Rear transmission howling (help)  By  scooterglutton (Read 1,198 times)

Fix it now before doing more riding! I ignored a howling bearing thinking it was a howling belt, and, the failed bearing tore up the crankcase. See the vendors banners at the top of the page, one of them is sure to have the right bearings.

Actually I just thought of this, there's probably no way I'd see metal in the gear oil from bearings.  They are separated from the gear oil by an oil seal, wouldn't they be?  Scooters are new to me.

I am pretty sure it's the final drive as it only howls when the rear wheel is turning.  Of course there is also the clutch shaft bearing and 2 bearings on the intermediate gear, so I am thinking just get EVERYTHING, seals and all and do it all at once.  I found a supplier partsatv.com that has excellent diagrams and all the parts are listed (without part #'s on some), but EXPENSIVE.....unreasonably expensive.  I calledpartsforscooters and they didn't know how to look up the parts without part #'s.  Argh!
Here's the diagrams and part lists I found:

Thanks again, good information!  I believe the previous owner JUST changed the gear oil cuz it looks quite clean.  (maybe he knew the problem and this is why he sold it) So I have no idea what weight it is, or if it was loaded with metal when he changed it.  I tried calling him and guess what???  "No longer in service"  ARGH!!!! Of course he didn't mention that he just changed it.  I didn't really do my diligence checking it out.  It was night time, very cold and I let the friend who gave me the ride to go look at it talk me into just getting it.  "For $800, so what if you have to fix some ."  I was like, ya!  Sure, I can fix anything anyway.....of course I should have known better.  My friend doesn't have to search for parts and PAY for them and have to rely on it EVERY DAY to get me back and forth to work etc.  I got hosed and now I know it.  The scooter has been treated ROUGH.  It appears to have been completely disassembled at some point because many fasteners and clips are missing, it's been repainted, the solenoid has been rewired and replaced and is just bouncing around next to the battery.  The tach only works about 10% of the time and it bounces around. 
Oh well, I will learn a lot working on this and a lesson in buying used Chinese scoots.  I am very knowledgeable in auto repair and parts, most of my working life spent managing repair shops and parts stores, so not much scares me....but it makes me a little TOO bold...I tend to always tell myself, "I can do that".  Which is true, but I don't WANT to anymore.

 I have found some EXCELLENT information from this site with Yamaha part #'s and diagrams: partsfinder.onlinemicrofiche.com/yamahagenuineparts/showmodel.asp?make=yamahasc

BUT, this is all for a 2005 and newer YP400.....but everything LOOKS the same.  I'm gonna try cross referencing some of the KNOWN part #s I found for the Linhai/VOG 260(170mm) and see if they cross to the part #'s on the Yamaha parts website.  If they do, this would make it much easier to find higher quality parts for it (the engine/trans anyway).
 partsatv.com Has diagrams w/part #'s, all chinese parts though and his prices are astronomical.  He appears to have a warehouse FULL of these parts in TX. But, I'd rather cross them and get cheaper, better bearing parts from NAPA/Advanced.

Another thought I am having now is that this could be the gears themselves.  I need to stop conjecturing and searching for parts I may not even need and just tear it down.  But then I'm walking for however long it takes.  I don't want to buy ALL the parts for the tranny, that would cost more than what I could buy another bike for, LOL!   I can't sell it without fixing it for what I paid, I wouldn't try to push it on anyone else like this, I just don't do that.  So, come what may, aside from a catastrophic failure....I'm gonna learn this thing and do whatever it takes. 

since you seem to have good mechanical aptitude, this shouldn't be much of a problem for you.
since the final drive housing is aluminum, i just hope the bearing mounts aren't reamed out.
if you find that to be the problem, then look around for a blown 257 and salvage the CVT case.
speaking of aluminum, take it easy with the scrapers and sand paper (and the torque)

there are only 3 sets of bearings in the final drive, 2 for the clutch shaft, 2 for the countershaft, and 2 for the wheel axle.
on my bike, all of these are open race except the wheel side of the wheel axle.
the countershaft bearings were needle, the other 4 were ball.

these drives are vented, so make sure you don't pinch the vent hose on reassembly.

Awesome, thanks much for the help! 
Having Honda #s might help out a lot.  I hope the gears and axles are OK too.  We'll see!
I am probably gonna have to buy a bicycle to ride back and forth to work for a few days while I tear this down, then wait for parts.  I will have to ride a few more miles unfortunately until next payday, so I can get this handled.  Thanks again and I'll keep this updated with what goes on. 

UPDATE:
Tore it down with relative ease.  Was VERY happy to see that the culprit was only the clutch-shaft bearing on the left side (in the cover).  SO, got a SKF bearing from Napa and dropped it off just a iminute ago at a local shop to replace the bearing for me.  I'd like to be replacing everything wearable in there, but it'll have to wait.  Money is short and I can't be without wheels without completely messing up my life.  The outer bearing in the clutch is starting to feel a little rough, but I'll be replacing the whole assembly within a month or so...I am quite relieved that I can at least take care of the terrible howl and potential BIG problem today, without interrupting my regular routine too much.  I'll definitely update my progress with this scoot as I plan to keep her for a while.
BTW, the part # for the bearing I needed doesn't match ANY of the diagrams I have got...my diagram says 6025c3, but the # on the bearing is 6205/p53.   Strange huh?  I thought all of these 257cc Yamaha clones would be the same....maybe not. 
Anyway thanks for all the advise, I am less intimidated now, knowing I didn't have to call China for parts!

Now I can worry about the tire I need, the leaky rear brake hose (not bad, YET), the rear brake pads, both master cylinders (sight glass is turning to mush, why do all the Chinese scooters do that? Cheap acrylic/plastic I guess), an airbox and hose (might make my own, custom intake. I can't seem to find one like it anywhere, they are different than all the other 260cc one's apparently) A new windscreen (mine's hard to see through with all the spider-cracks, once again, cheap plastic), a new intake elbow etc etc etc....this is SO much fun!  (total sarcasm when I say that)  But really, my life is so boring without something to fix all the time.
Thankfully (knock on wood) the motor is clean and has no issues. 
My temp gauge never gets over the "C" on the left side, but it does move.  I almost wish this thing were air-cooled like my old 50cc was...so simple and less to worry about.  But I wanted something bigger and faster and worthy of longer trips so.....I ASKED FOR IT!   I am a glutton for punishment, hence my name.