Ever since H-D started utilizing fuel injection on their bikes, I have seen and heard both the positives and negatives on both sides of the argument. I was always impressed by the crisp throttle response, reliability, and performance of the fuel injection; but I also had a few questions. A few years ago, Harley started using O2 sensors making their systems a “closed-loop” which reads the O2 of the exhaust and then adjusts accordingly…or so I understood. Thankfully there are resources available to us to discover the ins and outs of just about anything one could desire to learn about. As for me, a V-Rod based website called 1130cc.com, I was able to research a little more about Harley’s stock ECM and fuel injection tools.
It seems there are many riders like myself who could not stand the EPA choked stock engine/ muffler combination. Besides sounding like a giant sewing machine, the stock pipes and mufflers weighed in excess of 30 pounds and also emit incredible heat. Because of the restrictions placed on H-D to make their engines compliant, the stock settings tend to run on the lean side. Many of the riders questioned the need for an new ECM tuner, considering Harley’s system was set up in a closed loop already, so therefore why would you need a tune? I myself was curious, so I added the D and D Fat Cat exhaust to my 2008 VRSCDXA along with a K & N Free Flowing air filter. I immediately heard the difference from stock, but to be honest, it seemed to really hit a dead spot down low. When taking off the line from a dead stop, the bike was almost a dog, as it would stumble and cough. Once I got her going, she was a beast running like a rocket, but upon letting go of the throttle, I was always welcomed to a series of backfires and explosions. Fearing I may have been running lean, I would check the plugs on the bike to make sure they weren’t white on the ends.
On a V-Rod, checking the plugs is a bit harder than a traditional big twin as you have to remove quite a bit from under the air box to get to them. Also, just checking the plugs in the garage will tell you the condition at idle, I was more concerned with WTFO, so I took half the upper end apart and took of for a straightaway to open her up. In 4th gear, just as I had opened her up to full throttle and pulled past 7500 rpms, I shut the bike off and coasted to the side of the road. Using quick hands and some hand tools, I was able to pull the plugs only to discover the plugs are white upon full throttle runs. I went to my current beacon of information here in Houston, Republic Harley Davidson, and asked Craig Slovak, the GM, for his advice on the situation.
Craig has recently spent several thousand dollars sending one of his techs, Joshua Thomas, to Harley’s V-Rod classes and training. Josh, a well respected drag racer in his own right, is the resident V-Rod magician at Republic, having enough experience to have taken the cases apart on one of the mysterious Revolution engines. He is one of 5 Masters of Service Technology Technicians at Republic.
“These engines are extremely simple. You can remove the crank without even touching the top end of the engine. Truthfully, one of the easiest engines Harley has ever produced to work on,” Josh recently told me.
After explaining my bike’s configuration and symptoms, Josh recommended Harley Davidson’s new Screaming Eagle Pro Super Tuner. Like many of the tuners available, this will allow the technician to fine tune my bike on the dyno, but with this software he would be able to make adjustments to the stock ECM across a much broader range of parameters rather than the typical points of adjustment. Basically he would be able to adjust my air to fuel ration from idle all the way through WTFO and every point along the way. He did tell me not to expect much more out of top horsepower, as the D&D is one of the best tuned pipes for producing horsepower around. What he was going to shoot for would be a much cleaner acceleration throughout the power. This tuner would be able to hold a 15 minute run in its memory tracking along 26 variable points. Joshua should be able to dial this thing down to pull like a truck and only stop when I do.
I dropped the bike off and when I returned several hours later I was greeted with a smiling Service Department. Josh was waiting for me with dyno sheet in hand. Like he had said, I didn’t gain much in peak horsepower, but I definitely had a much more linear power curve and my rev limiter was increased from 8000 rpm’s to 9000, which also adds to the performance on the top end.
As you can see from the dyno, I gained approximately 10 hp and 15 ft lb of torque at 3250 rpm’s. Also, on the initial run the bike hit 60 ft lbs of torque almost immediately and then didn’t start climbing until 3700 rpm’s, hitting a linear point at 4200 rpm’s and about 68 ft lbs. After the Race Tuner, the torque continually climbs from 65 all the way to about 74 ft lbs at 3500 rpms. The peak hp grows consistently, pulling all the way to 8000 rpm’s steadily. 8000 was the rev limit before, and now it stays pulling at 113 hp all the way through 9200 rpm’s, so I should also feel that in the top end. The air fuel mixture was set to stay above 145, almost hitting 15 as low as 4000 rpms, and Joshua set it up to stay closer to 13.5. This would probably affect my fuel mileage a little, but make for a smoother running engine. I didn’t buy the V-Rod to save on gas anyways!
I took the bike out on a short run the next day and did notice the improved low end grunt. Where I had a noticeable flat spot in the beginning of the rpm range, now the bike pulls like a train all the way through. I was braking the rear tire loose on normal take offs, which told me I hadn’t adjusted my throttle to the new power yet. While I didn’t notice a huge difference in sound, the bike does sound a bit crisper and seems to really respond to the fuel given to it now with fervor. The V-Rod was a monster before, but now she’s an absolute BEAST! With the tuner now being “married” to my bike, it means I am the only one who can use it and only with my bike. For a price just under 500 bucks and then the cost of a dyno tune, my bike is running stronger, smoother, and much cooler; so the price to pay was pretty conservative considering the rewards.
