I was with Don and Rob from Guhl Motors yesterday. Fred H. has asked me to share my thoughts with all of you.
First, on Guhl Motors. I'm glad that Don described their location, otherwise I think I would have had a tough time finding them. Non-descript metal building behind an outdoor equipment retailer. I arrived a couple minutes before our agreed to time of 9AM and met Rob and Don. They gave me a run down on the business and Don explained what his intended approach was for the day. I immediately felt comfortable with them and their systematic approach to baselining performance and incrementally changing parameters.
We got the bike strapped onto the dyno and in short order they made the first of six of the pulls for the day. Don was very patient in allowing me to look over their shoulder and ask questions and take notes. The first pull was for top speed, with a HP of 131.3 and torque of 89.4 in fifth gear. I do know that Don seemed really excited to absolutely determine the factory 155MPH speed limiter.
Between the first and second pull, he reflashed the ECU to remove the speed limiter and he shifted the opening of the secondaries by four cells (to the left). Fuel was left as is. The second pull showed a top speed of 193MPH. HP went to 132.5, and torque increased to 91.70. NOTE: NO changes to the amount of fuel were made. The only thing that changed (aside from removing the speed limiter) between the first and second pull was a shift in the point at which the secondaries open. The amount they opened stayed exactly the same.
Don felt that he wanted to try going richer on the fuel expecting an overall performance increase. He felt that although the ratio on the sensor looked OK, he could squeeze a bit more performance out of it. He applied a 5% across the board increase and made another pull. Torque DROPPED to 91.24 and it seems like I didn't record HP but it was lower. It was around this time that Don called Fred H. and they talked for the first time, but not the last time of the day.
Seeing the the decrease in performance, he went 10% lean (from the initial adjustment, or 5% lean from stock) and both HP and torque went back up, 133.77 and 91.91 respectively. He was pleased with that but still did not like the performance above 8K RPM. The charts clearly showed it was WAY rich. He changed fuel settings at 9K to -11%, at 9500 to -16% and at 10K to -20%. He also changed a setting at between 3 and 4K of 2 or 3% and did two additional pulls. Both of these pulls were 5% lean from stock, except for the 9K and above range and the 3-4 K range as just described. First pull results indicate 133.60 and 91.91. Second pull was 133.52 and 90.61 which is what I believe is reflected in the screen shots he provided, which I've attached. Across the board, the torque is higher with these settings, and there is no weird stuff going on above the 8K RPM range.
He asked me to take it for a spin and let him know how it felt by seat of the pants. Not being familiar with the local roads or the local police, I was a bit limited in what I felt comfortable trying. However, my initial thought was that this bike has NEVER pulled as hard as it was then. I tried roll-ons in every gear and it just PULLED, hard. I always considered the bike fast, but this is different. The changes Don made greatly improved roll on power. I wasn't really aware that it was lacking in that area, but once you have the mod done, the difference is pretty clear. I think this is going to be very helpful especially when riding two up.
It's a 100 mile ride back home from his place, with the vast majority of it on 2 lane highways, and a couple miles on interstate. I played with 4th, 5th, and 6th gear roll-ons and there is no question about the changes being a big improvement. This isn't a quantum leap in performance, but it is very noticeable.
I asked Don where he feels he is in terms of marketing this re-map. He is certain that this is THE map for installation on a stock bike. If you DO NOT have aftermarket exhaust or air filters, or have removed the secondaries, this is the one you would get. I told him that I would be posting this information and that he should probably be prepared to start getting some calls. Right now, the only way to get this mod is to send in the ECU or take the bike to them. He is working on a plug and play remap interface, but I am not sure how long it would be before that is available.
I've offered my bike to Don in the future if he wants to try anything more. Don also offered up that if I do mod anything else (air filter, exhaust, etc.,) he'd run the bike again in order to develop maps for them.
I had hoped to get some two-up riding in the next couple of days to make an assessment but it looks like the weather isn't going to cooperate. As soon as I do, I will post an update.
Time for some new tires. 1100 mostly high speed highway miles in the past week plus those dyno pulls yesterday pretty well toasted the rear! It's got 4300 on it now. I've ordered a set of the PR3's and they will be installed on Thursday. Absolutely need them before heading to Maryland next Saturday to take the ARC Level 2 class.
I hope I've adequately explained things!
