While I'm looking for some NOS parts to start back on the SL100, I decided to rebuild the engine in the CB400F. The cam chain tensioner was toast and you have to split the cases to repair it.
I've decided to tear it down in the frame because it's too heavy for me to lift it out by myself.
I have cases ready for the rebuild.
The opening for the countershaft has scratches in it. They don't go all the way across but I'm thinking I could fill them in. Do you think that is necessary or can I ignore them?
Lots of signs of poor maintenance on the bike. It has the wrong clutch cable--it doesn't even screw into the engine case.
But it does look like someone put a new rotor and stator in fairly recently.
The carbs worked fine, but they really could use some cosmetic work. I'll fix the corrosion issues and replace the o-rings inside.
Once I got the cylinder head off, I could see the cam chain was very loose, I could hear it rubbing on something inside when I turned the crank to pull the cam chain sprocket. I could also pull it off the sprocket with my finger. The tensioner definitely isn't working. Both the cam tensioner and guide are very worn.
I got 7 out of 8 exhaust studs easily and the last one broke. Figures.
The cylinder is stuck, it's gotta be at the base gasket because it turns over very easily. I quit today before I broke something from impatience.
I smacked the bottom of the cylinder with a cold chisel ground down to approximate the shape of the cylinder. It just took a light tap and the cylinder was free. However, this was as far as it would go. The pistons were free, but it felt like the middle studs were holding it up. After half an hour of reefing on it, I got a wooden drift and smacked it on the bottom a few times.
After a few taps, this fell out of the cylinder.
It's some kind of plastic putty that was put into the slot in the front of the cylinder where the studs pass through the fins. You can even see the the person's finger prints who put it there. Nothing about it in the manual. A few taps with a small screwdriver and it was out and the cylinder was free.
This was where it was, four of them.
Now I can lift it out of the bike and put it on the bench.
I measured the bores and all are in tolerance so I'll just have it honed. The rings look good and it wasn't burning oil so I'll reuse them. The max outside measurement is 2.012.
Cylinder measurement at the top Measurement at the bottom
1 2.006X2.006 1.994X2.004
2 2.007X2.006 1.994X2.009
3 2.008X2.007 1.986X2.005
4 2.005X2.009 1.996X2.007
All four pistons were above the 2.002 minimum.
I'll split the cases and move the transmission to the new cases and then check the crank and main bearings with plastigauge. The head will go to the machine shop for a full inspection and minimum of new valve seals.
I've decided to tear it down in the frame because it's too heavy for me to lift it out by myself.
I have cases ready for the rebuild.
The opening for the countershaft has scratches in it. They don't go all the way across but I'm thinking I could fill them in. Do you think that is necessary or can I ignore them?
Lots of signs of poor maintenance on the bike. It has the wrong clutch cable--it doesn't even screw into the engine case.
But it does look like someone put a new rotor and stator in fairly recently.
The carbs worked fine, but they really could use some cosmetic work. I'll fix the corrosion issues and replace the o-rings inside.
Once I got the cylinder head off, I could see the cam chain was very loose, I could hear it rubbing on something inside when I turned the crank to pull the cam chain sprocket. I could also pull it off the sprocket with my finger. The tensioner definitely isn't working. Both the cam tensioner and guide are very worn.
I got 7 out of 8 exhaust studs easily and the last one broke. Figures.
The cylinder is stuck, it's gotta be at the base gasket because it turns over very easily. I quit today before I broke something from impatience.
I smacked the bottom of the cylinder with a cold chisel ground down to approximate the shape of the cylinder. It just took a light tap and the cylinder was free. However, this was as far as it would go. The pistons were free, but it felt like the middle studs were holding it up. After half an hour of reefing on it, I got a wooden drift and smacked it on the bottom a few times.
After a few taps, this fell out of the cylinder.
It's some kind of plastic putty that was put into the slot in the front of the cylinder where the studs pass through the fins. You can even see the the person's finger prints who put it there. Nothing about it in the manual. A few taps with a small screwdriver and it was out and the cylinder was free.
This was where it was, four of them.
Now I can lift it out of the bike and put it on the bench.
I measured the bores and all are in tolerance so I'll just have it honed. The rings look good and it wasn't burning oil so I'll reuse them. The max outside measurement is 2.012.
Cylinder measurement at the top Measurement at the bottom
1 2.006X2.006 1.994X2.004
2 2.007X2.006 1.994X2.009
3 2.008X2.007 1.986X2.005
4 2.005X2.009 1.996X2.007
All four pistons were above the 2.002 minimum.
I'll split the cases and move the transmission to the new cases and then check the crank and main bearings with plastigauge. The head will go to the machine shop for a full inspection and minimum of new valve seals.