Flywheel / rotor clearance?
 

As a brief foreword, after replacing cam chain on xt600e, engine started ticking/clicking while running, audible mostly from the left side.

Here's the full story of the search of the reasons.
http://www.horizonsunlimited.com/hub...934#post596594

I discovered at least 2mm clearance between flywheel and bottom of the rotor, i.e., housing of starter clutch.



I definitely remember that 120nm effort when tightening rotor nut, checking one-way spin of flywheel and seems that definitely missed checking clearance around it..

In manual there's no indication what is maximum clearance between flywheel and rotor.
Seems that on assembly, "by default" rotor moves all the way back to the tapered end of crankshaft and therefore leaves no or almost no place for flywheel to slap around.

A). Is there known such type of wear / deformation which prevents rotor to be placed on the proper location back on the crankshaft? visually it was all good, just another thing to suspect is key, but I can't remember any condition when it interfered assembly in such way.

Well, first thing is to reinstall rotor in the better way.
As I remember sometimes rotor removal includes direct / slide hammering and B). is it ok to try hammer it inside? If yes, are there any ways to define / explain, how much force is safe to knock it deeper on the crankshaft?

C). could anyone say what is maximum safe clearance around flywheel, preventing it to slap around?

D). If I still will not be able to move rotor on proper location, could adding / replacing washer next to the flywheel be a solution?

Well, thanks for attention / any *).

remounting the rotor will not change anything, there's no way that it will cancel such a large gap. i dont have the part drawing in front of me, but any chance you forgot a washer behind the gear wheel? I always remove the starter clutch, gear and elecric starter in my supermono motors, so never pay attention how it is put back...

in any case, i dont think thats the source of your noise.... would suspect the tensioner not working for some reason due to wrong assembly or something.
i.e., noise coming from loose timing chain slap

turboguzzi, thanks for opinions.
suspecting chain really makes a sense, as it related to engine acceleration/deceleration (slightly decrease/increase)
but...
just removed rotor. washer was on its place. tensioner is working also, chain was not loose and during re-installing tensioner, I heard few clicks and one more when I rotated crankshaft.

only suspicious thing there was free play of front (passive) chain guide -
it doesn't seem broken or so, but still has some movement, and sometimes chain as well, on the front side -


so far, I've got three possible reasons
- maybe bent / worn front chain guide, if such free play is abnormal.
- increased flywheel / rotor clearance
- somehow displaced chain gear on crankshaft (is that possible?) which caused this gap and new chain doesn't tolerate that ~1° bend..

it's hard to see from video, so maybe take a pic, but the chain guide looks too thin where it sits in the cavity
could it be that plastic got broken and you have only the internal metal blade touching?


too me it looks like it should be thicker at the end which fills the cavity, see pic, i cant see it in the video

sorry for video quality, here's a better image -
(tensioner is removed to better access guide)
http://vardzelashvili.com/imghost/im...79_DSC0776.jpg
and full sized file here https://i.ibb.co/0sDz4F6/DSC0776.png

For me, there's no obvious signs of wear, and as I recall, about same was in the middle during assembly.
do this guides bend? all I've got for now is some free play in the cavity when tensioner is installed.

ok, looks fine to me. a tiny bit of free play in the chain would be acceptable, as the tensioner has little steps and between each it leaves a bit of slack.


really hard to diagnose what it is without being there and hearing..... are you sure it's not the drive chain or someyhing silly like that?

Well, whole story is that after replacing cam chain, piston rings and valve seals in the engine (first two oem, valve seals - athena), after first startup bike immediately started ticking, mostly from the lower left side, almost inaudible from the right.


anyways, still checked nuts /washers under clutch cover, everything was good there.

agreed with you, very often silly things are hardest ones to find, also understand the difficulty and limitations of support in such a remote ways, and again thanks for your time and input.

Tomorrow will try to find / prepare extra washer and place it behind flywheel, at least will extinguish that suspicious gap, who knows, maybe that's the reason...

Could it just be plain old piston slap?
Did you have the cylinder and piston meassured when it was apart?

happy ending
 

No, they were alright, steady on that 95ish mark. and sound also was much "gentle".
Well, today it was definitely the happiest day of this winter.
not (only) because it was the last day, but my guess about increased flywheel clearance appeared to be true and has already been solved :D

searched my stocks, then wandered in dismantled car's places, finally collected few different washers for crank (internal diameter should be 3cm, external 5cm but I think external match is not very essential, ~4 - 5.5 range seemed quite safe).
compared different options (single thick vs two thins) and finally one 4mm thick washer appeared to be winner (original is 2mm).

increased heartbeat, easy start and no more ticking, that was really great.

but there's still something to remember - seems that tapered end of crankshaft is no more very nicely tapered. visually it seemed all right, but with naked fingers I felt very slight imperfection at the end (where tapered end becomes equal to main diameter of the crank).
hard to say how it was caused - by age, too much force or cold winter, anyways, it was enough to create extra gap and seems like flywheel somehow started extra movements/vibrations.

Well, happy spring to all : )

Thanks for updating the thread, that really is an unusual thing, im glad you got it sorted.
Happy riding :scooter:

agree with jens, so unusual in fact that am asking myself if your rotor is sitting properly with this small bumps on the shaft. it should really make full contact with all the taper length, would use machinist blue to see if it's seating all along.

Well, with that nut off, rotor was sitting very firm, impossible to remove with the both hands. on the inside surface of rotor (mating with tapered end), I was unable to find such imperfections, but can't say that there isn't any.
Washer was in quite good condition, had just visual circular marks on the surface, no thinning or so.
Having break-in period since then, So far bike starts and runs well.
Using a machinist blue is good idea, have to try it on the next disassembly.

The Raptor 660 motors are kind of known to wear the crank tapers , so it's not unheard of with these big bore Yamaha's . May be more a case of not enough torque on the nut and the flywheel flexes slightly at higher rpms that wear the tapers. If the flywheel "locks" on the crank end fairly easy and requires to be pulled off the taper should be ok .



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