Featured Tiger 90 Rebuild

Two small chips on the teeth of the exhaust cam wheel (on the two teeth by the screwdriver blade). No visible cracks and no other chips, so I will use this.

 

The new plug for the sludge trap in the crank is in, just need to lock it with a punch.

 

Some of the barrel to crankcase studs came off with the barrel. Removing them now, there is just enough thread on the stud to lock two nuts on.

 

New oil seals in the gearbox case and primary drive side of the crankcase.

 

Parts, tools and materials laid out ready for reassembly. The sealant to go between the two crankcase halves is Loctite copper silicone which i’ve found gives the best results. You can tell it’s a special day as i’ve put clean newspaper down.

 

Ready to put things together, just remember to align the breather with the slot at the end of the inlet camshaft, and don’t forget the spring. Photos always make it appear as if there is loads of gasket sealant, it is only a smear, honest!

 

Back in the cradle, bolts and studs torqued down. Half time pinion in place.

 

Waiting for parts to arrive………. but at least the pinions in the timing chest are on and torqued down.

 

Replaced the sleeve bush in fourth gear. Before and after pics. Reamed to size inside.

 

Clutch springs are 1.7mm below specified size (50mm free length). Not surprising as they have been compressed for 40+ years. Not ideal, but i can live with it. The Triumph workshop manual says that up to 2.5mm reduction in length is acceptable.

 

inspection of the gear cluster is mostly good. The eight gears all have their teeth, no chips, but some wear and marks on the teeth. The dogs on the moving gears are slightly rounded off, but nothing exceptional. Mainshaft and layshaft are straight and splines are good. Layshaft bearing is good. Selector forks and selector channels in the gears are all good. Gear selector camplate is fine, and camstop and spring are both OK. Needle roller bearing at the end of the layshaft is good.
The less good bits are that the kickstart ratchet is a bit clunky, but i can’t see why, and the neutral pointer doesn’t show the full range, i’m guessing the hole in the vertical shaft for the gear indicator is elongated (the split pin is OK).

 

I’m going in…….

 

And we’re in. Before the strip down the gears all selected, and now, after the rebuild, they still do. I put some placeholder bolts in to keep the case flat and tight to the gasket.

 

Noticed an obvious bend in the holding plate for the kick start spring as i went to put it on. Maybe that’s something to do with the clunk when the kick start ratchet engages?

 

That’s where the oil seal in the primary cover has worn in to the bush. Eventually it will not be oil tight, added to which as the bush wears inside more oil will be escaping.

 

Dismantled the OPR valve, observing the warning not to clamp it in a vice. In spite of this the piston in it was locked solid. Turns out it was old oil residue that had set solid and even two months of soaking in oil hadn’t loosened it. Just need to clean it up, make sure it moves in and out freely then install it.

 

Oil pressure relief valve installed.

 

Front sprocket on the shaft. I had previously test fitted the sprocket when the gearbox was apart, as sometimes new sprockets need a bit of fettling and it’s easier to do that with the parts off the bike.