| Author | Message | ||
     Khelton |
My Uly feels so good powering up past the 6,000 RPM mark, nothing like it... then all of it a sudden it signs off just as the grin gets big. What can be done to get another 1,000 RPM out of the Uly motor and would it really shorten the life that much ? | ||
| Treadmarks |
ECM spy may let you do this. I would love 1000 more rpms as well. I think the ported heads would love it, I just don't have the nads to try.  | ||
| Hughlysses |
In an interview with Erik after the XB12 was introduced, he said the one piece limiting reliability at higher RPM is the rod bearings. The 12's have a two-stage rev limiter based on what the rod bearings would handle. I forget the exact numbers, but you can rev to something like 6950 for 10 seconds max (to allow for brief over-revs during shifts) and 6800 sustained. He specifically said that engine durability suffered at higher rev limits. The 2008 models bumped the redline to 7100 RPM sustained by adding a bigger crank pin and the improved oiling system. I don't know if they still have the two-stage rev limiter or not. So, if you trade for a 2008 model, that'll get you almost 1/3 of the way to your goal. Based on what Erik said in the initial article, I'd say if you use ECM spy or some other means to raise the RPM limit on your 2006 by 1000, you might get away with it for short bursts, but you're eventually going to seize the rod bearings or break the crank pin, either of which is going to REALLY screw some things up. You'd probably be a lot safer trying to raise the rev limit on a 2008 bike by 700 RPM. | ||
| Khelton |
Tks for the info, Hughlysses.....doesn't sound like it's gonna happen. What kind of RPM do the roadracing Buell's turn ? | ||
| Dentguy |
Just remember, more RPM doesn't always mean more power. Sometimes it just means more noise, floating valves that hit pistons and damaged rods/crank/bearings from trying to spin those big pistons. | ||
| Sanchez |
> he said the one piece limiting reliability at higher RPM is the rod bearings A friend of mine's XB9 locked up on him, and it did indeed turn out to be the rod bearings. They fused to the crank. He had to ride bitch on my Uly for the better part of an hour to get a truck.  | ||
| Spike |
For what it's worth, the original reported redline on the XB12 models 6800rpm with a staged rev limiter that would limit it to 6200rpm sustained after a few seconds. The '08 XB12 motor now revs to 7100rpm for a few seconds and then dials back to 6800rpm. The '08 Buell Technical forum says that the new 6800rpm sustained rev limit is up from 6400rpm, so I may be missing an update somewhere, unless that's a misprint. As Hughlysses noted, the big difference on the '08 motor is the crank pins along with the oiling system. The long-stroke Buell race motors have been known to run 7500-8000rpm, but from what I have read the motors that turn that rpm are always short lived. This is why most racers that are going for rpm will use the short-stroke XB9 crank and go to a bigger bore to get displacement back up. | ||
| Hughlysses |
The one sure way to get that kind of usable RPM increase is to find yourself an XBRR plant and drop it in your Uly! You know, that's probably the worst thing about the intro of the 1125R; I doubt you'll see anyone building their own streetable XBRR any time soon...  | ||
| Unibear12r |
Nope you didn't miss an update Spike. The original 12s hardlined at 6800 and then fell to 6400 sustained.  | ||
| Barker |
FYI 1125R max HP is @ 9500 rpm Redline is @ 10500 rpm. For this bike power goes down with 1000 xtra rpm Race kit can get you more power across most of the rpm range. |
