Featured Tiger 90 Rebuild

Doh! It’s not a dowel hole, it’s where the wires for the points exit the case. :-/

 

Pistons off. The rings are gummed solid. Now the pistons are out of the barrel and the bores can be inspected. It looks like the pistons were stuck to the bores with carbon and old oil, not rust as I had speculated. The rust visible in the bores is very light and scrubs off. If the pistons clean up all right and the clearances are within spec, then I may get away with just new rings with a honing, and not need a rebore. There are lots of “ifs” there, maybe I’m being too optimistic?

 

Gear wheel on the exhaust camshaft was a tight fit, but came off without any drama.

 

Just the nut and gear on the end of the crankshaft to remove now.

 

Crank end nut and gear removed. I will inspect the camshaft bushes when the cases have been split and I take the camshafts out then. This way I can leave the camshaft retaining plates in situ.

 

Gear cluster came out this morning.

 

Taking out the studs and nuts that hold the crank cases together. Don’t forget the two screws in the mouth.

 

Then crack open the two halves like an Easter egg.

 

OPR valve, with some dirt in the gauze.

 

I assumed that when the crankcase was split the camshafts could be taken out from the inside, meaning I wouldn’t have to remove the retaining plates in the timing chest. It looks like I’m wrong as they won’t come out.

 

Bath time!

 

Both cases mostly clean. Mating faces checked true, and free of bumps or burrs. Threads chased, bearings and bushes are all in good condition with clearances within spec. Stud holes cleaned through.
Next job is to check oilways are clear.

 

Plug for sludge trap came out with a bit of friendly persuasion. Sludge trap not too full, which is good.

 

Sludge trap now fully out. The workshop manual says use a bent spoke to pull it out. Ha! That went nowhere, but a 5/8 tap cut a thread inside it and then a 5/8 nut tightened down pulled it out.

 

That’s an elegant engineering solution @darkman I was happy to get it out without damaging it.

 

The crankshaft galleries are now clean. The journals on the big ends and the end of the crank are in very good shape and just needed a very light polish. (The big end shells and crankcase main bush are correspondingly good.) Reassembly of the crank can now begin.