Featured 1964 Tiger 90 Restoration

The steel arrived today to make a swing arm spindle extractor. A length of 24mm internal diameter tubing, 20mm diameter bar some 30mm diameter bar, 12mm high tensile threaded rod and some M12 high tensile nuts. An M12 nut cannot be used to push the spindle through because it will not go through the swing arm bushes so I started by making a pusher from the 20mm bar. It needs to be around 180mm long but I can't bore a 12mm hole that long on my mini lathe so I decided to make it in 3 sections 60mm each. Progressively drilling the hole through the first section took a while because my smaller diameter drill bits only reach about 40mm so I had to go in from both ends. After drilling the hole I made a mandrel using the 12mm threaded rod and turned the outer diameter down to 19mm to pass through the bushes. I will make three more pusher pieces 40mm long which will be easier to make than the 60mm one.

 

The long impact screwdriver bit arrived today so I finally got the hidden screws out from the crank and split the crank cases. The sludge trap plug looked untouched and may never have been removed. I'm looking forward to seeing what horrors are inside except that I've mangled the plug a bit by using too small an impact bit... I've ordered a larger one so hopefully I can get it out eventually.
There is quite a lot of play in the timing side main. I measured the journal at 1.4308 in the big end direction and 1.4327 across. The spec is 1.4375/1.4380 so I'm 1.9 thou oval and 6.7 thou undersize! I don't have an internal micrometer so I'll either buy or make one and post the results...

 

I made an internal measuring tool from an M3 screw, two 6mm ball bearings and a couple of 3D printed parts (see photo). As I was measuring it I realised that I had been reading the micrometer wrongly and I confirmed this using my digital caliper. I was 5 thou out so I measured again. It's really hard to get consistent readings but these are the best I could get:

Journal:
1.4362 along the conrod line so 0.7 thou undersize.
1.4376 across so 0.1 thou within tolerance.
Giving 1.4 thou oval.

Bush
1.4404 so 1.4 thou oversize

So 2.8 thou worst case clearance. Double what it should be...

 

Spent the afternoon making a swing arm spindle puller on my mini lathe. It fitted great but despite applying considerable tension to the 12mm threaded rod and hitting it pretty hard on the end it will not budge. Maybe it needs heat or is rusted solid in the frame...

 

I've given up trying to remove the swing arm. There's absolutely no play in the bearings so I'll put some effort into getting grease into them.
Regarding the crank shaft. The big end bearings feel perfect so I'm sure will not require regrinding. The crank will fit between centres in my mini lathe so I'm planning to manually regrind it to remove the ovality. If all goes well the journal will be circular but 0.7thou undersize. I've ordered a bush that the vendor says measures 1.437 so if I get my crank to 1.436 I'll have 1 thou clearance. Fitting the bush into the crank case will close that up a bit so it could end up perfect...

 

The 12mm wide impact screwdriver bit arrived so I got the sludge trap plug out. The trap has certainly done it's job!

 

The contents of the sludge trap.
This engine had very little life left...

 

Really successful afternoon. Odane came round and cleaned the crank case halves while I dismantled the crank shaft. I showed him how to measure the big end bearing journals using the micrometer. Both big ends appear perfect and measure 1.4375" which is bang on the spec low limit. The lower shells show very little wear but the load bearing upper shells have started to break up. We used Plastigauge which showed 1.5 thou clearance.

 

We mounted the crank shaft in my mini lathe and used an oiled steel backed fine diamond chisel sharpening 'stone' held against the slowly rotating timing side journal with just finger pressure. There was a slightly raised ridge around a third of the diameter (the segment that carries the load), the other side was evenly worn. Gradually the ridge disappeared and the shine on the other side changed to a nice grey colour. After about half an hour the whole journal was a nice grey colour all the way round with no ridge. It measured between 1.4350 and 1.4355 which I feel is a great result. The new bush should be 1.4370 which gives a clearance of 1.5 to 2 thou which will be reduced when pressed into the crank case.

 

I threaded it M12 internally then made a slide hammer using M12 threaded rod. It came out easily. The plug needed the impact screwdriver almost all the way out so I may use it again. Good advice. Thanks.

 

"sometimes the crank will crack right through the punch mark"!!!
Thanks for the warning Speedy.

 

I've sent the barrels off to be rebored as there was a nasty ridge where the rings had rusted to the bore. The pistons are scored and were running a clearance of 20 thou! They will be bored to +40.
In the meantime Odane has sanded the rust off the rear mudguard and treated it with rust inhibitor and I've sprayed the underside with Halfords stone chip paint. It does not require undercoat and claims to be rust inhibiting. Although it goes on with an orange peel finish it dries smooth and deep matt black. You can paint over it so I will finish with silk black.

 

I've spent a lot of time pondering over the electrics, particularly the choice of electronic ignition. It's been pointed out to me that the original points are problematic although they worked fine for me. I settled on a system from Electrex World that includes a new rotor, stator, coil pack, CDI and voltage regulator. The ignition is independent of the battery and you can use an inexpensive (£15) capacitor instead of a battery. I have indicators so will use a battery. The ignition components are compact and all fit in the space under the tank where the old coils sat. I designed and printed a block to mount them to the frame.

 

The missus was out all day so I took the opportunity to heat the crank case halves in her posh Neff oven and drive out the bearings. I put each crank case half in a large turkey basting bag to hopefully contain any unpleasant odours. She's home now and doesn't seem to have noticed...
The old bearings are really worn so they need replacing.
I cleaned the cases and scraped off old gasket bits then got the new bearings out of their packaging ready to go in. I bought SKF branded ball bearings and assumed I'd get quality Swedish products. Checking them before pressing them in I discovered that the gearbox final drive bearing, made in Poland, is super smooth with no play but the crank shaft ball bearing made in Bulgaria and branded "SKF Explorer" feels loose and rattles when shaken. Needless to say I didn't fit them pending advice from you guys. What do you think? Is it ok that the crank shaft main bearing feels loose? Is it meant to be like this?

 

So, I've done some research and found that the bearing is a c3 type which means it has 0.033mm clearance. This will close up a bit when installed because the inner ring expands and the outer ring contracts. Clearance is also necessary for high speed running and to accommodate thermal expansion.
So the bearing is good and will get fitted the next time the missus goes out for the day.

 

Spent the last few days cleaning and spraying parts. The Toolstation industrial satin black paint I'm using sprays nicely and dries quickly even in this cold weather.
Today I replaced the crank shaft sludge trap using the new hex plug. It is not as tight as the original slotted one. I had bought fresh Loctite from eBay but when I opened the packet found it is a Chinese copy. I'll use it on mudguard bolts but not in my engine, so a trip to Halfords who had only Loctite 248. It comes in a Pritt Stick tube and will presumably keep the plug in place.
Spent some time cleaning the rear brake shoes but decided to order new ones because there's only about 1mm left before the rivets and they are not that expensive.