Topic: "BONG" when shifting or hitting bumps

[2tall]

Hey all, I've got a weird one for ya.

About 2 months ago, I started noticing a soft "bong" from my front end when hitting bumps. Not all the time, and not exactly consistent. I checked the usual suspects (front brakes, horn mounts, etc) and everything is snug and adjusted properly. I figured it was "one of those things" that these bikes just did.

Then, about a week ago, I noted the same exact noise when shifting in 2,3 and 4. Not all the time, but maybe 80% of shifts. It also makes this noise on bumps, and more frequently.

Other things that started at about the same time (a week or so ago) was a little more mechanical noise from the gear box upon low rpm (2,000) roll outs in 1st or 2nd.  The noise itself isn't really a grinding or horrible noise; rather just an increase in mechanical noise. The "bong" noise comes from the shift location, but this mechanical noise is definitely from the rear area of the transmission; maybe even right at the sprocket area. I think the chain is fine, but I haven't lubed it in about 3 months/800 miles. (fair weather riding only)

Also, the oil is 1/2 between the lines. I plan on topping it off this weekend after I get my check... Any ideas?

Thanks!

Paul

[michrobi]

Hard to say without actually hearing it, but I know the center shift fork that holds on to the main shaft is similar to a tuning fork. I guess if something was hanging on to one of those forks when it shifted it might bong when it let go. A total blind recon though.

[michrobi]

What bike?

[the technological J]

pull the chain cover case u might get lucky and find something in there.... u dont have to drain the oil to do so either
 when shifting does the noise happen at the shift or at the time u release the clutch?..... and i would put some lucus oil treatment in it..... but thats me check around to see if its bad for this situation

[the technological J]

possibly clear up some of the noise... probly not the bong

[dave500]

with the clutch cover off,check the end float of the entire basket,it might need another shim behind the circlip.if your prepared to do the clutch id drop the pan aswell its not hard,you can have a gander in the gear area then aswell as desludge the pan,always a satisfying procedure.

[TwoTired]

Haven't read but the first post.  But, check your drive chain tension.  It might be so loose that is is smacking the chain guard.

[paulages]

I've never heard of "shifting" or "bumps"... is this new marijuana lingo? 

[TwoTired]

Before you rip the motor apart thinking the worst, check your drive chain for tension and uneven wear (stretching).  If it can hit the chain guard while parked, it can do so while driving, too.

Edit: spelling and fumble fingers. 

[fastbroshi]

   I can attest to it being the chain out of it's place.  I got back from a good 300 mile ride a while back and the next day while farting around the neighborhood I was hearing it too.   So I get back to the house and it's the first thing I noticed.  And the symptoms are just like yours.  It can sound like it's in the front end.  Mine was making that sound and I have a plastic chain guard, so I guess it hits the cover over the front sprocket.

[B.O.X.N.I.F.E.]

Primary chain?

[fastbroshi]

I don't believe that's the correct name, I think the primary is the one that connect the crank to the tranny(smission, get ur mind outta the gutter  ), and the drive chain being the one connecting the sprockets together.

[B.O.X.N.I.F.E.]

I don't believe that's the correct name, I think the primary is the one that connect the crank to the tranny(smission, get ur mind outta the gutter  ), and the drive chain being the one connecting the sprockets together.

Primary chain stretching can cause the chain to contact the inside of your cases. Early on it sounds like you're describing. Later on it wears a hole in the case and you lose oil pressure. 13k is low mileage, maybe the bike has been ragged on and never had the carbs sync'd?

[Spanner 1]

I'm +1 with the drive chain camp, except 'bong' off the mainstand rather than the chainguard......can happen over a bump or when you let off the throttle and it mysteriously sounds like something wrong in the frontend/wheel, at least did for me...! until I figured it out.

[bistromath]

Drive chain should be adjusted every 150-200 miles, not every 1500. Check that tension.

[Industrial Cafe]

strange problem, I think a video would be super helpful.

maybe chocked up on the center stand?

[Industrial Cafe]

it's worth a shot.

[TwoTired]

Again, thanks for the pointers. I just wanted to clarify that the noise happens at the exact time of the shift.

Shifting puts a shock on the chain, making it whip about.

Not when I engage or release the clutch.

It's a wet clutch and there is always some viscous engagement if not outright dragging clutch due to mis-adjustment and warped plates.

In other words, along with the mechanical "click" of the gear change is this noise at the exact same time. It should also be noted that it makes this noise while standing still. (Like shifting from neutral to 1st). At least you guys are pointing to the outside and not the inside.  

You mean like when the chain is shocked changing gears?

Look, this will be my last suggestion for you as you seem determined to take the motor apart.  Have fun with that.
Is it sooo hard to put the bike on the center stand an try to touch the chain mid point to the guard while slowly turning the rear wheel?

I adjusted the drive chain about 1500 miles ago,

Did it make the dreaded noise 1500 miles ago?  Has your chain ever gotten dry?  Ride in the rain?  Is it well lubed?  How do you know it is still in adjustment?

but I haven't checked the primary chain since I got the bike a year ago. I'll do that this weekend. What things should I look for if there isn't any obvious wear when I look at the primary?

Good luck with your investigative surgery!  Might as well do a full rebuild while you're in there!  Come on, that's what you really want to do, after all.  

If it helps, I have a 74 CB550 that would go bong, usually during downshifts, or putting the bike in gear.  The drive chain had stretched irregularly, leaving "tight spots".  Actually, some of the rollers had split and fallen off.  New chain no bong.

[TwoTired]

Again, what leads you to believe I am looking internally?

What things should I look for if there isn't any obvious wear when I look at the primary?

FYI, the primary chain is INSIDE the engine cases.  Making it an internal problem/suspicion/investigation.  You'll have to at least drop the pan to look at it, and pull the engine, split the cases, to replace it.

Do what you want.  I won't annoy you with any further posting in this thread.  It'll save me a lot of frustration, I'm sure.

[B.O.X.N.I.F.E.]

I'm the one that mentioned the primary, because that's what my problem was on a fairly low milage engine (17k). I didn't see that he hadn't adjusted his drive in 1,500 miles, or that he hadn't checked for stand or guard contact of the chain yet, as suggested.

If you haven't done that or adjusted it in 1,500 miles that's almost certainly your problem.

[Henning]

You need to get to know your chain. My crappy non o-ring David Silver Spares (grrrr) chain desperately needed adjustment after just 600 miles. My new and much much better o-ring chain hasen't needed adjustment after 2000 miles.

[B.O.X.N.I.F.E.]

You need to get to know your chain. My crappy non o-ring David Silver Spares (grrrr) chain desperately needed adjustment after just 600 miles. My new and much much better o-ring chain hasen't needed adjustment after 2000 miles.

He's on a 550. O-ring chain will eat a hole in his cases.

[Henning]

The point is, chain wear varies a lot, depending on what quality chain you have. It doesn't seem like our punter (2tall) has any idea of how often he needs to check the chain. Skill levels on this forum are wildly different, not that that is a problem.

[Industrial Cafe]

Drive chain should be adjusted every 150-200 miles, not every 1500. Check that tension.

I didn't know that.
 I have a HUGE X-Ring chain that hasn't needed to be adjusted yet.

I swear all the links are safety links.
that would be a funny chain
 

[mystic_1]

Is this amount of play too loose?

Follow the specification in your workshop manual.  If you don't have one, either buy one or download one from the following location:

http://forums.sohc4.net/index.php?topic=17788.0

mystic_1