The last major piece to reinstall on the engine was the valve cover. I was hoping to be able to dunk the whole thing into my 5-gallon parts cleaner bucket before painting, but it turns out that even parts cleaner freezes solid when it is left in the shed over the winter. I was forced to just use some de-greaser and Scotch-Brite pads to clean it up before painting.
When I originally obtained the 1981 Suzuki GS650L, the two pieces that had been removed from the bike were the carburetors and the valve cover. The original owner had planned to polish the valve cover, but it is not the right material for polishing. The carburetors were removed trying to get a shop to do the cleaning, but the quote was more than I paid for the whole bike.
The valve cover was a bit discolored to start:
With de-greaser and Scotch-Brite pads it was looking just a little better:
Similar cleaning and sanding was done with the breather cover and starter cover:
Right away, with a few coats of primer and paint, these pieces were looking much better:
After a quick double-check of the valve clearances, everything was put back together and torqued down to spec:
And now, as soon as it gets warm enough to get the Ducati Multistrada out of the shed and create some working room around the frame of the GS, it is time to get this engine back outside and get it back into the frame.
Previously I had run through the electrical charging system tests created by the group over at GS Resources as shown in this post: Electrical Charging System. The results showed that the charging system was running a little bit low and my decision was to replace the regulator/rectifier and improve some of the existing wiring connections which did show some improvement as shown in this post: Regulator/Rectifier Replacement.
At that time, I decided that the stator still had life and did not replace it, but now that the engine was completely torn down it was an opportune time to take care of this as well.
A new OEM stator is quite expensive which was another reason for not replacing the stator before, but there are a few options for aftermarket replacements. I chose a unit from Caltric.
While waiting for the new unit to be delivered, I was wondering about the plug that encapsulates the three wires and seals off the stator cover to the engine crankcase. I was wondering if I would have to figure out how to cut the old one off and reinsert to the new harness. I was happy to see that the plug was included, but then a little disappointed when it was not the correct distance between the wire sheathing for it to fit into the stator cover at the correct location. A bit of trimming of the sheathing and sliding the plug along the wires took care of that.
Once that was sorted, the stator and cover could be remounted to the engine with a new set of Allen head bolts.
The same was done for the clutch cover on the other side.
The valve cover still needs to be cleaned up and installed and then waiting for better weather to find out if these repairs have met the goals of restoring this engine.
In a continuation of the Part I post, I continued with the cleaning and polishing of the Clutch and Generator covers. The same procedure was followed as done in Part I.
Both covers were in pretty bad shape, but the generator cover was really washed out and oxidized.
A couple of hours later, both were looking much better.
Still a couple of things to do behind the clutch and generator covers before they can be reinstalled to the engine, but things are looking promising.
I started trying to improve the appearance of some of the engine covers today before they go back on the engine. I started with the smaller pieces of the signal generator cover and the secondary drive cover to see how the method would work out.
The first step was to pry off the old DOHC emblem and then hit the pieces with some Aircraft Remover to try and get through any clear coat that might still be covering the oxidized areas.
The Aircraft Remover and a bit of light standing started to make things look better right away.
The remainder of the work was a sequence of different buffing pads from Chemical Guys on the Porter Cable 7424XP random speed, orbital buffer and the Vintage Aluminum and Metal polishing compound that I bought at a local motorcycle show a while back.
I used the same polishing compound with the different buffing pads rather than one pad with multiple compounds. Each pad from Chemical Guys has a different cutting and polishing composition. It worked well, but I may try some different strength compounds as well on the bigger pieces.
As indicated in the Biker Wax directions, a lot of black residue was generated with the Vintage polish.
After going through the series of five buffing pads, both pieces were really starting to look good.
The new emblem really helps too. The emblem is just laying on top for now. These pieces should look really good along with the other covers once they get reinstalled to the engine with new Allen head bolts as well.
Thanks for looking.
One of the engine components that I did not look closely at in the original work was the cam chain tensioner. It is typically a device that once it is set, you never touch it again. Unfortunately, since the rear cam chain guide snapped at the interface location with the tensioner it appears that something was not set properly or became stuck. It is a very simple device so I went ahead and replaced the plunger and springs to make sure that everything was up to date after 37 years.
Nothing was obviously wrong with the original plunger and spring on the left, just a bit of wear on the plunger.
Once the new plunger and spring were installed, the plunger was compressed and the lock nut tightened to hold it in place before reinstalling it to the engine.
Once the tensioner is installed in the engine block, the plunger is released by backing off the set screw one half turn. The change in the main spring can be seen when the plunger is released on the right.
The cam chain tensioner operation can be confirmed by rotating the engine in reverse to create slack in the chain. The main spring will rotate to show that the plunger is moving to take up the slack. The engine should never be rotated in reverse again after this check.
With the tensioner working properly I could then confirm the valve clearances that I previously set. I was expecting the number 3 intake valve to have a different clearance with the valve replacement. The specification for valve clearance is 0.03 to 0.08mm and tends to get tighter as the engine is run and the valves wear. My original settings were at the higher end of the range and even a bit outside in the 0.10mm range.
Interestingly, everything was expected except for the number 1 exhaust valve. The number 4 intake valve went from 0.10mm to 0.12mm which I am ok with, but the number 1 exhaust valve was previously set to 0.12mm and was now reading 0.05mm. Still within spec, but not consistent with how the other valve clearances are set. In the previous adjustment I had changed this shim from 2.70 to 2.60 because it was under spec, 0.02mm clear. I decide to change again to a 2.55mm shim. The clearance with this shim is now 0.09mm which is in line with the other valves.
Now I have to figure out the best way to clean the remaining engine covers so that I can get this engine completed for spring time.
Dropping the cylinder head back on is straightforward. I just wanted to visually confirm that the timing marks on the signal generator were placing cylinders 1 and 4 at Top Dead Center before torquing down the head and installing the camshafts. With the timing mark aligned at T 1-4, everything was looking good.
Place the head gasket and cylinder head over the studs and then torque the head bolt in the pattern cast right into the cylinder head.
When I previously removed the valve shims and valve buckets, I placed them into an egg carton so that it was easy to keep track of which cylinder and which valve they came from. I am hoping that most of my valve adjustments after this will be limited to the number 3 intake valve since that was the only valve that needed to be replaced.
Now it is time to install the intake and exhaust cams and set the timing of the valves. The exhaust cam has 1 and 2 stamped on the sprocket as well as the threaded section for the tachometer reading. The number 1 and arrow on the exhaust sprocket are to be pointing forward and parallel with the surface of the cylinder head.
Once you have the exhaust cam aligned, the intake cam is installed so that there are 20 chain pins between the number 2 mark on the exhaust cam sprocket and the number 3 mark on the intake cam sprocket. A common mistake in this step is not starting the count of the pins at 1 and then ending up with an extra pin between the sprockets.
Once everything was tightened down I rotated the crank a number of times by hand to make sure that the number 1 mark on the exhaust cam sprocket and Top Down Center on the camshaft were coming back around to proper alignment and no sense of interference with the valves and pistons.
The next thing that I want to do now is to rebuild the cam chain tensioner. This is one item that I did not take a look at the first time around and suspect that it is a large reason why the rear cam chain guide broke at the point where it interfaces with the tensioner.
In the last update, I had completed the work of putting the crankcase back together and was considering re-mounting it in the frame before completing the rest of the reassembly. Of course, there was some frame painting that I wanted to do first and wasn’t getting to, so I finally went ahead with completing the re-build of the engine in the basement. Glad it worked out this way since it would have most likely made things more difficult to work with the confines of the engine in the frame and lower to the ground.
Next up was to reinstall the four pistons and get them reinserted to the cylinder block. Reinstalling the pistons to the connecting rods is pretty straightforward, just reinstalling the circlip to keep the wrist pin in place. Definitely want to block the hole below the piston while doing this. It would be a traumatic experience if you just completed reconstructing the crankcase and then dropped the circlip into the bowels of the crankcase.
Place the o-rings on each cylinder and the gasket on the crankcase and you are ready to go to reinstall the cylinders.
I started with the number 2 and 3 pistons thinking it would be easier to work on those with as much room as possible. Ring compressors were added to those two pistons and the cylinders lowered on to the pistons.
With those two installed, it gets a bit more fun trying to rotate the crank enough to raise the 1 and 4 pistons up while not losing connection to the 2 and 3 pistons.
And that is it.
I do have to admit to a few oversights in this process. First, the whole reason for the engine rebuild was to replace the broken rear cam chain guide. The first time I lowered the cylinders on to the 2 and 3 pistons I failed to make sure that the cam guide was in the cam chain tunnel. Cylinders back off. The next time, the 2 and 3 pistons pulled back out while trying to get the 1 and 4 pistons to rotate in. The third time I did everything very quickly, but then wondered why the cylinder was such a sloppy fit and realized I had left out the two locating pins between the crankcase and the cylinders. Fourth time was a charm and I am now a master at getting the pistons inserted to the cylinders…