1971 (nee 1974) Suzuki T500 first look & engine strip

[Olafskii]

Tearing into an old engine for the first time is always exiting.  But, it can also be stressful if the plan is to fix up, or restore the bike.  With parts prices for old 2-strokes now at usurious levels, and Canada Post levying a 20% 'fuel surcharge' (as in: "not Canada Post fault sir, but our fuel cost is up 20%".  Anyone who believes this I got a bridge for sale!) too many missing or damaged parts can push the project out of reach. 

This latest bike on the bench is the one I picked up in 100 Mile house in October of 2022.  The thinking was that this will be a parts bike for the 1975 T500 and the 1977 GT500.  (The '77 was to be a parts bike too as it was seized and covered in moss when I got it.  But, the moss cleaned up easily and the engine unseized after I left some diesel fuel sitting in it for a couple of weeks).  Now it's in the restoration queue!

This newest bike was advertised as a 1974 T500 as indicated by old Saskatchewan registration papers.  But, the steering head nameplate and serial numbers indicate that it's a 1971 model.  It was probably bought in 1971 but not registered for road use until 1974.  Then, some idiot bureaucrat at Sask Government insurance didn't remove his blinders and register it by the correct model year.   

The bike is painted white (one color it did not come in), is missing the right side cover, no side stand, and the center stand rolls over to a much larger than normal angle.  There is no ignition key and all the turn signals are missing, as are both handgrips.  However, both fenders are intact and in good condition, there is no crash damage on either muffler, the seat is original, (this is important--especially the metal trim which is unobtanium if a guy wants to make a period correct bike), it has an airbox that's in good shape, and a chainguard.  It has the correct 1971 gauges and the correct headlight shell--which is unique to the 1971.  Finally, the gas tank inside has never been 'lined', and there is very little rust.


As a first closer look, left side engine and points cover were taken off.  Several of the screws were missing but good news, nobody has tried to substitute SAE screws for the correct 6mm metric ones.  Part of the casing is broken away above the chain which is usually caused by when a chain breaks and piles up in the sprocket area.  The pre-insulated electrical connectors under the points cover are almost always a sign of electrical bodgery, and someone has used the airbox as a mixing surface for 2-pack epoxy.  Overall, not too bad.

 

[Olafskii]

The exhaust bolts came out easily.  This is always a stressful part of an initial disassembly.  The exhaust bolts can be seized and very difficult to remove.  If they break they usually need to be drilled which carries a whole lot of risk.  The left header pipe had a curious kink at the engine connection and a great big sloppy blob weld.  Maybe this was to fix a dent?  The good news is that Delkevic in the UK manufactures pattern replacement header pipes.


Three engine bolts and the engine lifted out.  T500 engines are heavy and I don't like to use my back as a lifting hoist.


The alternator rotor sits underneath the stator/points plate on a taper on the left side of the crankshaft.  An M16x1.25 bolt, threaded into the alternator and tightened with a rattle gun, releases the rotor from the taper.  But, where to get an M16x1.25 (fine thread) bolt?  Amazon or Ebay offered small quantities at usurious shipping costs. Northern Metallic saved my bacon.  They had one bolt in stock, 80mm long and the counterman apologetically said it's fully threaded.  $1.43.  Jackpot!


The rotor popped off easily and I did not loose the key! The left side crank seal shows no signs of leakage--a very good sign.

[Olafskii]

The cylinder barrels slid off quite easily so on this bike there was no need for the puller plate that I made for the '77 GT500. The clutch holding nut was mashed which was confusing given the overall excellent shape of all the other engine internals. I had to clean up the divots with my pencil grinder before I could get my 32mm socket onto the nut.  At first I thought that this damage might have somehow occurred at the factory.  But, based on some other damage I found, I've come around to thinking that the chain pile-up lead to this damage. 


The gears are all in excellent condition including the infamous 4th and 5th gears.  This, even though the gearbox did not have the 'mission oil plate' installed on the oil overflow weir* to the clutch chamber.  The shift forks are nice and straight, and within spec.  The cases sealant was the older style black stuff, and not the grey Three-Bond sealant that Suzuki used in later years.  My conclusion is that this engine has probably never been opened. 


However there was some curious damage that was not really obvious at first.  The left side clutch shaft dowel pin was mashed into the gearcase.  Normally this sort of damage occurs when some gorilla fails to line up the bearing locator hole with the dowel pin.  But I think this could also have happened with a traumatic chain pile-up in the chain case.  The clutch pushrod that passes through the clutch shaft looked like a pregnant banana.  It would have prevented the clutch from operating and was maybe what caused the bike to be parked. as seen below. 
 
 
The splines on the shift shaft were worn out but,  I managed to find a replacement.  The guy also had a side stand that he sold me. 
https://i.imgur.com/W8KkSxh.jpg

Olaf



*Oil Overflow Wier: This was a design flaw that Suzuki corrected starting in 1974.  With the earlier lower wier, the gearcase oil level runs too low to properly lubricate 4th and 5th gears.   Suzuki developed a fix that is described in service bulletin T-3 (May 1, 1975) in which a small piece of elastomeric material (known as the 'Mission Oil plate') increases the wier height.  Pattern versions of the Mission Oil Plate are still available from Claus Studios in California.