Downshifts getting herder when engine warms up

[PieEater]

Hi Fokkers - bike has done just over 60,000 miles and downshifts are starting to get harder to engage. I've adjusted the clutch cable from the top adjuster so there is some but very little slack, I've also adjusted the lever span outwards so the cable is being pulled in a bit more. Is it time to replace the clutch or is there something else I should be looking at first?

[agricola]

Always best to start with the cheapest option first if youre not certain its the clutch plates etc. Try a new cable.

[Trebus]

Might be worth greasing up the rose joints on the shift mechanism. There were some problems reported with the blanking plug falling out at then end of the main shaft causing oil starvation issues. 

Possibly some wear in the basket fingers which much need dressing.

That’s where I’d start after ruling out the cable.

[Gnasher]

Check both ends of the cable for Adjustment/cable operation/wear or damage, if all is well you'll need to go deeper. 

First check the clutch push/pull rod bearings, the top one can be done without removing the clutch cover.  If there's any play it's buggered and will need replacing, fairly common on bikes 30k plus.  The seal starts to degrad and water/crud get in, likelyhood is the bottom is ok as it's inside the casing but check it.  The mechanism only moves a few mm at the bottom, if the top bearing is shot it will not release the plates properly. Giving you hard gear changes.

If that's all ok than check the ends of the push/rod for wear and then it's the plates, basket.  Chances are it's at worst the top bearing.

If all of the above is good then you're looking at worn possibly damaged selector mechanism or dogs.

[PieEater]

Thanks guys, appreciate the advice, this will be my winter project !!

[Gaz66]

Thanks guys, appreciate the advice, this will be my winter project !!

Howdy Pie.

I added stainless springs on the clutch end of the cable on mine, sourced thru eBay, pulls all the slack out the cable, even with a slinky glide aftermarket cable, also fitted a new OEM spring on clutch arm, my top bearing was well worn so replaced that too, it'd started grooving the shaft, couldn't find a decent 2nd hand shaft at the time, shaft only rotates 1/4 turn so old shaft went back in, top bearing is piss easy to change, i used a bolt, suitable sockets & washers & wind the old bearing out, fitting is just a reversal, cover needs to come off obviously, circlip on shaft under bottom bearing, bottom bearing will probly be mint as it's swimming in oil, top bearing's only splash fed so they crap out in no time, but it's an easy job, if you want bearing & seal dimensions, i've got my old ones saved.
Don't forget Yamaha don't make bearings, they're buy em in, they're fairly cheap from any bearing suppliers.
Obviously check clutch over while cover's off, might just need basket dressing with a file?

[b1k3rdude]

I added stainless springs on the clutch end of the cable on mine, 

There is already a spring on the clutch shaft arm (you can see it in the photo) that performs this function?, so your mod may potentially be masking that there is an issue with your cable? and making the lever harder to pull.

[PieEater]

I'm also thinking that because it only happens when the engine warms up (15+ miles) there must be a part that is expanding with the heat whilst another part isn't expanding as much in order to not fully engage the clutch, so not sure what that would be !?! Looking at Google a motorcycle clutch generally lasts 50k at most and my bikes done 64k so I'm thinking of getting a clutch kit and filing down any grooves in the basket before refitting as well as replacing the top actuator bearing. Does that sound like a plan?

[Gaz66]

I'm also thinking that because it only happens when the engine warms up (15+ miles) there must be a part that is expanding with the heat whilst another part isn't expanding as much in order to not fully engage the clutch, so not sure what that would be !?! Looking at Google a motorcycle clutch generally lasts 50k at most and my bikes done 64k so I'm thinking of getting a clutch kit and filing down any grooves in the basket before refitting as well as replacing the top actuator bearing. Does that sound like a plan?

Personally, I'd be pulling the clutch apart for inspection, might be summat obviously amiss, could be shaft bung that's come adrift & jamming clutch operation, never seen it myself, but it is a thing apparently, rough it up with emery cloth, degrease & high strength loctite it back in shaft end, if you're lucky it may be as simple a fix as that, if nowts obvious, you'll need to dig a bit further.

Have you considered a broken shift shaft return spring inside gear selector casing (left side of motor) only costs a gasket to check, seen load of these snapped on various bikes, got a new one on the shelf for mine (future proof it) etc.

Some things to consider:

Check clutch pressure plate & centre bearing.
Check clutch arm upper bearing wear, bearing & seal is an easy fix, shafts get mullered from worn bearings, don't think shaft are still available (Fowlers parts screen), won't be cheap either.

Pull all clutch plates out & measure total stack height.

I do this if total stack height is within spec:
Normal to see high spots/ bit of bluing on steels, check em on a hard flat surface, I use a thick piece of worktop, confirmed to be flat with engineers straight edge.
I block em flat with 400 wet & dry both sides, it deglazes steels & flattens any high spots, super clean everything, best reading specs on & scrutinise all friction plates (both sides), lightly twist em in fingers, check for cracking & excess wear on plate edge drive tangs, if all's good I think it's a waste of money replacing em, give friction a light deglaze with 400 paper on a block, brake clean em all &  throw in a new set of springs, EBC & Barnett do slightly heavier coils than OEM weight, defo a good move while its apart.

Outer basket:
It'll likely have some visible wear to alloy drive tangs from friction plates, if its not excessive, it's usually worth dressing back flat with a file/emery/400 grit.
Don't risk this process in situ, remove basket & get it in a vice, any swarf in a motor is bad Joojoo.

Basket centre needle bearing:
I check this by the rockin test, like you'd check a wheel bearing, rarely see knackered bearings.

Clutch centre hub:
These can suffer the same fate as the basket & have deep wear grooves from steels on drive side, same deal as above, decide if its shagged or worth time filing back flat.
Also a good time to consider improving oil flow while its apart, easy mod, while in a vice, drill multiple equally spaced 3mm holes in its grooves, slightly counter sink all holes both sides if access allows with a larger bit, all slipper clutches are drilled this way, pics on tinterweb if interested, (no brainer mod really).

Checking steel plates:
They're a stamped out part, hence the smooth edge on one side, no manual states the best orientation, I always put sharp edge facing the engine, benefits clutch operation.
Block sand em both sides with 400 grit, check on known flat surface for warpage, manual states 0.1mm feeler gauge test, rarely see any that need junking.

Checking friction plates:
I give em the "twist test" lightly twist em, check for cracking & obvious damage to friction blocks, if stack height of all plates is within spec & all plates are flat, I see no benefit in replacing an OEM clutch, plates are available in various thicknesses, stack height is important or you'll get slippage.
Most aren't aware & just chuck in aftermarket friction plates then wonder WTF is wrong when clutch operation is shit, you could get lucky & stack height may be in spec with aftermarket plates.

Obviously your issue could be terminal & buried deep with the transmission, hope the above helps in some way.

Lets us know what you find when you crack the motor open.?