1975 T500 Engine out & strip

[Olafskii]

Got the 1975 T500 on the hoist. The idea is to get the crankshaft out and to Mongoose in Vancouver before spring.

The plan was to leave everything except the engine alone. But, the carbs were so badly seized that I could not pull up the slides to get the throttle cable out. I had to disconnect the throttle cable at the oil pump and handlebar and then pull the carbs out with the throttle cable. So I decided that before getting to the engine, I'd deal with the carbs.  I've never seen carbs so grungy on the inside. Most parts were so badly 'gummed' together that heat gun was needed to get stuff loose. (The ultrasonic cleaner got a good workout too). And, my lucky stars were shining when one of the pilot jets stripped inside the pilot tube. I was able to drill it and get it out with an 'easy out'. The carbs are now done and it's onto the engine

[Olafskii]

Engine on the bench. 6mm side cover screws were snug--every one of them needed the impact driver to loosen it.



Clutch basket looks good. But, someone has been in here before! Those nicks on the primary drive nut are not mine (I use the proper tools to flatten the lock washer) and I would not re-use an old lockwasher on the primary drive pinion. The gear teeth seem to be good; no spalling or pitting.




I took off the clutch and the right side stuff: points cover, points plate & stator and the alternator rotor.  The rotor came off without any problems. 
On balance the right side is in decent shape. The rotor still has lots of magnetism and there is no evidence of any water ingress or damage. The stator looks good although I haven't done any electrical checks yet. The 2-stroke oil sitting at the bottom of the casing on both sides suggests that the outer crank seals need to be replaced. For an engine of this vintage I'll send out the crank to get the center seals replaced too. The points cam was rusted and deeply pitted. This might have happened due to wet felt 'wipers' when the bike was parked. Since I plan to run points and condenser ignition, the points cam will be needed. I could try to polish out the pits but a lot of material would need to be removed. So, I've ordered an aftermarket replacement points cam from HVCCycle in Lincoln, Nebraska.

[Dennis]

Nice report. 
Peace & Grease, Dennis

[Olafskii]

Pulled the jugs off.  I use a puller plate when they’re tight or seized in place.  Only a dummkopf would use a prybar against those big lovely cooling fins.  In some places the crosshatching in the bores is still visible and there is no noticeable wear mark at the top.  The conrod bearings feel smooth and rod lateral endplay feels minimal.

The bores and pistons are all within spec so will be cleaned and re-used.  The piston ring endgaps are right of the ragged edge so rings will be replaced.  The crank was crated and is on it’s way down to Mongoose engine rebuilding in Port Coquitlam.

[Olafskii]

Oh dear!  Some putz has been here before!  This thrust washer goes on the other side of the right hand gear cluster bearing.  This error allows the first gear driven gear to ride right up against the gearbox casting.  It also prevents full engagement of the first gear shift dogs.  Fortunately there is no evidence of damage.  Elsewhere on the gear cluster this sort of error can sometimes cause two gears to engage at the same time.  But no damage is anywhere to be seen and all other thrust washers and spacers are where they should be.  Whew!

The gear cluster bearings are good.  The 4th & 5th gears (a weak point for these engines) have no spalling or flaking on the gear teeth and only some minor distress.  These gears will be removed and installed in the ’77 GT500  gearbox where the old 4th & 5th gears are truly knackered.
New 4th & 5th gears from Nova Racing will be installed in this gearbox.

[Dennis]

Why not put the new gears in the '77 and keep this one intact/original?

Dennis

[Olafskii]

The long term plan is to keep the '75 (and the '72) and to tastefully customize them. In my view these earlier T500's are better looking than the '76 and '77 GT500's.  Tasteful customization means no muffler tape and no loud 'crackle' pipes.  So the '75 and the '72 will get the best components that I have.

The still-good-but-2nd-choice components will go on the '77 which will eventually be sold to thin the herd.  Nova Racing gears are the best of the best so will stay in the bikes that I keep.