| Author | Message | ||
     Joojoo |
Hey guys, I've had my 12s for around 10,000KM's now, and its been great. only thing is, that I sometimes have a hard time dropping down into 1st....it feels like Im in first, but Im actually in 2nd...if I let the clutck out a bit, and then pull it back in, no probs, she dropps into 1st nicely....NO BIG DEAL, I can live with the Buell gearboxes... Thing is, yesterday I thought I was in 1st, and I was in 2nd, and started to take off...being in 2nd, the bike pinged for a couple seconds (low RPM's in 2nd) before I grabbed the clutch back in and dropped into 1st for a proper takeoff. Motor seemed fine after the pinging crap. I know that the pinging is the sound of the piston heads hitting the side of the walls (from what my mechanic told me)....my question is: are these little incidents going to cause damage to my pistons? walls? heads? rings? Screw anything up inside the motor? If it is, I'll be intese-careful not to let this crap happen again....actually, Ill try anyway, but Ill get stupid about it if its gonna affect the long-term life my my engine.... Any thoughts would be appreciated.. Tanx, Jack | ||
| Geoffg |
I know that the pinging is the sound of the piston heads hitting the side of the walls (from what my mechanic told me) That's a new one on me. I always thought pinging had to do with slight pre-ignition... Unless it's severe and long-term, pinging should not hurt your engine.} | ||
| Whodom |
Pinging is caused when two flame fronts "collide" inside a cylinder. One flame front is supposed to be there, ignited by the spark plug. The other flame front isn't supposed to be there- it's ignited by some little hot spot in the cylinder head (a sharp edge, a fleck of carbon, etc.). The flame front from the spark plug creates a pressure wave in front of it and under just the right conditions a little hot spot ignites the fuel/air mixture at the other end of the combustion chamber. When the two flame fronts collide, it makes the ping noise you hear. This happens when you're lugging the engine because the cylinder pressures are highest at low RPM & large throttle opening. Occasional minor pinging at low RPM doesn't hurt anything- in fact, it tells you the ignition timing, compression and fuel mixture are right at the limit for maximum performance- just where you want them. | ||
| Geoffg |
Yep--that's exactly what I was given to understand. You can sometimes "cure" pinging by using a higher octane fuel (less easily ignited, therefore less likely to be ignited by something other than the spark plug). | ||
| Static |
Geoffg is right, the sound you heard was pinging (or pre-ignition) and not "piston wrap" ( the condition your mechanic mentioned). Pinging can and will often happen in high load low rpm conditions like leaving a stop in 2nd gear. It's doubtful you caused any damage but if done repeatedly sustained damage may occur. Try not to lug the motor if you can. I had a similar shifting problem with my xb9r(. I found that there was too much fluid in the primary. I checked spec 1qt(sorry you will have to do the conversion) for the trans. I drained almost 1.5 qts from the primary. hope this helps. | ||
| Ftd |
Preignition: When the fuel air mixtures ignites BEFORE the spark plug fires. Caused by glowing carbon pieces, spark plug of wrong heat range, or extreme overheating. Detonation (knocking): The spontaneous ignition of the ENTIRE charge in the cylinder instead of the normal smooth flame front traveling from the spark plug to the opposite side of the cylinder. Detonation is caused by the extreme pressure rise in the cylinder that occurs when the charge is first ignited. Detonation (knock) = bad Preignition = BAD | ||
| Joojoo |
Thanks for the info guys.... Static - "It's doubtful you caused any damage but if done repeatedly sustained damage may occur." - What type of damage? what gets busted??? Jack (Message edited by joojoo on August 22, 2004) | ||
| Geoffg |
Joo, severe detonation can blow a hole the size of a quarter through your piston crown. However, the pinging you experienced is a relatively mild form of pre-ignition, and it's 99.9% certain that no damage was done at all. My wife's car pings every time we go up a steep hill--no problem, and really nothing to worry about. We just shift down one and it goes away... | ||
| Static |
Again geofg has beat me to the answer, but in engines that have seen prolonged pinging you can begin flake the aluminum off of the piston and weaken the piston crown. I really can't explain much beyond that, though I have had this happen on my own vehicle. Actually just about every vehicle ( gasoline powered ) pings, but there are sensors that help the ecm retard the timing accordingly. | ||
| Hootowl |
Detonation is destructive because the explosion within the chamber is violent enough to scour the air/oil barrier off of the piston face and cylinder walls. The metal bits are then directly exposed to the combustion heat. Let the piston holing begin. | ||
| Joojoo |
Dont the metal bits from the explosion get washed away with fresh oil within a second after the detonation occurs and then taken out by the oil filter? Jack (Message edited by joojoo on August 23, 2004) | ||
| Captainkirk |
Sure...and the oil washes them past the rings and piston skirt on the way out (ouch)  | ||
| Static |
not a whole lot of washing going on topside of the piston crown.( unless you've just created a large diameter, pressure relief hole in the piston) just flakes of metal scaring cylinder walls and clinging to anything hot enough. Not very pretty though. | ||
| Joojoo |
Crap. I hope I didnt do any of that stuff to the top of my piston when I pinged her starting in 2nd....oh well. That sucks. Jack | ||
| Fullpower |
i have been running my XB on 87 octane lately, a ducati mechanic said the wifes monster would actually prefer regular, so we have been filling both bikes up at the 87 hose for a few weeks now. no problems to report. | ||
| Bomber |
JooJoo -- no worries, bud -- the small amount of "abuse' yhour engine sustained won't casue any damage . . . . Full -- a buddy reported the same on HIS monster (that is, High Test caused it to run badly), so he switched to 87 octane and ran happily on that -- his S3, on the other hand, objected strenuously to that diet -- I've no idea how an XB seires mill will react to 87 octane -- keep us all posted, please | ||
| Fullpower |
it seems that the XB heads have a real good swirl or squish or whatever, they burn very efficiently, and dont have a real bad octane dependence. my sportster with flat top pistons barely runs on 90 octane, with significant pinging under hard accel, needs methanol mixed into gasoline to really get it on, whereas the XB runs on regular even on hot days, and doesnt even ping in heavy traffic. any body measure the cranking pressure on an XB12 yet? i just had my spark plugs out yesterday, but did not think to check pressure. | ||
| Unibear12r |
My XB12 absolutely HATED the 87 octane (nothing else aval.) I put in it in Death Valley. 111 degrees at 10am and we had been riding hard sense dawn. Until the next tank fill it was all about what gear & throttle position I needed to keep it from pinging. If I'm unsure of my fuel stops in the future I'll be carrying booster. |
