the bike’s performance and rideability. As I get more confident in “adjusting” things, I’ll start working on using the PV-3B for more than auto-tuning while I ride.

Again, thanks for everyone’s assistance with getting me here. The RKS is happy again & so am I.

 

Has your speedometer accuracy changed? Higher than actual speed, lower than actual speed?

 

Weirdly, the analog speedometer reading didn't change after the front belt pulley change or flashing the Fuel Moto tune. Both the previous Harleys I changed the front pulley on had the effect of lowering the RPMs and Speedometer readings. The fast speedo reading lowered to inline with my GPS readings on both the Fatbob and Fatboy. This one, not so much (yet). But I'm working on it.

The speedometer is still reading high, I'm talking about the steam gauge in the tank console. During a test ride, I was watching the GPS speed on my phone and I had the bikes VSS speed, along with a few other ECM data streams, displayed on the PV-3B. The ECM VSS & the GPS were within 1/2 to 1 MPH of each other, with the VSS showing the higher reading. The needle on tank gauge was pointing 2 to 3 MPH high at 65 to 70. Now that I have access to the VSS data settings, I'm going to have to experiment a little to see which one is used for the analog gauge. The below pics are from the Quick Tune & VSS menus. I'm working on an answer to what the 4 entries do. The documentation on the VSS setting and "How to set it" PDFs only show one entry point available to change/update the pulses per mile/KM.

 

Your speedo reading is from the wheels. The vss on the tranny was eliminated in 2021 if I remember right.

 

Hey n Howdy all.

Figured I’d give the last update and conclusion to this adventure.

I’ve “adjusted” the VSS menu setting for “VSS Factor” and the HD speedometer is reading perfectly in sync with the GPS. You can see from the Before & After pics below what changes I had to make to sync everything up.

I didn’t adjust the front or rear vss, or the offset as the vss speed from the ECM and the GPS were within a ½ to 1 MPH of each other. I can revisit that if needed.

To sum up, one 34 tooth front pulley, plus one DynoJet (from Fuel Moto) tuner, Plus one Fuel Moto Tuning expert (Lucas), Plus a little deductive reasoning, equals one happy Road King Special.


Before adjustment Final settings