Author Topic: Terrible noises and lurching on start up! (Read 3343 times)

coma13 · « **on:** July 28, 2012, 01:14:05 PM »

I've been working on a chopper for several months now, never tore the engine down though.

Went to fire it up today after some electrical gremlins and it happily roared to life. It seemed to be making a lot of engine noise and as I turned the idle screw down to drop the idle to a reasonable level, the engine noise increased (or i could just hear it better over the exhaust) and it popped into gear and died (thankfully). I kicked it to life again, with the clutch in, and the engine noise was reduced but there was still a rattling or tumbling sound coming from the rear of the engine and I could feel the transmission trying ever so slightly to grab sporadically (chain would snap tight and then loosen). I shut it down, broken hearted.

Any thoughts?

coma13 · « **Reply #1 on:** July 28, 2012, 01:16:44 PM »

Before I tore the bike apart, I had an incident with a loud CLUNK sound from the engine and then a lot of rattling/tumbling/chattering sounds, but I was able to ride it home.

I attributed it to my clutch adjuster screw being completely loose allowing the clutch engagement cam to ride out of its detents and rattle around. Now I'm thinking that isn't the case...

coma13 · « **Reply #2 on:** July 28, 2012, 01:33:26 PM »

Also, pushing it back into its corner just now, in neutral, it just popped back into gear, under no load, engine off.

scottly · « **Reply #3 on:** July 28, 2012, 03:27:57 PM »

What year is the motor? '77? Symptoms sound familiar; I'll see if I can find the thread.

scottly · « **Reply #4 on:** July 28, 2012, 03:30:35 PM »

Found it! (the custom google search works pretty well)

http://forums.sohc4.net/index.php?topic=86429.0

coma13 · « **Reply #5 on:** July 28, 2012, 06:26:17 PM »

77K indeed. Damnations! Looks like a case split is inevitable.

scottly · « **Reply #6 on:** July 28, 2012, 07:12:29 PM »

The K7 fuel lid latch I sent you came off the bike that tried to kill me! Hope I didn't jinx your bike.

Before you yank the motor, you might try seeing if you can make it happen, so you know for sure. When it went into gear when you were pushing it, was the bike leaning to the right, or the left?

Spanner 1 · « **Reply #7 on:** July 28, 2012, 07:24:22 PM »

Nothing wrong

... your bike was in a 'false N' that's all, when you started it up.... gear noise etc. normal, then you pushed the bike and it 'popped' into gear... do you have a N light ??
'Chopper', no safety stuff in the wiring to stop the ign. if not in N etc., right ?

scottly · « **Reply #8 on:** July 28, 2012, 09:18:11 PM »

Quote from: Spanner 1 on July 28, 2012, 07:24:22 PM

Nothing wrong ... your bike was in a 'false N' that's all, when you started it up.... gear noise etc. normal, then you pushed the bike and it 'popped' into gear... do you have a N light ??
'Chopper', no safety stuff in the wiring to stop the ign. if not in N etc., right ?

Ray, please read the thread I linked; the problem in the OP's, as well as the problem I had, was due to snap-rings that had popped out of their grooves in the trans.

Spanner 1 · « **Reply #9 on:** July 28, 2012, 09:28:41 PM »

over analyzed, IMO.... we will wait for the OP to report back... looks like bike was between gears... read again...has the bike got a N light, just sayin'?

scottly · « **Reply #10 on:** July 28, 2012, 10:08:24 PM »

Quote from: Spanner 1 on July 28, 2012, 09:28:41 PM

over analyzed, IMO.... we will wait for the OP to report back... looks like bike was between gears... read again...has the bike got a N light, just sayin'?

If a 500 pound bike had fallen on you, due to improperly installed snap-rings, you would not dismiss the reported symptoms so lightly.

coma13 · « **Reply #11 on:** July 28, 2012, 10:32:12 PM »

I am fairly certain I was in neutral, as my usual procedure is to kick the shifter down about ten times and then nudge it up to find neutral. I do not, however, have a neutral light.

As far as the angle when it popped into gear, I don't recall, it was getting rocked back and forth a lot to maneuver around a tight corner.

scottly · « **Reply #12 on:** July 28, 2012, 10:37:33 PM »

Do you have a center-stand? If you do, try propping up the right side with a 2x4, and spin the rear wheel to see if it "self shifts".

coma13 · « **Reply #13 on:** July 28, 2012, 11:38:13 PM »

Kick stand only, but I do have a jack and plenty of milk crates. So I want a lean angle similar to how it would be on the kickstand?

Spanner 1 · « **Reply #14 on:** July 29, 2012, 09:43:24 AM »

Scott, not dismissing your theory at all.... but the poster has not had the motor apart and does not have a N light , as I expected. So, we don't know if the bike was actually in N or a 'false' N between gears

Coma.... connect a 12v test light between battery + and the terminal on the N switch. 'Click' gearshift until light comes on = N. May need to rock back wheel to get the bike to shift. Notice I said 'click' not 'kick' as you describe......

Old Scrambler · « **Reply #15 on:** July 29, 2012, 11:01:15 AM »

Coma..........Both of the 'fixes' are attempting to get to the root of the problem. The Spanner goal is to make sure its just not something simple before you go to the Scotty approach. Don't jump to conclusions....... try one thing at a time.

coma13 · « **Reply #16 on:** July 29, 2012, 11:42:56 AM »

Thanks guys! I will check it out again when I return from camping.

xnoahx · « **Reply #17 on:** July 29, 2012, 01:53:41 PM »

Neutral light only tells you that the bulb works

Spanner 1 · « **Reply #18 on:** July 29, 2012, 02:57:25 PM »

Neutral light will only light when the selector drum in rotated to actual N position and the indent allows the N switch plunger to drop and ground the switch wire.... will not light in any 'false N ' between gears

xnoahx · « **Reply #19 on:** July 29, 2012, 03:03:12 PM »

its a saying, like the only safety a gun needs is a finger

scottly · « **Reply #20 on:** July 29, 2012, 07:16:59 PM »

Quote from: Spanner 1 on July 29, 2012, 09:43:24 AM

Scott, not dismissing your theory at all.... but the poster has not had the motor apart and does not have a N light , as I expected. So, we don't know if the bike was actually in N or a 'false' N between gears
Coma.... connect a 12v test light between battery + and the terminal on the N switch. 'Click' gearshift until light comes on = N. May need to rock back wheel to get the bike to shift. Notice I said 'click' not 'kick' as you describe......

As near as I could tell, my motor had never been out of the frame, much less taken apart. I believe the snap-rings were improperly installed at the factory. I agree about verifying the drum is in the neutral position with the switch; good idea!
Coma, in my case, there were 2 snap-rings that had popped out of the grooves, one on the left side, and one on the right, so it could have possibly gone into a gear leaning either way. In my case, the bike was leaning to the left, on the side-stand. Also, the greater angle you can lean the bike, the better, because it is only gravity that makes the gear slide on the shaft. Be careful; don't drop the bike!!!

scottly · « **Reply #21 on:** July 29, 2012, 07:21:40 PM »

Coma, I just remembered, it was a fuel petcock I sent you, not a latch.

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Author Topic: Terrible noises and lurching on start up! (Read 3343 times)