The first issue was the clutch side cover on the 1976 engine as I could not get the shift lever off. I had looked at it very briefly months ago and had just been giving it a shot of penetrating oil whenever I walked past it in the shop. Now that I had it up on the bench, I finally took a close look at it, and soon realised that the reason it wouldn't come loose was that the shifter arm had been welded to the shifter shaft !!! I have to admit, I hadn't seen that particular bodge before, and it didn't bode well for the condition of the rest of the engine. After a few minutes of grinding, it was sorted and I was able to get the shifter off and then the left side cover. The chain had obviously come loose at some point as there was the typical damage to the case and neutral indicator housing. After that, it was time to pull the heads off and take a look at how bad the barrels and pistons were. Thankfully, the 1976 engine actually seemed to be in pretty good shape internally - the barrels were still on their original bore and there were no obvious signs of oil starvation, the crankshaft felt good and there were no signs of excessive play in the con-rods and small and big ends. There was no sign of gear pitting in the transmission, and the clutch and clutch plates all looked almost new. The 1977 engine was a different story entirely. |
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| When I pulled the heads on the 1977 engine. I was quite surprised to
find that one barrel was at second over, and the other was still on
standard bore ! As well, there were obvious signs of fairly serious
engine damage in the past as the left cylinder head had a deep gouge in
it - and then most surprising of all, the right cylinder
head is actually cracked the width of the cylinder right through the
spark plug hole, so both heads are pretty much scrap. The barrels also have been played with - the intakes have both been opened up, probably to try and make the engine breathe a bit better which in itself is not a bad thing, but the liner on the left cylinder that had been bored to second over is cracked in the area of the intake transfer ports - so that is scrap also. The crankshaft seems OK as well as the con-rods and the small and big ends, but the engine must have been really unbalanced with having the cylinder bores unmatched and probably buzzed like crazy at speed. It also will have stressed the crankshaft bearings so they will need to be looked at carefully. |
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| The
other problem I found, was that whoever rebuilt the engine last time
hadn't remembered to bend up the locking tab on the clutch boss nut,
and so at some point the clutch basket had come loose and had 'reshaped' the
inside of the right side engine cover. As a result, both of those were not
much use either, and several of the cork plates were chewed and the metal friction plates were blued. Thankfully the gear clusters were in good shape and it at least shifted freely. |
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The
good news out of this is that I did have one set of barrels and
heads which seemed OK from the 1976 engine together with the clutch
and engine side covers, so I can get get at least one complete engine
from the two. I also have four con-rods which seem to be in good
shape which is very nice as these specific ones have not been available
anywhere as NOS for years. As of this writing, they are being re-produced in small numbers in the UK by Pete O'Dell.
The crankshaft bearings likewise pretty much are not available from
Suzuki - you can have them made at considerable cost, and they also are
being reproduced by Pete O'Dell and a few others, but it was very nice
to find that, at first glance at least, the original crankshaft
bearings look to be salvageable.
I also have two complete sets of gear clusters, and as the transmission
was same from 1968 through till 1977 that may be useful on a future
project I'm considering, so of the two engines I've started with, I
will not have very much left over by the time I put one good one
together !
| Owners of Suzuki twins with oil injection from this era often report
air leaks in the oil injector lines. Unlike the triples, the twins use
a split feed line between the pump and the point of injection, and it
seems that after 35+ years. what ever Suzuki used to glue these
together is starting to fail, or possibly it is just hair-line cracks
developing. Whatever the case, I am putting a drop or two of epoxy on
the joint areas (marked in the photo to the right), and will also be
flushing out the lines with methyl hydrate to make sure the check
valves at the end of each line are also working properly. I've included a photo to the far right. The same check
valve design is used on the Suzuki triples and care must be taken to
not damage the seat or small spring so blowing these out with
compressed air is a recipe for disaster as new ones haven't been
available from Suzuki for quite some time. Update: the epoxy didn't work as well as I'd hoped, and I did have trouble with air leaks in the injector lines at the splitter so I ended up sourcing NOS lines from Marcel in The Netherlands. Fast service, and recommended ! I will try again to re-glue the fittings at some point, but for now what I have is working. |
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| Continuing on with the oil pump - the two that I had were in poor shape
and so I needed to be dis-assembled and replace the oil seals, and of
course these were not offered by Suzuki as the pumps themselves were
never intended to be repaired. It took a bit of sleuthing to figure out
what will actually fit and where to buy them. This is a
single piston style pump, and while a lot simpler than the one used on
the Suzuki triples it is also pretty robust and the
seals are all easily replaceable if you can find the correct sizes. The photo to the left shows the disassembled pump and a larger copy of the image is available by clicking here. I had trouble locating 1/2 mm sizes locally, but after a bit of searching found a place in the USA called MFGSupply that had stock and also had stock at reasonable prices. NOTE: the one fitting that is a left hand thread !!!!! With the pump all back together and installed, it is working great with no leaks so I'm happy. |
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| The coils on the magneto
and timing plate were damaged with bare spots in the insulation on the
wires, and also coming apart as the cardboard spacers had turned to
powder and were long gone leaving the coils to flop back and forth on
the armatures. Luckily new coils are still available from Suzuki in the
USA (not in Canada) so I was able to buy a full replacement set. I
could have just rewound the coils as of course the armatures themselves
are steel - rather than fiddle with it, I just bought the new ones and
justified the cost to myself on the basis that it would be one less
thing to be worrying about later. On the T/GT500′s and of course many other bikes also, the magneto coils and in this case also the pickup.trigger coils used for the electronic ignition, are soldered in, and given it had been quite a few years since I had wielded a soldering gun in anger, I took my time. The photo to the right shows the completed job with the new sleeving installed. |
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| At some point during its
long sleep, the bike had obviously been left laying for a while on its
left side, as the left carburettor was literally full of dried dirt. It
took me ages to get the fuel inlet and the other small passageways and
jets cleaned out using repeated soaks in my ultrasonic cleaner,
followed by solvent washes and air blowing. One of the floats wouldn't
- float that is - and so had to be replaced, and a part in the throttle
slide was missing so while I was waiting for a new one to arrive I made
one from some scrap aluminium. The air inlet and outlet boots are new,
and of course so are the o-rings, gaskets and seals. After many hours
of fiddling and adjusting though I was ready to try them on the engine
- while it did start, and even ran 'OK' they clearly still weren't
right so I spent another whole day cleaning them yet again and at the
end of that, at last had some success ! I do still plan to replace one needle as it is slightly pitted, the engine now pulls cleanly through the rev range so any additional changes can wait till after the engine is well broken in. |  |
