Tale of Woe II: The Sequel

[BigTedSalad]

Just to update myself and anyone bored enough to read my posts here's where we are to date.



Looks scary to me but some of you spanner warriors would probably relish the challenge.

After all the horror stories of balance shaft problems I decided that I should check it out, rather safe than sorry. I'm happy to say that the woodruff key and shaft are as Mr. Yamaha intended. I have retorqued the nut and fitted a new tab washer so hopefully that's that.
So far the worst thing I have found is a timing chain I suspect of being very worn. I took the spring out of the tensioner and then removed it. I estimate that the plunger is out by 65-70% of it's range of travel so I've decided to change the chain. I did notice the sound that the guide blade made as it flapped around and it's very familiar. Is it possible that this was the clacking I heard and the chain was so worn as to throw the static timing out slightly?
I turned the engine back and forth a degree or two and there was a very slight clunk from somewhere around the bore. The barrel came off for a look but I can't feel any vertical movement on the conrod, just a slight clunk as the piston moves side to side on its bearing. Should this worry me or is it normal?

If you turn the volume up you may be able to hear what I mean:

http://youtu.be/y15rFw7N9u0

So, with the inspiration born of blissful ignorance and financial desperation, I intend to put her back together this weekend. From those of you who worship the Lord I would appreciate a prayer: from those of you who worship Mamon I would appreciate your spare change.

Thanks for reading.

[BigTedSalad]

In case anyone is interested I have only recently been able to get to grips with this, thanks to a snapped tendon in my shoulder.
In ignorance of what I was dealing with I dropped the engine and started to strip it down. The first thing I came across was this:



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In my rush to get the bike on the road I decided that the messed up piston must have been the problem so I bought a new one and had the barrel re-bored. It all went back together nicely and, eventually, started up and sounded like it should. I was one happy teddy until I took it out and the engine started to die again. It ticks over, revs freely and sounded great in the garage but, 4 miles down the road, nothing. It dawned on me then that the hissing noise I heard when I shut the engine down might just be the tank sucking air in so I tried to blow up the breather tube and nearly destroyed my ear-drums. Absolutely blocked, so a good wash out and a check of the filters is in order, I think.
Unfortunately, when it decided to misbehave on the open road, the engine started making a one-per-revolution clanging again so back to the drawing board. By a process of elimination the only area left to look in is the starter clutch. Holding a screwdriver/ear to the area sort of confirms it and the starter makes a few bangs and rattles occasionally. Anyone else with a similar experience?
In the meantime, I managed to pick up a complete, stripped, rebuilt and re-bored engine from an XTZ660 at a very reasonable price. I'm tempted to use this and strip the original on a bench, possibly even break it for spares. Any offers or interest?
Thanks for reading.

[BigTedSalad]

I got impatient and just chucked the replacement engine in. Started after a few minutes of jiggling with the carbs and putting a decent plug in it. It sounds good and will be back on the road later in the week, after I've finished tidying up the electrics and all the other bits that 13 years of bodging have produced. I'm struggling a little with the carbs; a previous owner decided to do his own plumbing on them and I can't get a decent diagram of how they should be. Can anyone provide me with a link? I've got a pdf of the xtz manual but the photocopy standard is a little poor.
Please look in the For Sale section if you want anything off the old engine. It does run, most of the bits are in good order but I don't have the time to rebuild it on a bench.

Thanks for reading.

[OLDMTNCARVER]

What are you looking for...
There is a view of the carbs in the parts book that shows the components with part numbers.
There is about fifteen (15) pages in the Service Manual (ENGINE 4NN / MuZ 660 E - YAMAHA)

Regards,
Robert

[BigTedSalad]

Thanks, Robert. I was struggling with the correct routing of the various pipes and the copy of the manual I have is poor but I think I've got the hang of it now. A previous owner has disconnected the vacuum tube between the two carbs which probably explains the poor running on over-run. The other pipes I was trying to figure out are, I'm sure, just the vent and overfill pipes.
Do you know where I might get a better copy of the service manual?

Thanks

[billr]

Do you know where I might get a better copy of the service manual?
Thanks

If you have a Yahoo account, try this Yahoo MZ Owners group
Manuals for the 660 motor listed in the Files.
Bill R

[BigTedSalad]

Thanks Bill, great advice. I joined, found what I wanted and I'm all sorted now.