Transmission backlash

[Petemate]

Bike - LA250 Custom, engine unit same as CB250 Nighthawk, CMX250 Rebel, and CD250U.
Got the bike in Nov 2013, delivered, never rode it until I put it back on the road after a full strip and rebuild.
Advised on sale about 3rd gear noise - sure enough, 2 and a half teeth stripped on one of the gears, fitted new both 3rd gears. As far as I could see, there were no issues with all the other gears and bearings, or splines etc on the shafts.
Once back on the road, I noticed a slight whine in 4th, which has progressed to now sound like a Blackpool tram, and fifth is now whining a bit. 3rd of course is OK....
Now to the current problem. From the moment I took the first tentative rides after putting it back on the road, I noticed a 'clack'/'clunk' on take up letting the clutch out. It will occur once I have closed the throttle (at which there is another clunk as the drive reverses) then recur when I open up again. This has not got any worse in the few thousand miles I have put on the bike. It can be reproduced in 1st, 2nd, and 3rd but to be kind to the clutch I have not tried it in 4th or 5th.
To my mind this rules out any issues with dogs on the gears and points to possible problems with splines etc. I did consider the rear sprocket cush drives (mine are the 'silentbloc' type) but checked them today while attending to a rear brake squeal and all is OK there.
When I was rebuilding the engine I paid particular attention to the clutch basket slots and internal splines in the centre and the splines on the input shaft, also the output shaft on which the front sprocket sits. Nothing was amiss there, and still isn't, (checked today) and the clutch plates are new (fitted a year ago)
I am not going to purchase a new pair of 4th gears, and am going instead to get hold of a complete gear cluster from a low mileage bike - there are going for less than the pair of 4th gears including delivery.
Assuming the bike doesn't blow up in the meantime, I intend to take it off the road at the beginning of December and remove the motor and strip it down and get out my magnifying glass!
Footnote - I know I tightened up the clutch centre nut (and everything else) to the correct torque loading on the rebuild. I am baffled at the moment but hopeful that I will find something obvious when I strip it. The clutch is wonderfully smooth both upchanging and downshifting. Once I have fed the clutch in, traffic lights grands prix are great.
Pete
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82 not out....1983 Honda LA250 Custom
2008 Saab 9-3 1.9 Tid 150 Vector Sport estate
2005 Stirling Eccles Topaz 2-berth

[bikenut]

mmmmmm a smashed gear.......or pair of gears.....

I assume the pegs in the rear spocket are tight, and a good fit in the silent block rubbers.......which you say are ok. no sign of breaking up or parting company with the steel inner and outer and hub, circlip arrangement to keep the sprocket in place??

Swing arm and engine bolts all tight ??

How is the handleing, at the rear?? Bike seems to have a bit of a mind all of its own ?

That basically leaves the engine and transmission.

The clutch hub nut and "outside " washer, the clutch nut fitted flat side out ? what torque did you do it to ?

I assume the crank gear bolt is tight ?

How is the clutch drum cush drive ?

Any judder in handle bars when braking ?

Rear chain tension all ok ?

Post a picture of the rear sprocket to wheel arrangement. :karma:
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nuts about bikes

[Petemate]

Thanks bikenut for the quick response.

Sprocket pins all tight and correctly positioned. A good fit in the bushes, which have no signs of the inners parting company with the rubbers. I inserted a pin in each of them (pins removed for inspection) and moved them sideways to check the rubbers. The circlip is a good fit and there is no play in the sprocket when it is refitted.

Swinging arm smooth and engine bolts all tight; handling perfect - I can hammer the bike round bumpy bends and no snaking etc.

Can't remember the torque setting for the clutch nut but I know I tightened everything exactly according to the book; washer correct way round etc.

Crank gear tight.

Ckutch drum cush drive? If the 233cc lump has one in its clutch I didn't know - if it has, then that will be my first line of investigation when I strip it.

No judder at the 'bars when braking.

Rear sprocket to wheel arrangement: (pic of CD250 used as one of my type not available)
https://i460.photobucket.com/albums/qq324/Petemate_01/Miscellaneous/Current%20wheels/rear%20wheel.gif

Although the 4th gears are now noisier, I can discount them as the symptom has been in place from the word go with no worsening and as stated, can be reproduced in at least the first three gears. A good point re cush drive and I am hoping that there is some sort of one in that outer.
Thanks!

PS note to Teflon-Mike: Mike, is there any sort of cush drive in the clutch outers of these little 233cc lumps? TIA!
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82 not out....1983 Honda LA250 Custom
2008 Saab 9-3 1.9 Tid 150 Vector Sport estate
2005 Stirling Eccles Topaz 2-berth

[bikenut]

post an exploded view of the clutch please.

Most clutch baskets have a cush drive, a spigot fit of the clutch gear to the basket, all held in place with a riveted plate.

These parts wear, rock hard cush rubbers and slack, wear on drive gear/basket spigot, meaning play and back lash ( you should see my kwak one, cush and 3 drive pins, cush "gone" so drive via drive pins, mega back lash, new parts are 100's £ ! been trying to get an overhaul kit, new rubbers and rivets etc. but no luck so far, may have to either use bolts or make new rivets so I can disassemble, sort it out, and re assemble, eventually. ) misalignment/mesh with drive basket and crank gears, loose rivets and "steel plate that holds the lot together" ) meaning noise/back lash/ jerky transmission, just like a landy with buggered half shaft splines and Drive plates, not to mention completely buggered UJ'S etc. Press throttle, count to 2, hear "bang" then accelerate, quite comical really but dangerous.

You fitted the clutch nut with flat face out ?
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nuts about bikes

[Petemate]

[bikenut]

Yep, I liked the boss, but he was a twat to work for.

Boss, the landy needs xyz, half shafts and drive plates.

Weld it he says, but boss you cant really do that, just weld it he says, but boss, WELD IT ! he ordered, so I did.

Was told "what have you done to the landy, is brilliant now", lasted about 4 weeks and so did I, I left.

Difficult bloke to work for.

Anyways could you post a picture of the engine, both sides please.

5 gears and nutted on clutch hub, ala superdream ( bloody nightmare more like ).

Carb ( twin carbs on yours or single ? ) imbalance can cause a thud thud thud noise ( as can so many other faults like balance shaft problems and bottom end ) which may lessen when clutch pulled in, and slightly more so when in gear holding the clutch.
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nuts about bikes

[Petemate]

[bikenut]

If you look between the steel plate and the basket you may see the rubbers, or the "rombiod" if that's the right word, the shape the cush blocks sit in between gear and basket, its the rivets that are the problem.

Older triumphs have a cush in the clutch that runs close to oil, but i think they are "round rods"? will check.

Large pieces of oil tolerant "rubber" or the stuff engine oil seals and cam chain slippers are made from may do, trimmed, but where from ? or from what ?

The kwak i have has a largish block in the cam cover, to form an arc for the cam chain, a cam chain slipper. E15 each may be big enough to do 2 cush segments ?

I heard of someone in holland ? that used bolts/nuts to replace the rivets.

Been trying for ages to get an overhaul kit for the kawasaki, Z1 kits you would think are available, but from where, that's a real classic isn't it.

I don't have one of them, Z1 I mean.
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nuts about bikes

[bikenut]

the black plastic mats that farmers use, or on factory floors, engineering w/shops , that stuff maybe, quite tuff, but is it oil tolerant ( engineering w/shop floor so should be skilly proof ), and hot oil at that, anyone got a small bit to check for us please, pretty please?

or know of a large cheap cam chain slipper m/cycle or car or similar ?
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nuts about bikes

[Petemate]

Thanks bikenut - some good points and good ideas there.
Regarding spotting what is in there, looking at the pics of the baskets in the eBay ads, side views don't seem to give any idea of innards. I reckon I'll just take mine to bits when I get it out and if I foul it up I can just get a replacement - they are going for reasonable cost.
Pete
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82 not out....1983 Honda LA250 Custom
2008 Saab 9-3 1.9 Tid 150 Vector Sport estate
2005 Stirling Eccles Topaz 2-berth

[Petemate]

Took the clutch out today. I was expecting to find massive play between the sprocket and the basket, with a load of rubber particles/debris lying at the bottom of the crankcase. Nothing. No play whatever between the sprocket and basket. Gripped the sprocket by wrapping a piece of webbing round it and holding it in the vice, then a piece of wood across the slots and no movement.

Now to the nitty gritty. The bike is on the sidestand. When I grasp the end of the mainshaft with first gear engaged, I get quite a bit of rotational play, with the exact 'clack' which I experience when pulling away. Far less rotational play exists in all the other 4 gears, with exactly the same clack. Looking at the manual pics of the gears the movement within the engagement of the dogs seems to equate to this play - am I worrying about nothing more than a characteristic of this tyoe of gearbox? (ie constant mesh dog engagement) Strangely however I don't remember hearing these clacks on all the other bikes I have owned, Jaoanese or otherwise. Can someone advise if they too hear this clacking every time they pull away?

Everything (without stripping further, and as far as I can see) was as it should have been, eg the clutch assembly was tight, its washers the right way round, the crank and clutch basket gears are perfect, the front sprocket is secure and no play in the splines, etc etc.

I am going to do a filter clean while the cover is off, and pop some clean oil in there after reassembling it all. Lucky I don't need a gasket; when I put the engine together I used Wellseal thin jointing compound sparingly on the crankcase and grease also sparingly on the cover and the cover came away easily by merely operating the clutch lever. The whole engine has been oil tight so much so reminding me of how my old Triumphs were not lol.
Later this year as a winter project I will be completely stripping the motor to sort the gears out (the 4th whine mainly). I plan to get hold of a low(ish) mileage gear cluster, there are several out there and happily for me the internals of this motor are identical with many others in the 233cc range.
Pic later showing the play in each gear which I am now convinced is normal dog to dog and dog to gear holes.



Pics best I could. The dial type rig I made shows the slack in each gear. Having studied the gear train and how each ratio is not as straightforward as previously thought, it appears that (especially in 1st) the slack rotations are linked to the movement between the dogs, and there are occasions where more than one pair of gears are transmitting power via dogs and holes. As far as I remember the dogs and all holes in the gears were in fine condition, and considering that the 3rd gears are only just over 2k miles old, this leads me to believe that all this slack is merely characteristic. (I hope lolol) The diagram of the gears is great fun to work out....
Time will tell.
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82 not out....1983 Honda LA250 Custom
2008 Saab 9-3 1.9 Tid 150 Vector Sport estate
2005 Stirling Eccles Topaz 2-berth

[Petemate]

I've had a further thought on this problem. I said that I can find no play between the sprocket and basket on the clutch outer. However, while lack of radial play is desirable, surely one should be able to reproduce cushioning movement? And if not, then the assembly might as well be a solid bolted one. So I am considering the possibility that after 33 years the rubbers in there my have deteriorated in that they have become hard, and therefore are no longer able to 'cushion'. This would surely explain the gear dog clacking which should be masked by the nice soft cushioning of the rubbers if they are serviceable.

Has anyone had experience of checking a clutch basket for the softness of the cushioning? - Teflon-Mike - whadja think?
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82 not out....1983 Honda LA250 Custom
2008 Saab 9-3 1.9 Tid 150 Vector Sport estate
2005 Stirling Eccles Topaz 2-berth

[bikenut]

A belt drive option?? could you post cmsnl view of rear wheel belt drive sprocket please ?

Could you also post a cmsnl view of the clutch cover and crank, as, can I see a clutch cover oil way ala cb125s cb125t etc......

Has a tube gasket blocked an oil way and is there a centrifugal oil filter on the clutch side of the crank??

A riveted clutch basket suggests a cush drive, post a picture of the back of the clutch basket, inside of clutch cover and end of crank.

Modern gearboxes often have power flow involving many gears........large backlash due to sets of gears and dogs/holes etc......but a clack on take off....suggests something is moving/sliding/slipping then driving, on a shaft?

pictures first...
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nuts about bikes

[Petemate]

[bikenut]

So there is a sprung loaded "piston" affair with a hole in it that lives in the clutch cover and lines up with the hole in the crank, an oil feed to the big ends......or it may live in the end of the crank and line up with an oil hole in the clutch cover.....an oil feed to the big ends.....

Will take a picture of a clutch basket a have stored in the shed, a picture of the back of the basket, hopefully showing cush rubbers or where they live.....

Could you give a link to the cmsnl pages for the belt drive, need to check f and r belt sprocket sizes etc as well as belt length, may fit a bike/bikes i/we have to rid ourselves of chains !Thanks

Had a negative feedback on cush rubbers from Wiseco uk, but still looking for rubbers for the kawasaki cush drive ( and pin ) clutch
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nuts about bikes

[Snod Blatter]

I can help with the oil piston thing, it is spring loaded and lives in the end of the crank where it is pressed against a face on the clutch cover.

For what it's worth my CB250 has 82K on the clock and doesn't have this clack, or at least I've never noticed it. The only lash it has is that the rear sprocket no longer snugly fits the rear wheel and flaps about far too much, a new washer and circlip helped (the old ones worn surprisingly thin!) but it obviously flaps about, with the studs almost grazing the inside of the swinging arm. I'll have to replace the wheel if it gets any worse, or perhaps find another washer to pack it out with..

Sorry to be somewhat simplistic about it but are you tightening the chain enough?
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1994 CB250, 1984 CBX250RS-E, 1989 K100RS, 1995 TRX850, 2016 Z250SL

[Petemate]

[Petemate]

[bikenut]

basket well didn't work will try again later
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nuts about bikes

[bikenut]

superfast broad band my arse!
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nuts about bikes