| Author | Message | ||
     Jstfkndi |
Hello all! I am a first time Buell owner, but not first time bike owner and had a question or two if anyone could help me. I have an extra motor that came with my bike that needs a rebuild and I wanted to put a larger piston kit in it. I have done some research and am not sure I want to got too large a bore because of thinning the case walls. A 1250 does not seem that impressive with me and a 1447 seems risky. I have heard of 1340cc kits that are available, but would like to get some information from someone who has done this already. It will be a daily rider, so I am not trying to make it extremely aggressive, but wouldn't mind a cam with that kit. Basically, I am trying to find out what has worked\not worked for some of the people who have done this and if there is anyone besides Baker who makes a 6 speed that doesn't cost $2500!! I realize I am a newbie and if this email infringes on any kind of etiquette, then i apologize, but i am thirsting for some knowledge on this. BTW, the model I ride is an 04 XB12R. Thanks! | ||
| Xl_cheese |
Adding xb9 pistons to the xb12 engine will give higher compression and more power. | ||
| Rydberg |
I think there should be a factory 14 kit. They do it for the big twins. Why not be able to go to the dealership and have them (under warrenty) give you a Big Bore kit. | ||
| Rydberg |
To answer your question, Baker is worth the coin. And these XB motors run hot stuffed up under your ass already. I wouldnt go bore'n out the walls (on a daily driver). Go with the 9 pistons, cams and Baker gears and you will be a happy boy. | ||
| 2008xb12scg |
This is a link to one of the sponsers http://www.cycle-rama.com/index.html | ||
| Js_buell |
I thought Baker only made 6 speed for the tubers and not for the xb's | ||
| Slaughter |
04 bottom end really ought to be upgraded to the 08 since ALL the big end bearings are much larger - ESPECIALLY if you're talking about pumping more poop outta the motor. Since you're going to have the motor apart, it's not a leap of faith BUT the long stroke just doesn't take kindly to hitting the rev limiter and add to that the possibility of stroking and it gets worse. These engines hate hitting the rev limiter at high revs. There are a few folks who can do the work to modify the cases for you and do some flywheel work. | ||
| Rydberg |
fo' sho'. That is the only design flaw of these v-twins is the bottom end takes a beating. Who said the guy would be redline'n 'er though? | ||
| Slaughter |
I figure that he's going to HAVE to change out the flywheels/rods and big end bearings anyways so he OUGHT to do the work to put the 08 flywheels in the beastie. I did on my racebike and she's doing fine after 16 races (so far) - and I DO bounce it off the rev limit on starts every freaking time (and it's rev-limited at 8000) | ||
| Rydberg |
i hear ya. He said it is going to be a daily rider, not a race bike. | ||
| Jstfkndi |
Wow! Thanks for the responses! For the six speed, I think you may be right, I have not seen them for the XB's, but I wasn't sure if I was just missing some other manufacturer options. Really? Put smaller pistons in there? Are they lighter and do I use the same rings as the stock 12's? I have heard a lot about the cams and I think that might be a for sure purchase. The only reason I wanted to experiment is because I will have the other motor stock sitting around, but I do want to make sure that it lasts me a bit though. I have had concerns about the bottom end and whether it would be able to handle the bore increase and maybe whether the clutch should be upgraded as well? Of course the goal is to do this as cheaply as possible and I won't be racing it, but I essentially want a sleeper  Sounds like XB9 pistons and a cam would be a low cost rebuild which I will not complain about. Any power numbers available on the change, or just a rider feeling? Thanks again for all the responses! | ||
| Xl_cheese |
xb9 pistons increase the compression. they are the same diameter as 12 pistons but are domed. I assume the rings are the same. I'm actually going to do this on an engine I'm rebuilding. If anyone can help me out with a part number for the rings I'd appreciate it. I already have the pistons. | ||
| Rydberg |
If a 9 piston has the same diameter, and less total cc's, then it has a shorter stroke right? a domed head is not gonna make up for the 300 cc diffrence between the 9 and the 12. so you would only want to use the domed piston head right? if a 1203 cc comes 10:1 what you will end up with a little less total cc's but higher then 10:1. stop me if i am off please. | ||
| Fast1075 |
The "9" has a 3.125 stroke with a 3.5" bore The 12 has a 3.812 stroke with a 3.5" bore. The deck height is the same...the "12" has .687" shorter rods to allow it to run the same deck as the "9" (or vice-verse depending on your perspective) The shorter stroke "9" has less swept volume due to the shorter stroke, so it needs some dome get the cylinder pressure up...in a manner of speaking..."12" has longer stroke, more swept volume, needs less dome....both engines use the same heads. | ||
| Ducbsa |
Ryd, the cc's will be the same no matter what the CR is. Displacement is the stroke times pi x bore squared / 4 . Dome or flat top doesn't matter. | ||
| Rydberg |
i'm trying to follow you fast1075, so the 12 has a shorter rods but more stroke. so this extra stroke comes from the height of the cam lobes? Ducbsa, the cc's are the total void within the cylinder when the piston is all the way down right? which can be calcd the way you describe. but wouldnt the dome or flat top take away alittle bit of total space? | ||
| Nik |
the cc's are the total void within the cylinder when the piston is all the way down right? which can be calcd the way you describe. but wouldnt the dome or flat top take away alittle bit of total space? The "cc's" is the amount of volume displaced (hence the name displacement) by the piston in the cylinder. So it would be the total void in the cylinder with the piston all the way down, minus the total void with it all the way up; therefore the piston and combustion chamber shape doesn't effect the displacement. The extra stroke comes from the crankshaft, not the cams... I think you need to go take an old engine apart. (Message edited by nik on April 22, 2009) | ||
| Xl_cheese |
The crankshaft determines the stroke. I didn't think there were a difference in rods between the two engines? | ||
| Rydberg |
nik for starters i am no mechanic just trying to get this info straight in my head. You should have called me on it when i said Cam lobes. There is no such thing! i ment crankshaft. so let me get this straight. the only three things that are diffrent are the crank shaft and the piston rods and the domed piston heads. if i took a 9 and just put in a 12 crankshaft or just the piston rod, it would be somewhere inbetween a 9 and 12. but if i change both the crank shaft and the piston rods, it would fully change a 9 into a 12 with more compression then a stock 12? (Message edited by rydberg on April 22, 2009) | ||
| Jraice |
My interpretation of it is either piston will run whatever CC (9 or 12) that the engine was originally, only difference is that the domed piston from the 9 will run a higher compression. Put that in the 12 and you get a 1200cc with higher compression. | ||
| Nik |
There are such thing as cam lobes, but they handle valves not the pistons. I wasn't trying to be negative by the way. I just find it easier to understand things by tearing into them, getting dirty, and seeing what makes them tick. You can only learn so much from reading. | ||
| Fast1075 |
If the pistons are interchangeable except for the dome volume, the longer stroke crank needs rods that are 1/2 the difference in stroke shorter in order for the pistons to be at the proper height at top dead center...both engines have the same bore... The longer stroke/shorter rod crank yields an engine that makes more displacement at the loss of how high it can be revved due to piston speed and rod angle... In either case, it is the crank that makes the difference...short stroke ="9" long stroke ="12" If you put "9" pistons in a "12" you could end up with an engine that don't at all like pump gas....your results may vary...depending on cam selection, timing and fuel maps and how carefully your quench is set up.. (Message edited by fast1075 on April 22, 2009) | ||
| Skinstains |
FWIW, I have a 1050 kit on an 03 9R and it is a nice little bump that you will notice. 1075 is right about the 1/2 rod length as any changes in anything rotational will be double the change due to the change occuring both top and bottom or front and back. The change is from the center. I hope I'm conveying well here. At any rate, "I" would start with the 9 pistons and some (mildly) lumpy cams and see how you like it. It won't break the bank and I'm pretty sure you'll be happy with it. JFSAG...have you ridden a Buell yet ? Stock may be plenty enough fun for you. It is for a lot of people. | ||
| Hurricaneleah |
Antares, check out this link for our Formula 2 engine build details: http://www.trackdaymag.com/ As stated above, there are a myriad of options you can go with. The big bore 3 7/8 bore motors are pretty awesome, its just the cases get a little thin around cylinder studs and can pull out (usually after a few road race seasons). you might be able to get away with it in a street bike. The short stroke motors use big bores as well,and can suffer the same issue, as well as rod big end life...although the 2008 and up crankshaft virtually eliminates that failure mode. Personally i really like the XB12 package described in the article. You can build it out of 100% H-D parts and it has been very reliable/bulletproof. Depending on exhaust/dyno, you are looking at 95-105hp at the wheel with just the Buell race ECM and a nice flat torque curve. Good luck! | ||
| Jstfkndi |
I am going to check out replacing bottom end with 08 crank since that seems to be what might be bulletproof. Not sure what changes they made to them in 08 though. Anyone know where I can get a bottom end that is decent and won't break the bank or just stock form HD? I didn't realize there were so many set ups availble or different ways to go about a rebuild. My issue with the higher compression is that the whole motor is gasketed and I don't want to have to add octane booster (unless I want). I am looking to get a more powerful street performer that will have a decnt motor life. I don't throttle it all the time, but when I do, I want that power to be there. Has anyone had issues with using the 9 pistons and slight cam? Why didn't HD just put those pistons in the XB12? I know that is not a fair question, but if there is an engineering reason for it, then cool, but perhaps they are just cheap! I hope I am not causing too much a stir. I am simplt trying to make the best decision of accumulative info, which I appreciate greatly! Thanks! | ||
| Hogs |
What I have heard is just use the xb9 pistons, and maybe a remap..Cams are good to go stock to keep things Simple...MAy want to use some Better head gaskets... that wd. be about it....! | ||
| Jstfkndi |
That will definitely keep things more simple. Thanks! Any suggestions on better head gaskets\manufacturer? | ||
| Didactic |
Have you looked into an 88" kit? I heard good things about those, and the 1250 kits too. From what I have been told (I am looking into this as well, for when I am ready to bust my warranty) that you have to upgrade a bunch of components so the engine can deal with the power and heat. Good luck and post pictures!  -d | ||
| Macbuell |
Quick question, for someone who will not be doing the work himself, how much will parts and labor for putting 9 Pistons and Cams in an XB12 set you back? Also, what kind of power gain should that get you? This is great stuff. Thanks guys. | ||
| Hogs |
xb 9 cams and xb12 cams are one of the SAME... Better head gaskets would be: http://www.cometic.com/ Not sure of part numbers others here would know. ( http://www.cometic.com/catalogs/harleydavidson.pdf ) (Message edited by hogs on April 23, 2009) |
