rolling knocking - big end?

[Anonymous]

Afternoon all,

I wonder if I might call on your experience...

I have a 1982 GS1100G which while being the best bike I've ever owned is also breaking my heart at the moment.

For as long as I've owned this bike (3 years) it has had a rolling knocking noise coming from the engine. I have had the rocker cover off many times and never noticed any problems. This used to come and go but now a days is there constantly.

In the last few weeks I got the bike Stage 1 Dyno Jetted, as not so long ago I put a Vance & Hines 4-1 on it (+ stock replacement K&N). Since doing this the rolling knocking sound has got MUCH worse. So bad that I can't really ignore it anymore. I can't really pin down where its coming from, as it can be heard both from the top and bottom of the engine. It was recently suggested that it could be the big end bearing, which is why I'm sending this mail - I'd really like to rule this out.

I'm told by the local mechanic that the carbs are balanced, I can't verify this for a week or so (vacuum guage is on order). However the noise completely disappears when you rev over 2500rpm!

I'd really appreciate any advice you can spare. If there is a way anyone knows of checking the big end without having to split the engine it would be great!!

One other little question - I have on occasion found my battery bubbling after a spin. Is this common?

Thanks for your help!

- RK

[redliner1973]

Sounds by what your describing as a timing chain. check the tensioner. As for the battery, it is normal for them to 'bubble' when charging, best be it to get voltage readings at the battery when engine is running. :twisted:

[Anonymous]

Thanks for the reply.

I'm pretty familiar with the sound of a loose / bad chain, this is quite different unfortunately.

Reading some of the engine Q&A's, it sounds like the "typical GS rattle" people describe. Only this doesn't stop until 2500rpm (unlike most people quoting circa 1500rpm). Also engine temperature makes no difference. Its exact same hot as cold (

- RK

[SqDancerLynn1]

Just a guess? I would check the stator magnet to see if it has come loose?? Also check the cam chain. Both are Easy to do and eliminate them as a problem Engine noises are hard to diagnose over a computer and the GS motors are noisey even when running properly

[saaz]

Stator magnet is one possibility well worth checking. If you want to test for a main bearing, usually lugging the motor in a high gear at very low revs will reveal a big end bearing...it will knock like crazy. The noise may go away at higher revs. The small end bearing will make a noise all the time.

[Paul]

Just a guess, I wouldn't think that it was a big-end because it probably would be outside the cases after 3 years!
It could be clutch rattle, caused by the rivets in the back plate wearing, or side play on the camshafts.
If its the clutch its relatively easy to fix, and if its the cams don't worry about it - some GS's do it, some don't.

[Anonymous]

The stator doesn't have a magnet. The magnet is in the rotor.

Also check the starter clutch has not come loose from the back of the rotor. I had this happen to me once and I could have sworn it was a big end. It matched your description perfectly.

[Anonymous]

Thanks for all the suggestions guys. I have a new EBC clutch kit here which I'm going to fit in the next couple of days and check for all the things suggested above.

The guy doing this work with me (who knows significantly more about engines than I do) is also planning to "file the clutch basket"?!? The bike is incredibly hard to get in to neutral. So apparently this will solve the problem. I'm mentioning it here purely because I have never heard if it before.

- RK

[redliner1973]

what he means by that is to file smooth the slots where the clutch plate/driven plates are. After use for awhile, sometimes the drive plates, made of steel, will 'beat into' the softer clutch housing. weather this works or not I am not sure, as I have never had to do it. mine looks OK, but have heard of it being done. :twisted:

[jimcor]

Another possibility is the starter clutch. That's not a big end bearing you're hearing. No way you would have run it for 3 years! :?

[Anonymous]

Two thoughts.

I used to use Barnett clutch plates until I realized they are so thin they cut little notches into the clutch basket. These notches were pretty deep. With the clutch pulled in things were pretty quiet but when I let the clutch out, it started banging around baddly. I don't know what EBC plates look like but the stock plates I use now have thicker edges and don't chew up the basket nearly as much.

You could feel for excess play in your con rods by doing the following:
When the engine is cold (has sat over night), take out the spark plugs and get a longish wooden dowel that will fit through the spark plug holes. Get a flashlight and watch piston 4 come to top dead center. Keep turning the engine until you just see the piston start to go down. Now use your dowel to push down on the piston. You should feel no play or maybe just a tiny bit of play. Repeat for each piston. If all the pistons seem about the same, no worries. If one has more play than the rest...

[Anonymous]

Heres a little update anyway...

Yesterday I did the balancing. Cyls 1-2-3 were all the exact same. 4 was quite a bit out. So I adjusted it and they are all the same now. Although it didn't make any difference to the knocking.

Tonight I started the clutch. The basked was in very good condition, with no need for any filing. So I just changed the plates. However, of the 6 springs on the back of the clutch, the 3 smaller are in bad condition. Loose in their housing. Which if I recall correctly could cause some knocking. If your not sure which ones I mean, I took a photo... http://www.kirby.ie/GS1100/Clutch-small.jpg

Unfortunately I can't put it back together because the gasket set I have included an incorrect gasket. Its slightly too small. So I have to go buy some gasket paper tomorrow (

Thanks to everyone who has offered advice so far. Its much appreciated!

- RK

[saaz]

I have had the same problem twice on mine. It leads to a noise more like a louder clutch rattle rather than a knocking, but depends how bad it is. I had the clutch strengthened with springs and rivets redone.