1200 laverda....noise-sorrows....noisy 5th gear

R

rully

New member
Location
germany
hello,

still" fighting" with the "lady"...
it`s a 180 degree 1200, nd-version. history unknown.

last fall, doing the first ride with this engine I was scared by some unusual noise from the LHS...primary drive region.
after replacing the primary chain(s), the clutch rubbers, doing an exact alignment of the clutch basket with the primary sprocket, having tried all the different manners of tensioning the primary chain....the noise was still there.
then I found some grinded metal near the LH-crankshaft bearing.....sent the engine-block to keith nairn in glasgow(all "others" told me to ask them again next year....), who found a worn LH-crankshaft bearing and a crankshaft out of balance.
gearbox was also checked/repaired by him(several items replaced).....overall good, high quality labour.

after installing/completing the engine(barrel, pistons, head and clutch weren`t sent to keith....).....the noise is still there:
  --  overall in the 5th gear
  --  sound character: swooshing/grinding(like a rough bearing...). no knocking, no "hard" mechanical noise
  --  can be heard with the engine pulling/throttle open, but even more when the engine is "pushed"(throttle closed)
  --  stops immediatly/at once 100% when pulling the clutch lever.

lately I had a "compare-ride" with another laverda 1200:
beside from the usual, decent  "sound" from the primary drive no "extra sound" in 5th gear....

anybody any idea?


thanks and regards


christopher
 
But he didn't have the full engine to be fair, suggesting the issue lies in the parts not sent, like clutch for example.
May not be, but worth investigating closely.

I see you live in Germany, surely you have someone experienced in Laverdas nearer you?
Like OCT, Cycle Doctor or Laverda Paradies?
 
...in NO way I wanted to put a shade of doubt on keith`s labour!!
good, high quality work at a fair price. tanks for that, keith.

and therefore I suppose that the problem is not inside the engineblock.

as the noise stops at once when the clutch lever is actuated.....the suspicion falls on the clutch, of course.
maybe the/one of the needlebearings....
but why (nearly) only in 5th gear?
 
rully said:
...in NO way I wanted to put a shade of doubt on keith`s labour!!
good, high quality work at a fair price. tanks for that, keith.

and therefore I suppose that the problem is not inside the engineblock.

as the noise stops at once when the clutch lever is actuated.....the suspicion falls on the clutch, of course.
maybe the/one of the needlebearings....
but why (nearly) only in 5th gear?
Click to expand...
Most load on gearbox/clutch is in top makes perfect sense to me.
Noises can be very subjective, can you run her up on the stand in fifth and post a video sound file ?
 
Brett said:
Most load on gearbox/clutch is in top makes perfect sense to me.
Noises can be very subjective, can you run her up on the stand in fifth and post a video sound file ?
Click to expand...

Hmm.  You reckon it's load related, but there's no load on the drive train when running it on the stand. Perhaps he should load it up by putting the back brake on. Being able to diagnose it from a sound file is a bit of a long shot though.

If it only does it in 5th gear, it might be related to how the gearbox works. 5th is the only gear (other than neutral) that unloads the countershaft. All drive is through the main shaft and the countershaft is just idling.

I can't remember the sequence of gear/dog movements for the various gears, but it's probably worth looking for something that's noisy when the countershaft is unloaded. Perhaps a bush or bearing that Keith didn't replace. Or maybe a slightly bent shift fork that's allowing a set of dogs to rumble against it's adjacent gear.

Pulling the clutch unloads the gearbox, so any load-related noises will disappear.

Christopher, one of the words you used to describe the noise was "swooshing", which implies that it has a frequency between swooshes. If you can estimate how many swooshes per second at a particular speed, that would help work out where the source of the problem is. Calculating the speed of rotation of various components in the gearbox and matching them to the noise frequency can often pin-point a noise. I've done that on several occasions with gearbox problems - identified a noisy bearing just by the frequency of the noise. You might need to ride slower than normal in 5th gear to be able to count the noise pulses.
 
I bought a stethoscope with an extended probe .......... you can find a bodgy bearing in a matter of seconds. Although, you'd need to be wearing a jockey's helmet and use your left hand to control the throttle while riding in top gear, what could possibly go wrong  :o

Frequency between swooshes ......... sounds like a buggered final drive chain.
Yes, I know, only in top gear, but hey, that's what the sound reminds me of. 
 
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