Ping centrepetal clutch fettlers.

So, Yamaha Majesty YP250 MOT'd today and after I took it for a little
shake-down run.

Something that I thought might go away after a run but didn't was
quite a bit of drag on the transmission, even at tick over (sufficient
to make paddling the bike backwards with the engine running quite
difficult and when on the stand you couldn't stop the wheel spinning
with yer boot (suggesting it was more that just 'drag')).

So, I stripped it out this evening and found 2 of the 3 clutch return
springs missing? What's that all about then? Could they have just
broken and come out of the housing somehow or has someone taken them
off to overcome another issue (or just bodged it generally)?

Cheers, T i m

 

Performance mod, innit?
Well-known and mysterious are the ways of the back-street teen tuner.

 

Ah, indeed, however I'm not sure a 250 Majesty would be seen as a
street-cred-ped. ;-)

The PO had the bike quite a while (a few years) but only generally
used it to get from Herts to Gatwick where he would leave it in the
car park (free) while he went to his place in Spain / wherever.

I think he mentioned he'd had the belt changed a few hundred miles
back but that could have also been a few years. Had it not been road
tested afterwards the fitter may not have realised the springs were
missing.

With hindsight the PO did explain his starting sequence involving
keeping the bike on the stand after starting for a bit and when it had
'warmed up' dropping it on the floor, after that it was ok in use [1].
Daughter rode it home from Clacton (and we hardly stopped) so
yesterday was the first time I'd had the thing on the road myself to
see what it was like.

T i m

[1] I thought it could just be how_it_was or because it was getting a
bit tired? Her Piaggio Skipper used to do similar when cold but was ok
when warmed up.

 

Well it certainly seems keen to get away, lift yer feet up on tickover
and it's off, even two up!

I bet.

There is no way they could have just broken and fallen out I guess?

Right, exhaust is stock (and as I said elsewhere I don't think this
has been owned by a tweeker). Rollers are ~ 20mm diameter (plus a few
small flats) and weigh 14g (but I can't find mention of what std ones
are in the manual). They look identical to a set I've seen on Wemoto.

It does give me that the 'Clutch – in revolution = 2,100 to 2,700
r/min and the stall revolution should be 3,700 to 4,700 r/min'. ;-)

Again, no mention of what 'std' is in the workshop manual. Again, it
looks untouched (but I appreciate that means little) ;-(

Phew.

For me the best combination would be 'working as Yamaha intended' ;-)

FWIW I have found mention of the free length of the clutch shoe spring
so at least I can see if the remaining one it stretched much / at all.
Theoretically I can measure the tension rate on that and then see if I
can find some from an old clutch or similar?

I'm going to take the lot over the bike shop now and see what they say
(and to take the clutch apart).

I notice they do the complete clutch / drum assy on eBay new for about
£100 delivered but from China? Are they likely to be as good as the
original kit (or could the original have come from the same factory in
98)?

Cheers, T i m

 

Get new clutch springs, check the clutch drum and that it isn't worn too
much or warped. Could just have broken off, it'll help the pull away no
end fixing it. As in, it'll pull away much quicker.

 

MAJESTY DX 250cc 20x12 14.0g
MAJESTY ABS 250cc 20x12 11.5g

SNIP!

No need to replace the drum unless it is damaged. Shoes and backplate
assembly is around £60 e.g
http://www.gileraspares.co.uk/spare...P=CLUTCH&Model=YAMAHA MAJESTY 250 - upto 2001

 

Cheers, that fits at least then.

I guess for damaged read scored when it comes to such things and it
was a bit. I say was as I've skimmed to high bits off on the lathe
tonight.

Cheers again.

Update. A mate found a new clutch back plate assembly for me (was
fitted briefly to an X Max but wasn't the problem) but from what I can
Google it's designed for a 125. Part No: 1B9-E6620-00. It's exactly
the same as what I took off except the springs look much bigger and
feel much stronger (it could just be that the one remaining spring on
my old unit is shagged). My data shows the original clutch as a
4HC-16620-00. I *think* may have seen mention a substitute part, could
the 1B9 item be it?

Anyway, on the grounds that I've little to lose except a bit of time
I've skimmed all the rollers down to a nominal 19.70 mm dia (min 19.5
according to the manual. They still have some small flats but
generally much better) and reassembled the variator and clutch ready
to fit when I next get a chance.

Before I do, can you confirm if the 'new' clutch assy is (or isn't)
suitable for my YP250 and if not what am I likely to find in use?

Assuming the clutch springs are now stiffer (and the clutch arms the
same weight as the originals) I guess they will take more revs before
they start to throw out so would cause the clutch to slip more
(longer) during takeoff (as it's trying to pull away on a slightly
higher gearing)? Or am I way out?

Cheers, T i m

 

;-)

Trouble is the frictionable material on the two clutch surfaces that
have been 'dragging' is nearly worn down to the metal so even if I got
new springs I'd be stuffed there?

As I've added elsewhere I'm trying a nearly new clutch a mate has
found for me and if that doesn't work (possible wrong spec) I have the
old clutch out to either repair (reline, new springs [1]) or replace
as / when I get the cash / time.

Cheers, T i m

[1] Partly for the crack.

 

If it fits then it should be fine. You are right about the higher revs
before the clutch bites but that shouldn't be a problem - the engine will be
delivering more torque at higher revs so the take-up should be smoother and
with better initial acceleration. However - if the springs in the clutch
assembly that you are considering fitting are non-standard (I think they are
the same standard spec on both 125 and 250) then there are possible
difficulties. If they are too stiff then you may have to scream the engine
before the clutch bites.

BTW - re. the missing springs. The other two may have broken, see
http://www.twistngo.com/userforum/viewtopic.php?f=6&t=5523&view=next

Possibly the previous owner couldn't be arsed to replace them and just put
it back together with one spring.

 

Yep, it seems to have done (well together rather than on the bike).

But might sound a bit 'busy' if just pottering in traffic? It will be
difficult for me to judge as I'm only used to it as it was, pulling
away at tickover revs.

Well the 125 - 250 things is reassuring as my mate *thought* the
clutch was from a 250 X Max but the only reference I could find to
that No. was re a 125. If they use the same components and in the same
role (and I have since found an X Max 125 parts list and it looks
similar at first glance (but gearing ratios could be different etc))
then it could be game on. ;-)

Understood, but I think it's only going to be any difference between a
YP250 and X Max 125 so ... ?

Hmm. I wonder if they did redesign it for later machines using the
same transmission (bigger springs)?

As mentioned elsewhere the PO only used it as a DIY airport Taxi and
generally put it into the shop for most work. I'm pretty sure he
wouldn't have gone as far as taking the tranny cover off!

I have no idea of the bikes history before that though.

Another question if I may. When I took the variator apart it was
fairly well lubed up with a very black sticky grease. There seems to
be two systems out there, those that are designed to run dry and those
that are designed to run lubed. After a quick Google I decided to
re-lube this one upon re-assembly and I used a general purpose high
melting point lithium based grease. I also use it on the spiral action
of the rear sheaves etc. Is this ok would you say?

Cheers, T i m

 

If the variator was working OK with greased rollers before you took it apart
then it should be fine after re-assembly. I hope you only used a thin smear
beause you really don't want any risk of grease on the pulleys or drive
belt.

 

Swot I though (but just wanted a 2nd opinion).

I used a bit more than a smear but not OTT as it seems this variator
is very much designed to run 'wet'. By that I mean there is a large
'O' ring around the outside of the ally body of the variator itself
and when you put the steel cover on it effectively seals the assembly
against any grease [1] from being thrown out by centripetal force.

It would be like using the spin drying function of a washing machine
after taking the door off.

I'm off out and about now but after I've synched up with Paul I hope
to put it back together later.

Cheers, T i m

[1] Ok if grease but oil would spill out if you laid the bike on it's
l/h/s etc.

 

Heh.. it's an 'on a budget' scooter. Rather like my one has turned into
[1]. Some spotty yoof nicked the end of my kick start outside uni. So a
mate welded part of a table leg onto the end of the kick starter. It's
not pretty, but it works. Hurst my foot less when starting the thing too.

[1] Apart from the last rebuild that included a rather mice long stroke
crank and new piston / mains / water pump / head.... doh.

 

I miss my old grease filled variator, you didn't need to replace the
rollers every couple of thousand miles. I may yet find an older greased
type variator off an old Runner 180 if there is such a thing any more,
or modify my existing Polini variator.

 

<aside>

What did he say?

 

It is indeed but one that seems to be performing much better now. ;-)

I'm not sure if the new clutch is 'right' (as in performing as / when
it should) but it's certainly not doing the draggy thing and the
'variomatic' part of the transmission also seems much more apparent.
ie, When you give it a bit of throttle at standstill the revs now come
up and you feel the clutch start to bite. Then the revs seem to stay
the same and the speedo just goes from 0 to about 60 with no real
obvious change in engine revs. The only bit I'm not sure about is if
the clutch is now coming in a bit too late, as if the clutch springs
were too strong? Mind you the only test I've done with it in it's
latest guise is two up and a farly heavy two at that. ;-(

It is a bit weird having no direct drive from 0 mph (as with a manual
bike, clutch / gears etc) and you have to learn a slightly different
technique for slow speed manoeuvring etc but it does seem an ok scoot.

I let the Mrs have a go on it along a wide empty road and she got on
with it straight away (but then she's used to 'different' handling via
her XV750). She even did a section of the journey home with all 16.25
st of me on the back. It can be leaned further than her XV750 and even
two up we haven't grounded anything yet.

It isn't the same ride as a big wheeled bike and like many 'commuting'
type machines seems to suffer the 'rubber hinge' issue. I've changed
the fork oil, checked the head and front wheel bearings and it's got
new tyres front and back but the front definitely feels a tiny bit
'drifty' when bundling along in a straight line.

As something different though I'm quite impressed. I like the electric
start, a fuel gauge, all the storage, seat comfort [1] and the fact
that it's a liquid cooled 4/. I should imagine the weather protection
would be good in the winter. The variomatic bit means it's quite easy
to frustrate those drivers who thought they would easily get by then
cut up 'a scooter' (even with my bulk at the helm).

Why? I mean, are they sought-after or collectable etc?

Result then. ;-)

Ah, that's the hook isn't it ... I was looking to replace the variator
rollers (anyway) and someone sent me a link to Dr-Pulley:

http://www.unionmaterial.com/rollerweight.htm

And then it can be a slippery slope towards Malossi, Costa and other
tuning kit. However, now it seems to be going ok and I've sorted some
cheap replacement mirrors (with a little lathe work) it's going next
to the CB Two Fifty [2] ready for when the mood / need arises.

T i m

[1] All be it slightly cramped for me at 6' 2" ... but that's the way
it is on most bikes.

[2] That really needs one fork leg re-chroming. ;-(

 

Oh, as often as that eh? A mechanic mate did mention many clutches
now seem to be run dry but rather than experiment with this I re-lubed
it and it seems fine. What are the chances of these rollers being the
original ones at 24k miles?

Even with the levels of wear I noticed on the transmission on this
scoot (pulley sheaves with distinct groves near the outside, flatted
rollers, scored clutch drum, min spec belt etc etc) it all looked
sufficiently re-useable, at least till I've worked out if it's a
keeper or not.

I should imagine to replace the lot with new Yam stuff would be quite
expensive (the RRP on just the clutch was £130) but then I guess it is
like replacing most of an equivalent conventional gearbox. ;-(

T i m

 

On a soft tuned engine like yours, I'd say it would be unlikely. They're
a service item. My rollers run dry, and the engine is quiet aggressive
for a scooter, plus I do a lot of town running about which means the
rollers are up and down their ramps a lot.

All scooter clutches run dry, the number of shoes just seems to vary.

Try using after market parts, clutches do seem to be a lot cheaper.
Variators vary, with the original part being cheaper on my one. There is
a shop online that do lots of bits and bobs for 4 and 2 stroke, small
and large scooters.

http://www.scooter-center.com/1024-e.htm

 

The revs sound right, the variator is doing its bit well. Dragging is
bad in the clutch department, and will overheat things / wear them out.
Mind you, too much wear on the clutch shoes and drum will alter its action.

My clutch only fully engages after about 20 mph, until then it's
slipping all the time. Keeping the engine pulling against the back brake
helps low speed manoeuvring.

Scooters tend to mount the engine / swing arm unit on rubber bushes,
which makes for wibbly handling. I've got solid bushes in mine, and a
modified engine mount to stiffen things up. Rear tyre pressure makes a
lot of difference on my one, as does having any play in the steering
head bearings.

Variomatic is _the_ thing to have for small capacity machines. Ok, it's
not as efficient as a conventional gear box, but it more than makes up
for that by keeping the engine at the right speed almost all of the time.

I think it was just some wanker trying to be funny.

Interesting, but they've cheated in the pictures. The plate isn't in the
same position in the two pictures.

I'm already there with Malossi, Polini, mazzucchelli, Stage 6, PM and
some Shiny Red custom made bits.

 

Belt and rollers together typically then?

http://shop.wemoto.com/pictures.dyn?u=2147797qqq5828248
http://shop.wemoto.com/pictures.dyn?u=2147797qqq5828174
http://shop.wemoto.com/pictures.dyn?u=2147797qqq5828502

On that last one, do some variators come with a big spring like that
as I've only got such a thing on the clutch?

Understood. Have you tried the Dr.Pulley non-rollers?
http://www.unionmaterial.com/rollerweight6.htm

Doh, I meant to say 'variator'! The only other bike I've got with a
dry clutch is the R100RT. (and it's very dry atm as it's in a box
under the stairs). ;-(

Ok ta.

I did see the entire clutch (sheaves, hub, shoes, drum) on eBay for
£100 delivered but I've no idea about the quality?
http://preview.tinyurl.com/m3borr

It looks identical to mine. Is a LINHAI 250 yet another machine that
uses that engine unit. How many others are there!

Bookmarked, thanks.

Oh, assuming most scooter final drives are like the unit on this
YP250, is there a good technical reason why they would spec an SAE
10W40 oil in there and not the (more typical?) 80W90 'hypoid / gear
oil'? Ok, I can imagine there would be a touch more drag with the
heaver weight oil but would it be sufficient to want to use a lighter
oil so potentially offer less protection?

T i m