Look what is finally back!
After 3 weeks of waiting,
that felt more like 3 months of waiting because I wasn’t able to ride my dirt bike
and it’s just sitting there,
my barrel is finally back from being redone.
The outside looks cleaner than the rest of the engine now which is going to be awkward,
but more importantly, the inside of the barrel is looking better than ever before.
3 weeks ago I embarked on my first-ever top end rebuild
and found something that slowed the process down a lot!
Nevertheless, I used that time to fix up other aspects of the bike
like the janky gear lever
and I also overhauled the drivetrain with new parts all around.
And if one good thing came about getting the barrel redone
it’s that the vapour blasting it went through
even cleaned the splooge out of the hard to reach places
like in the power valve linkage cover.
If you remember when we tore the top end apart to do our "quick" top end rebuild
I found a chip on the edge of one of my exhaust ports.
Which needless to say really ruined my day and the next 3 weeks.
But now that chip has been welded up and it’s been recoated in that
Nikasil coating so the whole thing just looks absolutely beautiful.
You can see the cross-hatching and I’d love
to just keep it here on the bench to look at every day,
but I think it might be a bit more useful back on the bike.
However, this is not what we have to do first.
If you remember that shift shaft has the mangled splines so we first have to pull the old one out
of that and put the new one in before we can start rebuilding the top end of the engine.
But can we also just take a moment to appreciate that when I made the
garage makeover video and built this shelving rack
all I had on it was two jerry cans because I didn’t have enough things to fill it up.
But yet it’s coming in very handy right now for all the parts that have come off
the bike and all the parts that are going to go onto the bike.
Because off to the side we have the tank, seat and plastics.
On the bottom, we still have our jerry cans out of the way.
On this level we’ve got bigger parts like carbs, silencers, pipes,
reeds aren’t that big and covers aren’t either but they get to live on this level.
The next one up we’ve got all our little parts that came out of the engine
that most of them are going to get to go back in there. Another level up we’ve got all our new
parts like a fresh air filter, all the gaskets we’re going to need, a piston, some coolant,
some engine oil or transmission oil, bearings and then the old gear lever looking very sad,
he’s going to be happy to retire.
I started by draining the oil
otherwise things will get messy one way or another
when we remove the engine cover and gear lever.
It's a bit strange removing the clutch-side engine cover
to get out the gear lever that's on the opposite side
but it's actually a very straightforward job.
So with the kickstart lever, brake lever and coolant hose out of the way
I could remove the engine cover without even needing
to remove the coolant pump or clutch covers.
And I made sure to keep track of where the different length bolts go.
For some reason clutches are always fun to play with, I loosened off the springs and
removed the pressure plate before loosening the clutch basket nut with my handy impact.
Which was one of the reasons I bought it in the first place.
And it’s actually the first time I’ve got to inspect this bikes clutch
and both the basket and plates were in better condition than I expected
which means one less thing to worry about at least.
Then out came the inner hub and outer basket to reveal the back of the gear lever we’ve been
looking for which surprisingly just slides out, not even a single bolt.
Okay, so these are all the parts that we’re going to need to replace the shift shaft.
So obviously we have the shaft itself with its fresh splines,
everyone knows you need a gear lever because the splines on that also got damaged.
We’ve got this beautiful Tusk one that’s black and blue anodized tip,
I’m probably going to regret this when the anodizing wears off
but it’s going to look pretty in the meantime.
Sadly, I didn’t get the matching brake lever but maybe one day.
In the meantime, it’s going to be a bit lopsided.
Then on the end of this shaft, there’s always a seal to keep oil in and everything else out
so we’ve got a replacement of that just to be safe and while we’re in there
and the same with the spring.
So you might have noticed that your gear lever always returns to its natural position
and that’s the spring’s job so we’re gonna replace that as well just to be safe.
And then this green gasket didn’t fair too well when you take it off so we’ve got a
replacement for that. It’s even genuine Yamaha, way nicer than this green nonsense in my opinion.
And with both the shafts on the bench I found another reason to replace it.
You can see the gap between the shafts growing and shrinking as I spin the old shaft
which means the tip is not just mangled but also bent.
I’m glad I decided to replace it.
On the other side the old seal just pops out
and then I used the back of a screwdriver and hammer to seat the new one.
The new shaft first needed plenty of lube, a spacer, that new spring we bought
and a washer before it could be slid into place and the disassembly process could be reversed.
And I just broke my record for the cheapest part I’ve ever bought from Yamaha.
If you were observant you might have noticed that when I was taking the nut off the clutch basket
that the little tabs that you bend over on this lock washer were missing.
That kind of worried me.
And luckily I don’t think they broke off in the engine because there’s no sign of them.
I assume the last owner was just lazy and didn’t bother
replacing this because you are only supposed to use it once.
I’m not going to lie I was going to use it again but luckily Yamaha had a couple in stock.
With that problem now fixed I moved on to the more nerve-wracking job of reassembling the top end.
The cylinder needed to be stripped to be redone
so the first thing I had to do was reinstall the head studs.
I struggled to remove them but by this point, I had the technique down.
Sandwiching two nuts together and using the top nut to tighten the studs down.
Next, the power valve could be reassembled
and that new shaft and new seal put in
that hopefully means the end of splooge pouring out the side of my engine.
And then over here I even have a laptop with my service manual on.
So that if I need any diagrams or layouts, any torque specs because
a mate of mine even leant me a torque wrench so that we can do things properly,
we have all the information we could possibly need.
I’m pretty sure I went overboard with the premix
but better to have too much than too little
And since I had a complete gasket set, everything got fresh gaskets or o-ring
and by this point, I even had a pretty good understanding of how the exhaust valve works.
I’m going to upset a few Germans with my pronunciation
but I opted for a Wossner piston kit because I found plenty of good
things about them online like their coating
and the cylinder was matched to this piston hence the job number on the top of it
which I did clean off with a bit of petrol before installation.
To check that the ring end gap was in spec
the cylinder needs to be coated with some premix
and then the ring is put into the cylinder,
squared off with the piston
and then the gap can be measured with a feeler gauge
which to my relief were both in spec because I didn’t fancy filing them down.
I’m warning you now that’s there’s never any
footage of me actually getting a circlip seated in the piston
because it’s such a fiddly job that I eventually just ditch the camera
but which with one side in the rings could now go on and be positioned in the right orientation.
The new small end bearing got lubed up
as well and placed in the conrod
followed by the piston going on and the gudgeon pin being slid through
with more missing footage of the circlip installation.
Compressing the rings with one hand while making sure they’re in the right orientation
and sliding the cylinder on with the other hand was actually easier than I expected
and rather satisfying to watch.
However, not as satisfying as testing to see if the piston moves up and down smoothly.
That I could watch for hours.
I mopped up the excess premix on the piston before greasing up some o-rings
to keep them in their grooves while I put the head back on
and tightened it all up in a star pattern.
The little things like the reed cage,
coolant hose,
carburettor and engine mount
were then easy and stress-free to install
compared to the internal stuff that I’d never done before today.
Finally, it then got a fresh spark plug,
some new coolant,
fresh transmission oil,
a new air filter and even a new kind of air filter oil
since I’ve been using the spray-on oil and don’t think it’s as good as the real thing.
And outside it went for its big moment.
You can tell I’m somewhat ambitious about it actually starting because
I’ve half kitted up so that on the off chance,
well, we’re going to be positive,
when it does fire up I can actually get on it,
go for a quick ride and get it up to temperature so that we can do its first heat cycle.
I’m not going to do a very serious break-in just do about 3 heat cycles.
Try run it in fairly gently but still varying revs but it’s not going to be too scientific.
So a part of me is really excited because I get my bike back,
a part of me is terrified on the off chance that it actually blows up,
because after all I did the work on it,
and a part of me is actually disappointed and sad because I really am going to miss
having a project bike. I’ve learnt a lot and this has been so much fun.
And I might just be procrastinating because I’m nervous now.
Okay, here goes nothing.
Fuel on.
And I have cranked it over with my hand, I thought it had compression before this
but now it really does.
Do you think I tightened all the bolts?
Okay, first of all I completely forgot how much dirt bikes actually are,
why didn’t anyone tell me?
And secondly, it runs absolutely beautifully.
I’m so relieved that it started up on just the second kick
because a part of me really thought it would never run again.
I couldn’t tell you if it makes more power or not because I
wasn’t pushing it hard obviously on its first ride, still trying to break it in a little bit
but we’ll do another few heat cycles and get it to a track ASAP.
I’m chuffed with that!
But anyway, I got it to the track just 2 days later
and got to feel if the engine was any more powerful
so subscribe to my second channel so you don’t miss that.
And this is not the last massive upgrade I’ve got planned for the YZ.
In fact, the box with the coolest upgrade it could possibly get is already sitting on my desk.
But ultimately it feels like a new bike in terms of shifting
with its new gear lever parts and chain and sprockets
which is exactly what I wanted.
It’s confidence-inspiring to know more about my engines health and how it works
and this has made me want to dig into the bottom end to learn more about that…
just not on this bike because now I want to ride it.