| Author | Message | ||
     Haaken |
Inwas cruising Craigslist and saw someone that has a wrecked xb12 for sale stating that it has a certification of destruction, so no fixing that it would seem. If I could get a good deal would it be worth to swap over the entire top end onto my x1? What kind of power boost would I be looking at using the pistons if they are in good shape still in either my cylinders of the xb cylinders? | ||
| Oldog |
not much in peak and not much in over all. IIRC late model XB 1200s were like 103 hp | ||
| Hybridmomentspass |
considering the FI models were rated at 101...thats 2hp. two horsepower for all that work. nah, not worth it | ||
| Haaken |
I was under the impression that the XB heads would make a difference since they flow better. | ||
| Natexlh1000 |
The big difference is the valve stems are thinner on the XB so that the port has more cross sectional surface area. Also, they have improved beehive springs so they can be revved faster before floating. This doesn't really matter in the 1200cc engines but the XB9 engine revs a lot more due to its shorter stroke. Short answer: If your stock heads are toast and you need heads anyways, maybe it's worth it. otherwise? nope. | ||
| Haaken |
maybe what my reading was referring to was after 1250 kit and so on since all of my reading points to going XB heads once you go to a 1250. I thought maybe It would help at least. | ||
| Natexlh1000 |
I think the real advantage in the 1250 kit is the nikasil(or something) liners instead of cast Iron sleeves. Engine runs cooler and therefore better. Here's some fun info: XB9 and XB12 engines have the same bore with different strokes. People have been able to play games with that; cranking up the compression ratios, making oversquare 1100cc engines, you know the fun stuff  I understand the urge to improve and whittle away at an engine. Personally, I have a low faith in my own abilities. (I'm chicken in other words) | ||
| Robertb1958 |
The XB12 heads are supposed to flow a little better than the Thunderstorms. You would need the XB12 pistons to match up, not supposed to mix/match heads and pistons. Without cams, more RPM's, free exhaust, and maybe a more open throttle body, doubt there is much real world difference between the X1 piston/head setup and XB12, especially at 3-5KRPM | ||
| Haaken |
My thought was to pick up the swrecked xb and maybe rebuild it, but most likely use the heads for a 1250 build down the road and then use my existing top end to swap over to a sporty for a cafe build. I am picking up a '72 shovelhead hard tail bobber my dad and I built, so not really going to have money for another build anytime soon, lol. | ||
| Stev0 |
If you get the XB top end freshened up when you change over you should gain a bit. You will need to change the whole thing as the earlier pistons are domed and the XB's are flat(ish, they have a small raised section in the middle). If you put bigger cams with more overlap and an exhaust on it that will take advantage of that extra overlap you can see decent gains at a particular rev range, usually at the top. If you only use it on the street, don't spend much time at the rev limiter and don't play down the strip, then save your money and go on a holiday instead... While it sounds like a great idea, unless yours actually NEEDS a freshen up I wouldn't worry about it. (and that's from someone who has about a dozen sets of sporty,tuber and XB heads on his shelf) | ||
| Ratbuell |
Don't forget you'll also need a new front motor mount, to go with the XB heads. Steve0 - don't have a good front thunderstorm head collecting dust, do you? Just need stock...I have an S3 Defender project that has a busted front motor mount and head. | ||
| Stev0 |
I had to swap one out on the S3/X1 the other day as the exhaust stud is broken off deep inside with an easyout in it.. I think that's my only "spare". I'll have a look later tho as I seem to recall I have a front head that has broken the mount off as well. (could be a little while until I get to it tho as I'm in the process of moving house, which includes my workshop stuff) You can weld that piece back on, seen it done a few times. Has yours just broken the mount piece off or more damage ?? | ||
| Ratbuell |
Far as I can tell, the boss where the mount bolts is snapped off. I was going to put new mount bolts in it right after I got it because I thought that was the issue...then found the busted head and parked the bike to deal with other projects for now. | ||
| Stev0 |
Yeah, I've got one the same. The boss on the head where the bolt goes in breaks off. They can be welded back on without and drama. Just use a mount to get the spacing and angle right and then clean the weld up with a grinder/flapper wheel, repaint and you're all good. |
