| Author | Message | ||
     Remlap76 |
my 04 xb9sl had a small crankshaft mishap,so now i need to replace it and i am reading all the posts of a xb12 crankshaft in a xb9.now i guess my question to all is. will it fit? will there be the proper clearance on the heads? do i need to mill the case? so can any one shed some light on this topic? | ||
| Puddlepirate |
If you do a forum search you should be able to find the information you need. There are several members here who have done it successfully. | ||
| Id073897 |
i guess my question to all is. will it fit? Yes, but you will need the XB12 connecting rods and you'd best use the XB12 pistons too. Regards, Gunter (Message edited by blake on September 21, 2009) | ||
| Alex |
No, it won't. You will need the XB12 cylinders and heads and ... also It will fit just fine. XB9 and 12 cylinders are identical. XB9 and 12 heads are identical. (At least up to 2006/2007. In 2008 the crank design changed. But even that crank could be used) The pistons are not the same but they are simply interchangeable. So if You get an XB12 crank and pistons (and if You are willing to put new pistons in used cylinders) You will have the displacement of the XB12. Still the throttle body (especially throttle plate size) is different but it may even work with the XB9 parts. (Message edited by alex on July 17, 2008) | ||
| Puddlepirate |
Gunter, that is incorrect. All XB heads are exactly the same. All XB cylinders are exactly the same. The pistons and crankshafts are the main differences. | ||
| Remlap76 |
i am having my cylinders bored out a little. i am putting my xb9 pistons in with freshly bored cylinders and rings. so it should work. thanks for all the info. | ||
| Id073897 |
So I stay corrected and humbled. Never knew that they would indeed be identical. Regards, Gunter | ||
| Puddlepirate |
Again, if you're putting XB9 pistons in, your compression ratio will be too high for the street. You'll be around 12.3:1. Some of the guys here run that on racebikes, but I would not do that to my Sportster. | ||
| Remlap76 |
i thought that it would be around 11 or so as far as the compression. well then i should get some pistons that will be around a 11 ratio? | ||
| Viper9885 |
The compression that you get is right around 12.4:1 with 9 pistons in an otherwise 12 engine. I would do it if I were you as a matter of fact I will be doing it this winter. Japanese 4 cylinders regularly have comp. ratios well into the ellevens and even mid to high twelves, it will be perfectly safe on a daily driver as long as you ALWAYS put premium in it. what im planning on doing is putting a 1250 big bore kit on a 9 and getting a custom set of pistons made so I can still run somewhere around 11.5-12:1 compression and still keep the revs of the 9.....trying to catch up to those damn Italians is hard (Message edited by viper9885 on July 28, 2008) my bad, it is 12.4 to one not 11.4 (Message edited by viper9885 on July 29, 2008) | ||
| Puddlepirate |
Viper, you sure about that ratio? I haven't taken the time to calculate it myself, but two or three other people who have done it said that it came out to 12.3:1. Jap 4 cylinders are also engineered much differently, and are designed to work with hig ratios, with knock sensors to retard the timing, and different piston, valve, and combustion chamber design. That is like comparing apples to oranges. | ||
| Viper9885 |
yeah you are correct that they are built differently, but as long as you have access to 93 octane fuel, 12.4:1 is perfectly safe and reliable. The best thing you can do is buy yourself a heat barrier blanket for under your airbox (to keep intake air cool) and run an open airbox and 12.4:1 should be just fine AS LONG AS YOU HAVE GOOD GAS | ||
| Puddlepirate |
Are you planning to run that on the street or will it be a racebike? I'm sure she'll rip when you get finished with that!  | ||
| Packrat |
don't wanna sound negative there Viper, but It's gonna take a HELLUVA lot to get buell rpm's "up with Italians" My XB12 is what, 6,500 redline???? My '07 Tuono is 10,500, and that's factory stock.. | ||
| Viper9885 |
Ducati: Bore 4.09" x Stroke 2.54" Compression Ratio: 12.5:1 Displacement: 1099cc 2004 Buell XB9R: Bore 3.5" x Stroke 3.1" Compression Ratio : 10:1 Displacement: 984cc now don't get me wrong im not saying that you can turn a Buell into a Ducati, cause you can't. but what i plan on doing is buying a 9R (above specs) and putting the 1250 kit on it to knockout the bore. Then Im going to have a custom set of 12:1 pistons made. The only thing i haven't figured out yet is i need a set of slightly longer rods than the stock 9's rods (do decrease rod/stroke ration and increase revability). I would also like to de-stroke it but i am not aware of a matching shorter stroke crank on another Harley as stock swappable parts, but im sure its out there Besides the actual 1250 kit that whole procedure wouldn't be to expensive and you would have a very VERY fast bike. I'm sure you could rev the above engine safely all day to 9-9500 maybe ten (I'm not sure what the valve train is safe to however....) id have to actually ride it and feel it out. I suppose it does get expensive though cause you would need all the accompanying mods like: open airbox, a good exhaust, and most of all a good tuning program. sorry for kinda hi-jacking this thread  (Message edited by viper9885 on July 30, 2008) | ||
| Petebueller |
I think you will have problems with ring speed if you use an XB12 crank and keep the XB9 rev limit. Personally I'd go the other way. XB9 crank with a 1250 big bore. I think that this would make the extra HP more usable. If you want to use an XB12 crank I'd at least use the 08 XB12 pistons. They are made for higher revs, and I think that the compression is sufficient as it is. My 2c | ||
| Bombardier |
Sounds like you have a challenge ahead of you Viper. May be cheaper to graft in a 1125 engine and would be a lot more reliable. As you say the valvetrain especially with the steep ramp on the cams coupled with pushrods are going to need some serious valvesprings to keep the float monster at bay. With the little clearance you will have with 12 to 1 comp ratio it will not take much for a contact issue at 9 to 10 thou rpm. | ||
| Viper9885 |
yeah but overall the way i want to do it would cost.... right around 2 grand (MAYBE 3). Im sure a helicon is WAY more expensive than that. I would actually have to "de-tune" the cams slightly and use a longer duration and lower lift to smooth things out, along with some good valve springs but i still think it could easily be made to rev to 9500-10,000 and make about 105-115hp | ||
| Bombardier |
Check out the wrecked and repo ares for bikes. I would think that somebody has come undone somewhere by now. | ||
| Viper9885 |
yeah im sure you could put something together fairly cheaply, and i need something to keep me busy in the winter. | ||
| Bad_karma |
Adam Wish you luck but just some info to think about when targeting your goals. With the 3.1 inch stroke at 9500 rpm the piston speed will be 4948 fps. So here are the comparos. The 1098 has a stroke of 2.54918 with a piston speed of 4142@9750. The Super Duke with a stroke of 2.46 inches has a speed of 3690@9000. From HP books they offered these numbers Winston cup motors at 4900FPS and Drag racing at 5400. I would like to build a de-stroked large bore engine with around 4200 fps that is close to 8100 rpm. Good luck Joe | ||
| Viper9885 |
yeah like i said i want to de-stroke it but i would like to just buy a shorter stroke bolt in (or made to fit with slight modification) crank out of another Harley. I don't want to hijack the thread but does anyone know of a shorter stroke crank that would work to bring piston speed down? | ||
| Viper9885 |
a custom Buell motor with 3 13/16" bore and a custom 2.8 inch stroke would have a displacement of 1047cc and what would the piston speed be? the only thing is that with a 2.8 inch stroke the rod/stroke ratio gets way out of wack with the stock rods (12 or 9 are both too long) you would want to run something like a 6.3"-6.5" rod length to bring the rod/stroke back to almost the same as the stock 9 | ||
| Diablobrian |
The idea of grafting an 1125 motor into an XB chassis is BAD!!! The 1125 requires solid mounting and the chassis was drastically re-engineered for the stresses involved. what is the stroke on the XR750 flat track motors? I am a believer in the short stroke motors as long as you can efficiently fill and empty the cylinders, which is difficult considering the head design on the XB motors. A three valve head with 2 intake and one exhaust would seem advantageous to me if a down draft intake port could be devised with a lower included angle. The 4 valve heads have a tendency to burn the webbing between the exhaust valves because of the temperatures these motors run at. | ||
| Diablobrian |
On the compression ratios question: I run 11.43:1 on the street, and that is as much as I would go. I normally run 93 octane, but when I am forced to run 91 due to availability, it does start to ping. | ||
| Viper9885 |
yeah but with the 3 13/16" bore kit im sure you could drop a pretty decently big set of oversized valves in, with some headwork to match and get pretty decent flow numbers out of it | ||
| Bombardier |
Stresses!!??!?!?! Bombing the guts out of an already worked motor that vibrates it arse off is only going to put more stresses everywhere. The 1125 motor with its balance shafts is BMW like in comparison to the Sporty based XB engine and as the power output expected will be similar the stresses would actually be less with the 1125 than the bombed XB motor. Still do-able but with the short chassis it would be a wheelie champion whether you liked it or not! | ||
| Viper9885 |
*Still do-able but with the short chassis it would be a wheelie champion whether you liked it or not!* yeah i suppose, can you put a Uly rear (longer) swingarm on the back of an XB? With the Uly belt along with the XB12S (or whichever one has the lower rear spring, im not sure) spring to compensate for the increase in ride height from the longer swingarm. i know it would change bike geometry a bit but its not like it would make it completely un-ridable. Never mind im babbling and this belongs in its own thread, sorry Rem | ||
| Bad_karma |
Adam Using you 2.8 stroke here are a few comparisons. XB9 piston speed at max power is 3900 Ft/sec, you configuration gets 8500 rpm @ 3967 ft/sec. XB12 at max power is 4320 ft/sec, your configuration that would be 9300 rpm @ 4340 ft/sec. At those speeds I wouldn't want to add much valve weight or lift. I really want to do a short stroke over bore say like an S&S case with the offset lifters to get maximum bore then run the 9's stroke. With a none race case 4.250 bore is do able. With the race case you can get 4.8" bore. With the none race cases with a .850 offset case you can get 1453/88" and using the pro stock case you can get 1853/113". These numbers are using a 3.125 stroke (XB9). Of course these aren't cheap. Joe | ||
| Viper9885 |
if your going to go that far i would put that custom 2.8 or even less like 2.6" stroke crank into that 4.8" bore which would come out to being a 1500cc engine. With a nice set of 12:1 pistons and Directlink you would be set. |
