Another "knocking" question - searched-help

[Awall]

Guy's

I've spent 2 days searching (detailed as possible) about engine knocking. Long description...but want all the details out so as not to wait your time. Thanks in advance for your consideration and suggestions.

1983 GS1100L "Nimrod project" 43,000miles - Vance and Hines 4-1, carbs rebuild recently, new plugs and wires and new oil change. Haven't done a shim job yet, don't know the jetting in it. Stock airbox and filter.

Two days ago she developed a loud rythmic knocking that sounds like it's coming from left side and lower than heads. Didn't have it a month ago when I purchased and rode the bike for a couple of days. I can feel it in foot pegs and does it in all gears. I've searched and found many who have rattles and knocks at idle and startup...but mine is like a small sledge beating from within and only happens during load. It sounds as if it got alittle louder today over the way it sounded yesterday. When I pull the clutch in, it's gone, but as soon as i let the clutch out and throttle it comes back and doesn't stop. It doesn't knock in neutral during starting. I was going to take it in for a carb sync this week because it was popping and farting quite a bit. I sealed the airbox today with new weather stripping, checked to make sure snorkle and stock air filter were secure and sealed while in it's cradle. Checked that all airbox boots were clamped tight and seated. I have rubber that has come off the rusted flange part on the intake boots and noticed a few weathed cracking on outside. I know they need repalced. After sealing the box and checking exaust bolts I almost eliminated the backfiring lean condition. Aside from the possability of air leaks from boots....and carbs out of sync...

Do you feel this knocking could be a clutch nut or starter clutch loosening...or something else?

I'm going to start tearing it apart to diagnose further but wondered where to start and in what order. Hoping it was just a clutch nut and was going to start there. any direction?

[Big T]

It's really hard to say, since you haven't narrowed down which side the noise is coming from

But, you have chosen the right 2 candidates - starter clutch and clutch

If you squeeze the clutch lever, does it go away?

You're not too clear on that point. If that's the case, pull the clutch cover and go for it. It may just be loose.


BTW, you're just tossing money away if you sync the carbs now. Get new intake boots, adjust the valves and then sync - because you'll have to resync afterwards, anyway

[posplayr]

clutch clatter and many of the normal knocks and clicks go away with RPM. If it increases then sounds like a rod or at least something more serious.

I would make sure that

a.) it is not the clutch
b.) nothing under the valve cover
c.) nothing under the stator side cover

(in that order)

If it is still there it is likely serious

PS Sorry to hear about that; wonder if the PO has some STP in the oil to pawn it off

[Awall]

Yes , it does go away when clutch is pulled in and doesn't knock even when I rev it with clutch pulled in. That's why my mind goes to the clutch area. Wouldn't a rod alway knock even when engine revs with clutch pulled in?


I figured that would be the case with the sync..thanks for the suggestion.

Thanks for your quick responses.

[BassCliff]

Hi,

If it is the clutch, your clutch is on the right side of the bike (as you are sitting on it). You may only need new clutch springs. You may need to smooth out any grooves in the clutch basket splines caused by rattling clutch plates. See the Clutch Odds and Ends on my little website for pictures (thank you Mr. bonanzadave).

It would worry me, though, if the knocking is present throughout all the rev range.


Thank you for your indulgence,

BassCliff

[Awall]

The best i can hear with my helmet on..riding the bike is that it was more on left side. I could be wrong..and have been known to be wrong alot.

[BassCliff]

The best i can hear with my helmet on..riding the bike is that it was more on left side. I could be wrong..and have been known to be wrong alot.

Hi,

The stator, starter, and starter clutch are on the left side. Let's hope it's not a cam, valve, or rod, etc.


Thank you for your indulgence,

BassCliff

[Big T]

Yes , it does go away when clutch is pulled in and doesn't knock even when I rev it with clutch pulled in. That's why my mind goes to the clutch area.

Wouldn't a rod alway knock even when engine revs with clutch pulled in?

Yes, a rod would always knock

So, pull the clutch cover and see what you find,

Could be a simple as a loose hub nut

[Awall]

I thought so. whew!
I'm going to tear into it tomorrow. I'm thinking starter clutch or clutch nut.

[Graham]

When you do pull the clutch, check the springs on the back of the clutch basket. Lost 3 on my 83 GS1100GL found 2 springs in the pan and a lost tooth from the starter gear. They can breakup with age.

[Nessism]

A loose clutch hub nut is common too. Not sure if the noise would go away though with the clutch pulled in though.

[Awall]

Clutch tore apart and found the clutch nut was a hair loose but not backed off. I tightened it. Everything else looks good in there. Glad I checked to get it all squared and have peice of mind.

But I don't beleive that is the problem.
Looked at the starter clutch and bolts are tight. Good to go.

Now brings me to where I think the problem is...The u-joint!!!

I moved the shaft boot and found one of four blots missing ahead of the joint. I can move the joint up and down in the shaft tube/swing arm with my finger more than what I think I should be able. It has alot of play. Also the movement seems to continue on into the secondary gear box at the back of the motor. I think I might have that bevel gear problem.

Need to get it all torn apart.

[Awall]

FOUND THE PROBLEM!!!!

PO appears to have done the beveled gear shaft repair and the bolt had backed out. It messed up some of the last lines of threads on the bolt just under the head. The universal joint (4 bolt mounting plate that the nut holds in place) splines are toast. I didn't see an sign of loctite on the bolt so this might be the reason for the malfunction. I also noticed one of the mounting plate bolts was gone and the other 3 bolt heads were pretty messed up. The loose bolt must have done that damage.

Pushing up on a loose u-joint plate


CAN I BUY JUST THIS PART? CAN IT BE REPAIRED? Splines are toast. Bolt needs replaced.


So shopping list :
Used universal joint mounting plate (called Suzuki and they cannot get the part)
New boot
High strength loctite
4 New bolts for mounting plate.
1 New high tensile allen bolt for spline gear
Grease

Thanks again for everyones help. The knocking sound was coming from a loose u-joint clanking in the drive shaft tube. Man I love finding the cause of a problem. At least it wasn't a rod! Gave me an excuss to check everything over and learn how to remove thw swingarm.

[BassCliff]

Hi,

Have a look at this article from Mr. Zooks and see if it give you any ideas.

Bevel Gear Shaft Repair
(by Mr. Zooks)

But it definitely looks like you need #11 in the fiche page below, part# 24951-49100, Universal Joint Flange:



You best hope(s) are the Parts For Sale section here in the forum or Ebay. Here is a list of other bikes that use this part#:

• 1981 SUZUKI GS650GLX - SECONDARY DRIVE GEAR
• 1981 SUZUKI GS650GX - SECONDARY DRIVE GEAR
• 1982 GS1100G - SECONDARY DRIVE GEAR
• 1982 SUZUKI GS1100GKZ (Touring) - SECONDARY DRIVE GEAR
• 1982 SUZUKI GS1100GLZ - SECONDARY DRIVE GEAR
• 1982 SUZUKI GS650GLZ - SECONDARY DRIVE GEAR
• 1982 SUZUKI GS650GZ - SECONDARY DRIVE GEAR
• 1982 SUZUKI GS850GLZ - GEAR SHIFTING
• 1982 SUZUKI GS850GLZ - SECONDARY DRIVE GEAR
• 1982 SUZUKI GS850GZ - SECONDARY DRIVE GEAR
• 1983 SUZUKI GS1100GD - SECONDARY DRIVE GEAR
• 1983 SUZUKI GS1100GKD - SECONDARY DRIVE GEAR
• 1983 SUZUKI GS1100GLD - SECONDARY DRIVE GEAR
• 1983 SUZUKI GS650GD - SECONDARY DRIVE GEAR
• 1983 SUZUKI GS650GLD - SECONDARY DRIVE GEAR
• 1983 SUZUKI GS650MD - SECONDARY DRIVE GEAR
• 1983 SUZUKI GS850GD - SECONDARY DRIVE GEAR
• 1983 SUZUKI GS850GLD - GEAR SHIFTING
• 1983 SUZUKI GS850GLD - SECONDARY DRIVE GEAR
• 1984 SUZUKI GS1100GKE Touring - SECONDARY DRIVE GEAR

If necessary, it looks like #1 in the fiche above may still be available ($225 at partshark.com), but I don't know if they mean the drive gear or the driven gear.
EDIT: Just double-checked the part numbers. It looks like the bottom gear, the "secondary drive gear" is still around, but not the top "driven bevel gear".

Good luck to you. I'm sure a resourceful guy like yourself will have little trouble. Keep us informed.


Thank you for your indulgence,

BassCliff

[Awall]

Thanks Basscliff,

Your "how to" was what I looked at before I tore things apart. Thanks again for the wealth of information.

I lucked across a Universal Joint Flange from an 82 650gl on Ebay tonight. Bought it for $9.99 plus shipping of $6.99. Only one on there...man I was lucky.