Casting a gimlet eye on the large blob of snot on my rear fender asking to be sanded down, I shudder and turn my attention to the motor.

I am reaching a point in the restoration where you start to run out of steam and have to force yourself to continue.  It happens in any restoration.  It will pass.  It is because I thought I had just about completed the bodywork, just primer, colour coat and clearcoat to put on the rear fender;  only to be confronted with the stretched metal under the tail light bracket.


I decided to tackle the generator side first and set the points...

The left cover screws were loose, so the seller had been in there.  He mentioned it was a non runner when it came into his possession.
Pulled the rotor off and yup, the points and condenser were new.. And of unknown provenance.  I looked for the makers mark on them and found nothing.  Looks to be cheap n cheerful.  It did start and run though.  I would have liked to see a quality makers mark on them, but hey ho.  The cap does say it is japanese though.

New points and cap..


I removed the stator to get to the left crank seal to discover it was very poorly fitted.  Looks like it had been accidentaly  knocked in on one side or had been replaced very poorly.
I do not know why because the seal lip appeared worn as if it was the original.

Seal dished, dented and not fitted squarely into the seal location.  Hard to see on the pic.  Far more pronounced in real life.


Opened the packet of my so called quality brand seal kit and came to fit the seal.  Inner lip greased and both seal outer and seal location bore given a good squirt of GT85 to lubricate them.

A quick word in general about oil seals while I am here.  Rubber backed seals should be fitted with a lubricant, never dry.  Metal backed seals should be fitted with loctite....unless the manual says different.  Some metal backed seals have a teflon coating that do not require loctite.  However, with these, it is not a disaster if you happen to loctite them, unlike rubber ones... 

Back to the tale..  I fitted the seal on the crank and put the old seal over it to use as a mandrel to drive it home.  Started to drive it, ensuring it was going in square and noticed the outer rubber coating was rucking up and the seal was not sliding into place.
On examination, it is obvious the seal is slightly too large for the bearing location bore.  It was the right size seal, but the manufacturing tolerance made it too large.
To continue fitting the seal using brute force is a foolhardy option.  It will become mishapen and the outer sheathing is already damaged.  Not great for a critical seal.

No choice but to order genuine seals.    Once again, I cut corners to try keep the spend down and got burned.

Genuine seals you know will fit.  Aftermarket is something of a lottery.

Seal sheething damaged due to being slightly too large for the bore. If you see this happening, stop immediately.  The seal is not correct and will become misshapen if you continue.  It may look good from the outside, but the lip will not address the shaft at the correct angle inside as the metal carrier will cone.

This problem is surprisingly common.  I see it often at work.  ZF transmissions are notorious for slightly undersized seal locations that will not accept non OEM seals.


New genuine seals ordered and job stopped...




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A post dedicated to one small, very low cost/ skill, but essential modification.

As you are probably aware (for those new on here) I was responsible for a large off and on road motorcycle fleet at a large motorcycle activity center.

On that fleet we had 8 RT100s that ran 7 days a week and 360 days a year, often operating up to 6 hours a day.

The mod I speak of increased the service life of the components by a factor of five.

​​​​​​On the earlier DTs, the RTs and TYs there is a remote gearchange chamber that due to running through mud constantly and getting regularly pressure washed, soon filled up with mud.  This wore out pivot shafts, outer covers and even crankases very quickly.

In addition, since yamaha left the chamber dry, any lubrication on the shafts and mechanisms dried out, also resulting in wear.  I know I am speaking of extreme conditions and abuse, but there can only be good in carrying out this simple mod.

It keeps out moisture and dirt,  and oil suspended in the soap wicks into the shaft pivot housings and the mechanism ensuring constant lubrication.

And what is this 10 minute marvel?

Ensure you pack the chamber with lithium grease.  I just did on the little un.  It will never wear out the crankcases or outer cover during normal use.  Remember to leave some space for the grease to expand into when the engine gets hot.

 

Bugger.  I am going to have to pull down the motor.  I really, REALLY did not want to put so much effort into it.  I was looking at new rings, probably new clutch plates and new seals.

I set up the timing and put the rotor back on without incident and drained the tranny oil.  About 200cc came out, not the expected 600 or so, and that that did emerge was badly emulsified.  Aw crap, someone was careless with the hosepipe 40 years ago and the tranny has sat in water laden oil since it was put away.
Hey ho, the bearings still felt smooth.

Then I removed the clutch cover to change the crank seal and look at the stuck clutch plates.
My good god....

It was obvious where the missing 400cc of oil was.  It had turned to sludge and was stuck to everything.

Can anyone tell my why the plates had stuck?  What a mess.  1976 motor oil and water that came from the tap when flyaway collars, platform shoes and flared pants were the vogue.


My troubles were just beginning.  I was not anticipating the next problem at all.  The cast iron barrel had rusted solid onto the studs and I do mean solid.  It did not move upon receiving the usual gentle tap with a rubber mallet.
Three hours it took to remove, involving heat, prying with tyre levers, using drifts, penetrating oil and more heat.  All the while, the water in the emusified oil was breaking down and oozing out over my 1ft x 2ft working space on the bench.
I used up about 5 j cloths just mopping up the mess from the worktop as it was breaking down.
Not a happy bunny.

Finally barrel was off, it had fought for every millimeter of stud length. 
So put barrel aside and gazed in horror at the rust and dirt particles absolutely covering the crank, covering the main bearing oil ducts, all over the big end and in the bottom of the case.
That put the lid on it. 
The prospect of rusty bearings in the tranny and dirt in the crankcase / down the bearing oil ducts made pulling it all apart a necessity.
Feck it all.

Time for a bath to stop the oil breaking down and continuing to make a mess.  Afterwards it was brought up to working temp with a heatgun to dry out the water left inside.  The thin film of oil spread throughout the internals should prevent any further rusting.


Such are the slings and arrows of outrageous fortune.  Fear not, i tell thee, I will take up arms against this sea of pestilence and trouble.

Only progress made this week is the finished generator cover.




 

Clutch cover cleaned up and painted.  New oil seals on pump shaft and kickstart.
oil tank delivery pipe is new but I need some 3mm tubing for the injection line.

Thinking of stripping the motor at work, so much easier than doing it at home and any rusty gears ect can be shot peened.

Did I ever mention how lucky I am?  Without bad luck I would have no luck at all.

Confirmed.  Motor has to go to work for disassembly.  I removed the left hand side stuff and the clutch.  Clutch nut is so tight its going to need an air impact gun to loosen it.

Disassembling the clutch proved "interesting".  In a  word.... Nope sorry I cannot think of one with enough gravitas to describe it.

Do you think I can re use them?

Yuck sure you can reuse them will add 10mph 

Took bottom end into work and got it stripped and cleaned at lunchtime.

I got away lightly.  Only one bearing was rusty and that was only the cage.  All the others, once cleaned out were fine and smooth running.  Everything is ready for putting together again now.

Encouraging signs.  No rust on gears, selectors or shafts.


Clutch basket needed beadblasting to get rid of the crud and corrosion but came out ok.  The only rusty part was the rear needle bearing for the main shaft.  New bearing is on order. 
CMSNL want £22 for one.  Having looked up the ISO number, I got a good quality one for £6.75.  ISO number for that bearing is TA1512Z.


Crank is in fantastic condition.  It cleaned up a treat..  And yes, this time I did remember to check it with a setsquare.

 

Amazing luck!  When I saw that clutch I was expecting the worst...  I've had engines apart where the area under the clutch cover looks really good but trans looks like it was stored at the bottom of the ocean!. 

Maybe because bike leans on the kick stand?

Your kickstand idea certainly has merit.  However, the bike leans to the left...
That is not to say it was not leaned to the right against a garage wall for 40 years..  It would explain a lot.

I have made the decision to replace the mains even though they look and feel ok.  With the motor stripped as it is, it would be extreme penny pinching not to.  All for the sake of a tenner.  


You know what my luck is like...

Tomorrow the barrel is going in to work for beadblasting in prep for paint and I will stick one of my bore gauges down it to check for ovality.  I noticed some scoring on the bore below the exhaust port, not too bothered about it, the bore is clean above the port;  just need to check wear.  It is still on the standard 52mm bore.
I will be replacing the piston too.  I noticed quite a lot of heavy scoring and galling on the exhaust port side skirt.  Looks like a cold nip. 
If it was owned by kids as I believe,  I bet it never got a warm up before wide open throttle.
Strange thing was it was very mechanically quiet when I ran it.  Maybe due to the cast iron one piece barrel.

Hey ho.  And I thought it was going to be a cheap project.

What I meant on the kickstand was the one I've seen with rusty trans when the clutch looks good might have been from the kickstand lean...  which is why I expected yours to be worse. 

You're very lucky.