If you are a serious rider putting a lot of hours on your bike and see tons of highway miles then you know how important it is to have a smooth and well running motorcycle. You always hear about motor hop-ups with pipes, air cleaners, headwork, and so on, but what about hopping up the transmission? In this case we needed to do just that.
Uncle Vic's '02 Road King needed a transmission makeover. A few months ago we installed a 106ci motor hop-up kit from S&S Cycle, and we were very happy with the turnout. The bike runs very well with loads of power, the only thing is, now in Fifth gear and at top-end speeds it feels like the pistons are going to fly out the top of the cylinders. We needed to bring the rpm down without losing speed. Enter the Baker Direct Drive six-speed (DD6) transmission. The DD6 features First, Second, and Third gear straight cut to prevent lateral tension in those high torque, short-used gear ranges, and Fourth, Fifth and Sixth gear are helical cut for a smooth and quiet ride in the cruising gears. With the DD6 we should get a 15 percent reduction in rpm gaining a much smoother ride.
Also a 28-tooth compensating sprocket is included to dampen vibration in the primary so the bike can go the long haul for years to come. With the overdrive obtained through the primary this will also reduce strain on the starter by 14 percent (due to the bigger sprocket) and low rpm in the primary reduces noise in the trans case.
We stopped by Horn Cycle Works in Pomona, California, to get the DD6 installed as we snapped some photos. Shop tech Nolan placed the '02 Road King on the lift and started draining the fluids and removing all the big parts that would be in the way like the exhaust system, running boards and the primary.
1. Here is the DD6 kit, the assembled gearset on Baker's bearing door, the shift drum with redundant Neutral pillow blocks, shifter pawl, main bearing and snap ring, shift forks and rod, 28 tooth compensating sprocket, Neutral switch, chain tensioner pad, new primary chain, race, main seal, and speedo recalibration tool. Retails for $2,596.95. Also seen here is a speedo recalibration tool that is sold separately for $135.
2. Nolan removed the outer primary then the clutch set and hub along with the chain, the adjuster and front compensating sprocket. Then he removed the starter and unbolted the inner primary.
3. Then the transmission pulley and locking plate were removed followed by the primary race (arrow) and the old seal.
4. On the other side of the transmission, the end cover and top lid were removed. Then Nolan unbolted and removed the shift drum along with the shift forks
5. At that point Nolan removed the stock shift pawl and gearset.
6. Here is a look at both gear sets, Baker DD6 on the left and the H-D five-speed on the right. The overall length of the mainshafts and countershafts are the same. What you can see is how Baker is able to fit one more gear in the same amount of space.
7. Once everything was cleaned and inspected, Nolan installed the new main drive bearing and retaining clip. Then with the help of a JIMS bearing tool, Nolan installed the mainshaft drive gear also known as Sixth gear into the case bearing.
8. Next, the Baker shifter pawl was installed into the case, the stock H-D pawl will not work with the new shift drum. The Baker drum was designed to provide ease and smoothness of shifting. Once in place a new snap-ring was installed on the outer shaft of the case to keep it in place.
9. Nolan placed a new door gasket in the case then installed the gearset, everything went into place very smooth.
10. Then the bolts for the exhaust bracket and the bearing door were treated to some blue threadlocker and torqued to 14 lb-ft.
11. At this time the shift forks were put into their proper place then the fork rod was slid through the case.
12. Next, the shift drum and pillow block were installed, Nolan made sure all the shift forks were aligned and properly riding on the drum before bolting them in place, he torqued to 9 lb-ft.
13. Once the drum was in place and bolted down, Nolan adjusted the shifter pawl. There is a setscrew and lock nut on the outside of the case on the left side. This is needed to allow the pawl to move back or forward on the dowel pin to align the drums. This is done in third gear and we wanted the pawl to be in the center of the detents (arrow).
14. The stock oil slinger was re-installed with a new cover gasket...
15. ... followed by the trans cover. Nolan checked that the clutch cable was in good shape and still connected to the ball and ramp assembly, then he bolted the cover on and torqued it to 9 lb-ft.
16. With the top cover still off, Nolan filled the case with trans fluid. He wanted to cover the drum, the rod, and the shift forks before starting the bike just to make sure that everything was lubed. Then he installed a new gasket for the cover.
17. Next, a new Neutral switch was installed along with the speedo sensor. This kit comes with a gasket for the speedo sensor, this is more like a shim, it spaces the speedo sensor up a bit to keep it from hitting or rubbing on the gear pick-up. Normally the o-ring is all you need to keep the oil in the case but just to be safe the gasket is there.
18. With the transmission done and the case closed Nolan installed the pulley and new race onto the mainshaft.
19. Then he installed the inner primary and starter assembly.
20. With the new 28 tooth compensating sprocket and primary chain the clutch hub assembly was installed as one into the primary. Then the new chain adjuster shoe and the all the clutches were installed and the clutch was adjusted.
21. Then the exhaust pipe and running boards were re-installed. With this setup there was no exhaust pipe clearance issues, it's the same as stock just with an extra gear.
22. We took the bike off the lift and headed out for a few test miles.
After, the bike was placed on the dyno to see what the difference in rpm is at different speeds. But first we needed to re-calibrate the speedo. The speedo recalibration tool comes with a speed sensor conversion box, once the bike is up to speed you can see how fast you are going on the dyno and make adjustments up or down to sync up your speedo to match the speed by pressing the button. This will stay on the bike so once we were done it was tucked under the seat.
23. Once the bike was dialed in Nolan got the bike up to speed. At 65 mph in Fifth gear the rpm was 3,050, then we shifted into Sixth gear and the rpm dropped to 2,490. Next, we took the bike up to 80 mph in Fifth gear and the rpm was 3,690, but after shifting into Sixth gear the rpm dropped to 3,120 and felt as smooth as when we were at 65 mph. With all the highway riding Uncle Vic likes to do this will make the biggest difference, maybe more than the motor hop-up.
**Side note: After just the first week of riding the bike and how well it felt to ride at the higher speeds, Uncle Vic called to tell us that this was one of the best things he's done to the bike. He even noticed a gain in gas mileage, about 25 more miles to the tank.
Horn Cycle Works
9804 E. Saginaw