popping/clunking sound

[snapon]

1999- 60,000 miles on the clock. Jump on it to go for a ride Saturday get 100 feet from home and start hearing a loud popping sound from under the bike. Appears to be coming from the clutch/transmission area and forget about trying to accelerate noise just gets worse. No sounds or symptoms at all leading up to this. Bike is adult owned and never ridden hard no burnouts wheelies and very few what I would call hard accelerations. (This bike is ridden 2-3 times a week to commute to work and on the weekends). Any help or suggestions would be appreciated before I tear into it. Because let's face it I don't know what I'm looking for. 

[Dorkman]

Think you need to provide more info.  Popping like exhaust, metalic noise, regular interval, thunk-thunk, going through gears or just in first, clutch rough, at idle too...that kind of stuff.

[Denny47]

Go to the search box at center right of page. enter:  clunking noise    lots of threads on this, you can find a lot of good info here from past threads on almost any questions you have, will keep you busy for awhile

[YoungPUP]

Take a look at the u-joint.  Then the splines at the pinion cup and drive flange.

[Michvalk]

Take a look at the u-joint.  Then the splines at the pinion cup and drive flange.

+1

[snapon]

Sorry not enough info. Popping/clunking noise (sounds like gears engaging and disengaging) is in I'm assuming all gears although I did not try to go past 2nd because of the noise. No noise while in neutral  It is not u-joint, exhaust or rear bearing related I am familiar with all of those noises and those items have been checked (the noise is coming from under the bike-clutch /transmission area), the noise is consistent while trying to accelerate clutch feels firm bike will engage into and out of gear without a problem. I have already done a search and although there is a lot of good information under that description I could not find anything related to this particular problem.

[Chrisj CMA]

Sorry not enough info. Popping/clunking noise (sounds like gears engaging and disengaging) is in I'm assuming all gears although I did not try to go past 2nd because of the noise. No noise while in neutral  It is not u-joint, exhaust or rear bearing related I am familiar with all of those noises and those items have been checked (the noise is coming from under the bike-clutch /transmission area), the noise is consistent while trying to accelerate clutch feels firm bike will engage into and out of gear without a problem. I have already done a search and although there is a lot of good information under that description I could not find anything related to this particular problem.

Pull the entire drive train......including U-joint and the problem should be obvious.  I vote for the pinion cup splines.  when was the last time the Pinion cup was serviced?