| Author | Message | ||
     Reepicheep |
I pulled apart my 05 XB9SX to replace the oil pump pinion gear (which turns out to have been worn, but not really that bad). When I pulled it apart, the cams came off with the cover, and I was trying to use the "front rocker box off, rear at TDC" trick, so the cam timing mark alignment would not have been meaningfull anyway... I didn't bother to even look at them, I just figured I'll just time the cams when it comes time to reassemble anyway. I screwed up the "don't remove rear rocker box" thing by letting the cams come out, but it turns out that may have been a blessing in disguise. Look at the following picture... You can't really see the stamped V's in the big cam, trust me that they are correctly aligned (they are).  Now look at the white paint mark on the gear on the crank that drives the cams. When I align and time everything right, it is off by a tooth. I have to assume that mark was put on when the bike was manufactured, and it was clearly done after the cam was put in place, and it was clearly off by one tooth. So how did this thing ever run so well? That's gotta be close to two degrees off, and it would have put all four cams out of sync with the crank (and crank position sensor). The bike was dyno'd when it was fairly new, and made an honest 73RWHP or so, which is spot on for a 9. It pinged if I didn't put in good gas, but then so did my M2. Though the Uly seems a lot less sensitive. Maybe the cams were aligned right when it was put together, but why would they put in that gear, put a paint mark on it, take it back off, then put it back on right? That makes no sense. It's a mystery... Any experts know what an XB9 would run like with that cam one tooth off like shown in the picture? (Message edited by reepicheep on May 06, 2010) | ||
| Reepicheep |
Correction, counting the teeth on the crank gear, and doing the math, that looks like the timing was 4 degrees off.  I wouldn't think the thing would even run... | ||
| Kilroy |
I don't think cam #3 would have been able to line up if the crank drive gear was off by a tooth | ||
| Id073897 |
The cams are spot on. RTFSM. | ||
| Reepicheep |
Thanks for the confirmation! I'm positive the cams (as pictured) were lined up as per TFSM. That's how I got them lined up.  I guess my big question is the nagging unknown. One of two things happened... 1) The cams were misaligned at the factory, and ran that way (4 degrees off) for 30k miles without any noticable issues beyond perhaps slight oil consumption and a propensity to ping on lower grade gas. 2) The factory put the crank gear on, put the cam on, slapped a stripe of white paint on it to mark alignment, then took it back off, reassembled the cams correctly timed, then reassembled the motorcycle. Both seem unlikely. Will an XB9 even run with the timing 4 degrees off? | ||
| Reepicheep |
Interesting... not Buell specific, but based on some googling, on other 4 stroke motors (i.e. Miata and Integra), advancing the timing 4 degrees is fairly commonly used to get a little more power, but risks pinging. Which this bike was prone to do. I always ran the highest octane I could find, (in 30k miles, this bike never had anything less then 92 octane) and when I did occasionally hear the bike pinging, I just backed off the throttle. It wasn't a big deal. I guess we will find out. It's bolted back together now, and the motor turns over fine by hand. Hopefully it runs well now (even if it makes a shade less power) but is less fussy about gas and hot days. I wonder if they did this on purpose at the factory for the XB9SX's to get a little more pop out of the engine? This was a very low VIN (like #63, which doesn't mean it was the 63 9sx made, but does mean it is an early one). | ||
| Id073897 |
According to some white marks both my bikes had timing advanced about 180 degrees. Most fortunately just riding sorted things out, exactly as it had to be. Never had to care about that. That's great, isn't it? | ||
| Reepicheep |
Thanks Gunter, that is very helpful. So for reasons unknown, HD paints white stripes on crank gear and driven cam gear that have no bearing to properly timed cams. Probably right after they sacrifice a chicken, and before they whack the milling machine with a 50 year old oak 2x4 where the red X is marked... they don't know why they do it either, but if they don't do it, the engines come out wrong... I can live with the mystery...  | ||
| Sparky |
That appears to be evidence that Harley deliberately tried to sabotage Buell by providing engines that would tend to self-destruct if not ridden at a Harley's pace (slow).  | ||
| Livers |
The white mark I suspect is to show a matched pair of cam and pinion gear for tolerance purposes. |
