Judder on slowing down

[Oggers]

Gents

Bit of advice please. Triumph T120 judders slightly when coming off the throttle - especially at lower speeds. It is not severe, but perceptible nevertheless. Difficult to describe, but it is not a smooth transgression to standstill. When accelerating it seems fine though.

My thoughts

Clutch pressure plate needs adjusting. Perhaps not an even gap all the way round.
Clutch springs not equally tensioned
Carbs out of balance.

Anything else you feel I should check?

Any advice much appreciated as always   

[iansoady]

I can't see how your first two could cause this - provided you're not dec lutching of course. Flutter on the auto advance?

[R]

Check for chains that are too tight - especially the primary.
Also that all the engine/gearbox mounting studs are good and tight.

And that the chain line on the rear chain is correct.
And even that the rear shocks have some damping left in them,
and the front wheel is in line with the rear.
And the tank has all its rubber mounts in good condition.
A lot of things go into a sweet running bike. Think laterally ... ?

Also, does it idle smoothly and reliably ?

[Oggers]

R

I've subsequently been told that it could be primary chain too slack! As it happens, there is around 1/2 to 1" play which suggets it is OK. I'll measure more accurately though.Other things mentioned include clutch cush drive rubbers and rear wheel splines - if QD wheel.

[Rex]

How would a slack chain give "Juddering"?
Then again worn QD splines clonk when accelerating of decelerating...hardly a juddering sensation. Cush drive rubbers (worn out) nope, can't see it.

[john.k]

Primary chains often wear in two or three spots,and adjusting them needs extreme care that the chain isnt too tight in places .........best replaced if any wear at all.........always be sure the number of links is not a multiple of the engine sprocket teeth.

[iansoady]

Gearbox mainshafts are also often slightly bent.

[Oggers]

Update. Primary chaincase was low on oil. This has improved matters but not completly cured it. Tank rubbers fine, wheels in line, final drive chain seems OK. Other thoughts - slack/no grease in the swing arm bearings perhaps?

[R]

Crankcase/gearbox mounting bolts are ALL tight ?

Does this bike have a headsteady ?
If this is loose - or missing - could be a problem.

[Oggers]

Good point about crankcase/gearbox bolts and head steady - will check.