400 four knocking noise.

[Clem2112]

O rings may create more friction or possibly wear too soon unless greased  ? .

There was a website describing a full carb strip and rebuild including making those felt rings.... the link was on the now defunct CB400F.btinternet site but might exist on Yahoo groups?

[Lynx]

O rings may create more friction or possibly wear too soon unless greased  ? .

There was a website describing a full carb strip and rebuild including making those felt rings.... the link was on the now defunct CB400F.btinternet site but might exist on Yahoo groups?

Yes I got the instructions off Yahoo Groups.

[Lobo]

Thanks OddJob, good info.

With the bike on its centre stand, and at low idle, if I were to 'load' the engine... ie put it into gear & apply gentle brake to the rear wheel, should the knocking noise disappear IF it were due to primary chain rattle? (presumably carb imbalance would 'fail' tis particular test)

Lobo.

[Clem2112]

Then there is that set of damper/cush rubbers inside the clutch basket but they are not serviceable (and not available) as the basket is riveted to its gear of course.
These segments of rubber will be as pliable as hard plastic now and zero damping - another source of noise and chatter further along the drivetrain.
New clutch basket if there is too much play but opinions vary. If the rivets are tight I think it's OK.
Heard somewhere on the web that a few Kawasaki enthusiasts have had sets moulded for their Z650s clutch baskets.

If I could find a place to rivet the gear to the basket it  would only need a way of making the dampers !
 


 

[ttr400]

Yes the play on the basket gear is due to the damper rubbers being hard and brittle. there will be no play in the rivet.
I do a few damper rubber sets made and have fitted a few. the assembly goes back together using HT M5 screws. the rivet hole is the correct size to just tap to M5.
Kevin

[Clem2112]

Kevin

Can I buy a set please - cannot see them on your website.
What would it cost for these with shipping to the uK?

Cheers

Simon

[ttr400]

Simon,

Replied to your email. but yes i have a few sets available for sale.

Kevin

[tom400f]

So....... popped round to Lobo (Simon)'s place on my 400F today to compare engine noises. Arrived at may be 1:45 or so and by that time Simon had already removed the clutch basket, replaced the cover, filled it with oil, started it (quiet as a baby) then put everything back again, refilled with oil ... all in a day's work.

Took my son with me. 120 miles round trip max attempted speed 85mph on the M3. Pulls top gear into the wind on pretty much all inclines bar one..... but I digress

We agreed that Simon's clutch sounds like a bag'o'nails at tick-over. Even in gear with the clutch disengaged and the rear brake on there is noise, whereas mine is quiet like that and just a bit of noise in neutral. Lines of enquiry such as (may be) dodgy pattern clutch plates to follow up. But yes, quite noisy if nothing to worry about.

Everything else about our engines sounds the same - silky rustling 

It has to be parakeet yellow dahling!!

[Lobo]

Yup, generously Tom came over, and there is a 'problem' with my clutch. Until yesterday I'd had nagging doubts as to primary chain, due a muted clattering in the sump area. I pulled out the dipstick - and bingo, the noise ramped up to a dry metallic clatter suggesting not primary chain as that'd be mostly immersed (=muted). And just to verify, I pulled out the clutch basket, rebuilt the casing... engine sillky / turbine like... no rattles from anywhere.
(Just for reference OddJob, rotational play in the primary shaft about 2mm at its gear circumference)
Help / comments then. Back along I wrongly stated I'd got a new clutch basket, actually its simply new (DSS) A & B plates & new springs. No discernible play in the basket when I had it out this am, all solid - using my toned (not) muscles anyways.
Very wary of ebaying a second hand basket as it could be no better than mine.
If its reckoned all due basket cushs - what is actually the SOURCE of the clatter, mine has zero play anywhere that I can ascertain.
Kevin - do you reckon your basket cushs will fix it.... can you contact pm me details if you think you can help? (Inc postage costs)
Cheers,
Simon.

[Clem2112]

Might be that the assembly is imbalanced somehow... Tolerances, etcetc.
That may give rise to another vibration and so more clatter.
 
Maybe re assemble the plates by turning them all 180 degrees in the basket?

[K2-K6]

I'll have a go at describing the sequencing there with what you've got.

The drive from the crank passes to the clutch, this is essentially another flywheel albeit remote from the crank. A flywheel wants to spin at a consistent rate (the main reason for putting one on a crank) and imparts it's inertia backwards down the primary drive route if there is a change in crank speed.
Bare with me while I try not to confuse myself here!
When the engine is running then for one crank revolution you will get first one cyl firing while it's paired piston is at tdc at no compression, and the other two pistons at the bottom of the stroke....this is then reversed for the other two cyl.....now these small four cylinder engines sound very smooth but at low rpm there is significant crank speed fluctuation when ever one pot fires as it first comes up to compression (only one cylinder doing this at a time remember) the crank slows, followed by acceleration as the ignition fires that cyl.
That speed change comes through the primary drive BUT is opposed by the clutch which is happily spinning consistently as it has no balance issues.

If you think of what happens to the primary chain top run as the crank slows but the clutch keeps spinning it should go slack momentarily....followed by a whack as the crank speeds up faster than the clutch inertia.......it's this, I believe, that the clutch cush drive is supposed to mitigate, i.e. when the chain twangs it's the cush that should allow some give to stop that being a mechanical clunk that you can hear from outside.

So if the cush drive has gone hard and it should have some elasticity when new, then the small shock load it should be absorbing is just not happening.

You can even get a good demonstration of exactly this process if you put most bikes on the centre stand and let the engine idle.....put it in third or fourth gear and watch the final drive chain as it clatters up and down (the rear wheel being a sort of flywheel will replicate the primary drive inertial effects only on a larger scale).

So in principle I'm saying that there is not enough controlled movent in the clutch cush drive and it's most likely that most older examples would be similar.

See what others reckon.

Nigel.

[Lobo]

Hi Nigel / OddJob,

First up that thrust washer thought is giving me a sleepless night; I didn't take one off, or put one back. Bollocks! In truth I'm thinking it simply remained in place on its shaft whilst I verified the no-basket rattle fix - mainly because I DO remember, on reinstalling the castellated nut only a thread or two (at most) exposed post tightening. Working in a bit of a rush etc!

Nigel... thanks for the explanation - which all makes sense....apart from the 'bag of nails' cacophony - ie a mixture of metallic sounds. Is it simply the components of the basket make-up, all the rings etc rattling individually - there are for sure an 'awful lot' of parts.  This all said, I would have thought an engaged clutch (ie lever in normal position) would be tight enough not to allow individual components to rattle.
Have taken a punt on a 2nd hand basket, and by way of a project plan to order a shiny set of those red cushes above.
Cheers for your thoughts / help,
Simon

[Clem2112]

I follow that...

The generator rotor also adds mass to the crankshaft mass to help reduce the speed fluctuations but there still isn't much flywheel effect overall.

The noise may also be worse if the cylinders are not all producing the same shove at idle?

When I had my original bike the knocking noise was less evident when the carbs were balanced and the timing was spot on.
Some bikes are also a lot quieter with the clutch disengaged. This de-couples the gearbox which mean less mass to be sped up and slowed down with each rev of the crank to reduce the noise.

[ttr400]

Hi Lobo, sent you a PM. seemed to hang up when sending so not sure if it went through?

Kevin

[ttr400]

Hi Simon, thanks.  sent you a PM.

Damper rubber kit, posting today via registered airmail.

Kevin