Eventually, I had my 3AJ shipped back to the depot in England so I again used Dale Booker, specialised motorcycle transporter to return it to Scotland.
Unfortunately, when I wanted to take it for a ride up the hills near me, it would not start. Even after many, many attempts.
It had been running the last day of the rally when I rode to Erfoud, so this was a big mystery. I changed the petrol and checked the spark plug was clean and getting a good spark but refused to start.
I bought a compression tester and the result was concerning. Only around 20psi!
After sharing my bad news on our SandRaiders WhatsApp group, Nigel suggested I try a leak-down test.
This meant I had to buy a compressor and a >£100 gadget from MotionPro. Eventually, I gave up on trying to set the tool to see what % was leaking and just listened for air escaping.
Anyone want to buy a MotionPro gadget?
At first it appeared that air was leaking from the inlet valve which seemed a little strange but I was relieved it wasn't from the crankcase, as that would have meant piston/barrel problems.
After reading the workshop manual and getting advice, I tried rotating the crankshaft 360 degrees to make sure it was on the compression stroke, and checking the valves had a little clearance (I had removed the rocker cover at this point) only to find air leaking from the exhaust valve.
Either way, I decided to remove the cylinder head and take a look at both valves. Of course, I also had to buy a valve compression tool, so I ordered one from Amazon, only to find it too small. Eventually I found one that fitted in my local Machine Mart.
Well, all of the valves looked to have significant pitting so I decided to lap (grind) them all back in. I had to buy grinding paste and lapping sticks as the last time time I had done this was on my T140V in 1983.
This of course took a lot of time and was quite tedious, so I would lap them with the cylinder head on my lap whilst watching YouTube videos on valve lapping...
I was quite shocked at the amount of carbon on the piston but was pleased to see honing marks on the inside of the barrel, which suggested it had had a rebore and new piston a few thousand miles ago.
I decided to order new valve springs from Fowlers as the old ones were outside the tolerance levels.
I re-fitted the valves using a cylinder head stand as I was really struggling to hold it securely enough to get the valve collets back in but forgot to change the valve stem seals.
I was a bit worried my lapping skills were substandard and didn't have enough time to take the engine apart again if it didn't work, so I took the head (and new valve stem seals) to my wizard of a motorcycle mechanic, Mark 1 in Edinburgh.
I cleaned the piston and cylinder head carefully (I had leqrned a lot from my YouTube Lapping) and reassembled it using the workshop manual downloaded from this site.
I was a bit concerned that the camshaft marks were not clinging correctly, and to avoid the chance of another rebuild, I called Mark to ask his advice. He reckoned camshaft drive chains stretch and you need to align the marks that would recognise this.
After reassembling the cylinder head, it was time to refit the cards. The inlet rubbers had too many cracks, so I decided to replace them. Rather than pay a fortune for Yamaha OEM inlet rubbers, I decided to buy a pair from
www.Kedo.com.
When they arrived, I discovered that the grooves the o-rings sit in were outside tolerances. One in particular was so deep, I doubted the o-ring would seal correctly. Luckily, I found a thicker o-ring in a box of spares, so I refitted the carbs.
I was a bit concerned that as the barrel and cylinder head had lost its black paint this might have led to the engine overheating and contributed to the valves burning. I had been especially careful to set the valve clearances correctly.
I had not yet changed the oil, so I decided to remove the clutch cover to check the thickness of the spare friction plates that had been fitted in Merzouga. Unfortunately they and the springs were on the limit! I started to rebuild the clutch, only to have two of the spring retainer bolts snap their heads off!
Luckily, I was able to remove them without too much drama but the gasket I had was for the alternator! So I toot suite'd it back onto the Fowlers website to order new springs and friction plates (the steel plates were fine), and a clutch gasket.
Unfortunately, the friction plates were not in stock and had to be brought over from the EU. I decided to use instant gasket to seal the clutch cover and top up with 20/W50 oil...
Eventually, the time came to see if the 3AJ would start. I only had a week before Dale was due to transport it down to the depot (of course I had signed up for SandRaiders 2024). Well, the bike started on the second push of the button and I was estatic! There was a lot of smoke coming from the new exhaust and engine paint, so I had to exit the garage until if faded.
The engine came off choke so much more quickly then before and the bike started pretty much first time after that. I did take it for a test ride around my neighbour hood and found the gear lever to be very stiff. This was because I used instant gasket instead, which compressed the gear selector shift.
I decided I'd have to lay the 3AJ on its side and fit the new friction plates and clutch gasket in Agadir...
Which will be tomorrow
