Clean and Polish – Part II

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.

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Clean and Polish – Part I

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.

Cam Chain Tensioner and Valve Clearance Check

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.

Cylinder Head, Cam Shafts, and Timing

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.

Cylinder Re-installation

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…

Valve Installation

The cylinder head has been off the bike for a while now to determine the reason for the loss of compression in the No. 3 cylinder. In previous posts about this issue, Valves, it was determined that the No. 3 intake valve was bent when the cam chain guide broke and the timing jumped. Now that the cylinder head has been cleaned and painted it is time to reinstall the valves with a new intake valve ready to go for the No. 3 cylinder.

The first item was to install the new valve stem seals on the eight valve guides.

I used a 10mm socket on a hex driver handle to push the seal on to each valve stem to reach down to the valve guide and not push on the seal.

From previous work cleaning the combustion chambers with the valves still installed it was confirmed that the intake valve in the No. 3 cylinder was not seating properly since the cleaning solution was leaking past the valve and coming out of the intake port. I wanted to do something similar with the install process to make sure that the valves were seating properly, but did not want to make a mess of the newly painted cylinder head. I tried shining a flash light through the intake and exhaust ports which showed very clearly if the valves were seated properly.

As a worst case scenario, this is what was seen with the bent valve in the No. 3 cylinder. The intake valve is to the top side of the picture.

Of course, I can’t show a picture of a correctly seated valve, it would just be black.

All in all, the four exhaust valves seated very well as is and the 3 existing intake valves were also pretty good. A little light was escaping on the intake valves, but light pressure on the valve corrected that. Much less pressure the the valve springs will exert to hold the valves closed. The new valve, as expected, needed a little more work to seat in the worn valve seat. A few turns  of the valve with same lapping compound and lapping sticks did the trick.

To complete the valve installation it was then just the repetitive process of installing the springs, spring retainers, and compressing to install the the cotter halves.

Getting closer to putting it all back together!

Finishing the Lower End

The engine rebuild for the 1981 Suzuki GS650L is starting to come together and the parts bin is starting to empty out. It is great to be able to get the original shop manual for a bike that is over 30 years old, but the photos taken during the tear down are invaluable. The old grainy, B&W photos of the 1981 service manual that were then probably and scanned to PDF are a little tough on the eyes.

Once the crankcases are back together, there are only a few big parts to reinstall before the lower end is pretty much complete. On the left side of the engine it is just the starter idle gear and rotor.

Before reinstalling the rotor, I did replace the 3 roller and spring assemblies of the starter clutch. Fairly cheap money to replace these components as the springs are barely more than you would find in a ball point pen. One of the original three springs was fully compressed in its slot, so it was probably a good time to take care of this upgrade.

The starter, gear position indicator, and stator will wait until the engine is back on the bike since most of these pieces are still connected to the wiring harness within the frame of the motorcycle.

The right side of the engine has a few more pieces that really start to bring the engine together. The oil pump and its gears, the gearshift shaft, the drive gear, and signal generator are all installed from the right side.

Gearshift shaft:

Oil pump and pump drive gears:

The primary drive gear, clutch sleeve hub, clutch plates, and pressure plate:

And finally the signal generator on the crankshaft:

Similar to the left side, the signal generator and clutch cover will go on once the engine is back in the frame.

The lower end of the engine is now operational. The crankshaft is connected to the drive gear and the transmission.

The parts bin is looking a lot better at this stage too:

More to do once the top end starts to come together, but I am thinking I will want to reinstall the engine to the frame before proceeding further. It is getting pretty heavy at this point.