| Author | Message | ||
     Djohnk |
I recently test drove two brand new bikes at the dealership: a Aprilia Capanord and a Triumph Explorer. They both have red lines significantly higher than my '07 Uly. I kind of liked that. I was thinking, my bike has almost 65K miles on it, probably will need engine work soon. Anyone have any insight on modding the Uly's engine/ECM so it can rev higher (9000+ RPM) and still be reliable. I think that would be nice also for road trips on some Texas highways were the speed limit is 85mph and you can go all day at 90mph without worrying about a speeding ticket ... the Uly as-is feels like it needs another gear going continuously at that speed. | ||
| Reepicheep |
Not a lot you can do, it's a long stroke engine, that's what gives such good low end torque, but it also means it can't rev that fast. The piston is simply moving too fast along the cylinder wall, and the lubrication film will not hold up. You could get a 9 motor (shorter stroke), and bore it out to a larger displacement, and put that in. That could probably rev to close to 8000 RPM. | ||
| Hughlysses |
The 08-up engine with its larger crankpin and bearings and improved oiling system is good for a few additional RPM (~500 RPM higher IIRC?). The engine swap is a PITA though (DAMHIK). If money is no object, I'm sure there are ways to achieve your goal, but they'll require major engine changes. The "easiest" thing I know you could do is buy and install an XBRR race engine- huge bore, short stroke, 1350 cc, and high-RPM capable. Of course you'd probably want some more street-friendly cams and the fueling would probably need a lot of work for street use. Instead of raising your engine's RPM capability, you could look at lowering the RPM requirement for the speeds you want. If you're not worried about low speed performance, you might find an alternative primary chain setup that would lower the engine RPM. Many people here have gone the other way by installing the XB9 primary chain/engine sprocket to get better low speed performance at the expense of higher engine RPM at speed. You might find a primary set from a tuber or Sportster that could be installed that would lower the RPM at speed instead. OTOH, if your Uly has held up for 60k+ miles being ridden like that, I wouldn't worry about it. Apparently it doesn't mind being wound out even if you do! | ||
| Djohnk |
Thanks for the advice you two. I will keep my Uly as-is. I decided I'm not going to sell it, even when I get another bike. Bikes are cheap (compared to cars). Will wait a little while longer to see the AX. | ||
| Tootal |
Engines and tires are two subjects that have one commonality, that's the word compromise! When you start looking at designing an engine you can never have it all, although, EBR's latest engine with the swirl induction seems to be very close to perfection! Our long stroke low rpm engines make great torque and are very efficient. If you look at a Ducati engine with it's short stroke and pancake pistons, it spins a lot of rpm but don't plan on great gas mileage! The big diameter piston allows for bigger or more valves in the heads so it flows way better than a small diameter long stroke engine. I have a friend who's an engine builder. He does Pro Stock engines to Harleys. His favorite Harley engine was a 117" "square" engine. In other words, the bore and stroke were the same. He said the way it revved out just seemed different than any other engine he'd built. I've always felt a square engine was the best of both worlds, a really nice compromise! I'm rebuilding my Harley engine right now and I just left it at 95" with the stock stroke. I bought new pistons and had Dark Horse Crankworks do their magic on balancing my crank. Once I got it back I kicked myself for not boring the cases and putting in 4" pistons with my 4" stroke. I could have had a 100" square motor for just a little more dough!  Oh well, it's a Harley. I'm sure I'll be taking it apart again someday!  | ||
| Jwblue |
Djohnk, I would appreciate getting your thoughts on the Capanord and Explorer, especially since you're a longtime Uly rider. Thanks | ||
| Djohnk |
I thought both were great bikes, they both sound awesome when you open them up above 4000 rpm, and handle well. I liked the Explorer the most, but of course it was about $3000 more than the Capanord. Compared to my '07 Uly ... don't see a reason to switch right now. | ||
| Jesse_lackman |
Djohnk, For more RPM the traditional methods apply, good rods, good balance job, more valve springs and cam. Wouldn't be hard to do just requires money. But check this out and forget about more RPM: http://streetfighterperformance.com/xb12-turbo He was up to 187 hp on the stock engine when it threw a rod. don't know if he's got the new engine running yet. Very impressive build. |
