Looking at the clutch, I see that the clutch spring retaining nuts are screwed all the way in and the adjuster screw is all the way in. Ether the plates are worn past service or the springs are sacked. When I measured the springs, they are about 3/8 inch shorter than original, so they need to be replaced. The clutch plates are within the wear limits.
I remove three slotted retaining nuts, the pressure plate and the clutch plates from the clutch basket. This exposes the clutch center retaining plate.
I use a special puller to remove the clutch center It fits over the three studs and the center bolt pulls it off the clutch hub.
This exposes the inner clutch basket. Behind them is the mainshaft with the 20 roller bearings that support the clutch basket..
I previously removed the alternator from the primary side of the crank shaft (on the left in the picture above). So I can now pull the primary sprocket, primary chain and clutch basket. The roller bearings will fall out as I do this, so I go slow to let them fall to the bottom of the engine housing so I don't lose any.
The primary chain tensioner is the black curved shape.
I use a puller to remove the clutch hub. The clutch hub is keyed on the transmission main shaft.
The roller bearings can wear. I measure them and find that they each has worn about 0.015 inch, which when multiplied by 20 roller bearings, is too much wear so I will replace these with new roller bearings.
In an earlier post, I showed how to remove the heads. In this post, I remove the cylinders.
At the base of the cylinders are the studs that go through the base of the cylinders. Nuts secure the cylinders to the engine case.
I pull up the cylinder barrel to slide them off the pistons. As I do this, the cam followers are exposed. While holding the barrel, I slide the cam followers up into the recess..
As I get close to removing the cylinder I don't want the connecting rods to strike the edge of the engine case. Nicks in the connecting rod become a stress concentration point and can lead to cracked rods.
I use some wood blocks to hold the pistons vertical and to keep them from bumping into the engine case. I carefully remove the rings and then insert them about half way down the cylinder bore to check the ring end gap. Using my Number one eyeball I can already see that these gaps are too large. When I check with feeler gauges they are about twice the allowed maximum gap of 0;013 inch.
By the way, this engine has had metal moths inside as evidenced by the chunk missing from the left piston skirt. Hmm, wonder where that went?
We have the engine in the stand and are going to go through it to do a rebuild. Here are the pictures of the engine before we start.
The first order of business is removing the head. First, remove the six (6) bolts holding the valve cover on..
Now that the valve gear is exposed, I can remove the rocker arms from the head.
Remove the bolt on one side and then tap the rocker shaft until the spindle is exposed on the other side of the shaft.. When removing the rocker arm shaft, there are springs and washers on the shaft, so take note of the order of these as you remove the shaft from the rocker arms. Also, mark your rocker arms and shafts "Intake" and "Exhaust" so you can easily put them back where they belong when you reassemble the head.
Now I can remove the rocker arms and the push rods. Note that the push rod lengths are different for the exhaust valve rods and the intake valve rods.
The four head bolts next to the valve stems are removed next. You can see them in the picture above. There are also two nuts beside each spark plug that are removed. When these are removed, you can use a wood block with a hammer or a rubber mallet to tap the head to shear it from the head gasket and then the head comes off.
With the head off, you see the tops of the pistons and the copper head gasket. And, turning it upside down, the valve faces.
Next, I'll post a blog about removing the cylinders from the block and the pistons from the connecting rods.
Welcome to our page of blogs for the Do-it-Yourself (DIY) owner of vintage Triumph, BSA and Norton bikes. As we get projects in the shop, we will choose some and show you how we do the work. If you want to work on your bike yourself, then this material can give you a good idea of what's involved. Although we can't provide individual consultation about your project, feel free to post comments and questions on these blog posts.