Topic: TRIBSA

[martin99]

Meet my new mistress, who I expect to spend many a long winters' evening with and upon whom I will no doubt lavish bucket loads of my hard-earned cash. She will become the focus of resentment for my long-suffering wife, who I guarantee will threaten to kick her in the headlight before this sordid tale reaches it's conclusion. Yep, been there before



This bike started life as a BSA A7 Shooting Star in 1959. I've got the original logbook (title?) that shows it was fitted with a Triumph T110 650cc engine in or around 1965, and was mated to it's current engine, a 1953 Triumph Tiger T100 500cc, in 1973.

I first knew of this bike about four years ago, when a mate picked it up for peanuts when he did a deal on a Matchless - literally a 'Well as you're here do you want to make me an offer for that old bike in the back of my van?' scenario. Turns out it had been 'in the back of the van' for twelve or so years.

Since bringing it home, my mate has teased me with photos of it from time to time and I have hassled him to part with it, which he always said he would never do. A few months ago I get a call from him - his girlfriend has fcked off, left him in debt and he needs cash quickly. Obviously wishing to be as supportive to my crest-fallen mate as possible, and keen to exploit the situation at the same time, I made him a cheeky offer and he took it.

I've had to keep it under a cover until now, but now I have sold the Yamaha Srx600 (aka money-pit-devil-bike-from-Hell) I've finally been able to get it on the lift to start work on it.

In this pic, you will see that I have asked my wife to remove herself from the sun-bed as I did not want her presence to detract from the good looks and beautiful lines of my motorbike.









This bike may be 57yrs old, but it was clearly way ahead of it's time - check out that adjustable steering damper!

Anyways, I thought it would be nice to record progress on here, for posterity and giggles, I know there's a lot of closet Brit bike lovers out there so please do chip in if you see me about to screw anything up!

[ekpent]

 No closet Brit bike lover here but it looks like it was not neglected too bad in the past and cool that you have such a solid history.  What is its most needful treatment before its roadworthy ?

[martin99]

No closet Brit bike lover here but it looks like it was not neglected too bad in the past and cool that you have such a solid history.  What is its most needful treatment before its roadworthy ?

Plan is upside-down forks, clip-ons, mag wheels, mono-shock conversion and brat-style seat.



Only Joking

Apart from the obvious deviation from original, and those mile-wide handlebars, it's pretty much as when it left the factory, as far as I can make out. As for its most needful treatment, I don't really know until I get stuck in. It does run, quite well in fact, and the gears select ok.

I really, really love this bike, both for it's looks and simplicity. To start it it's just a case of fuel tap on, tickle the carb and kick. To stop,a hand over the velocity stack is all that's needed.

I could go all out and do a full resto, but apart from being super-expensive I really like the fact that it shows it's age, pitted chrome n'all, so cosmetically all it's going to get is the oily rag treatment.

I do like to know my bikes are mechanically sound and roadworthy though, so the engine will be stripped and checked and refreshed as necessary, as will the running gear - wheels, brakes, bearings, suspension etc. A rewire is also on the cards, probably a 12v conversion, with a proper ignition switch with keys to give it a fighting chance of remaining wherever I leave it!

[Stev-o]

Congrats.  Closet Brit bike lover here, don't tell anyone!

[Powderman]

Nice score. Good year 1953, my birth year.

[Thekramer666]

Yes beautiful congrats

[martin99]

Thanks fellas.

Managed to get some time on it yesterday. I wasn't sure if I would have enough frame clearance to remove the lump as a unit - after all, that engine was never meant to be in there - so I removed the rocker boxes first, then carb, then head. Things are tight in there - there wasn't enough room between the carb and frame tube to draw out the slide, I had to unbolt the carb and pull it down. Just hope I remember when I'm putting it back together!:

Pistons look surprisingly clean - this is after a quick wipe with a cloth-


They have '63 5' stamped on them. I know 63mm is standard bore, so assuming the '5' stands for .5mm, these are half a millimeter oversize, or .020", which is maximum bore for the sleeves. Like I say, just guessing at this point, I need to research some more.

The head shows similar light use - no heavy carbon build-up, obviously been running very rich but I have had it ticking over on various occasions and not took it out for a decent run.


So at this point I'm optimistic. The top-end looks like it's been refreshed already, and not too many miles put on it subsequently. The tax disc shows it was last on the road in 2002, so the 'twelve years in a van' doesn't quite add up - maybe ten. I checked with my mate - he changed the plugs, but other than that he did nothing to the engine while he had it, just started it every now and then. I don't want to ask him anything else about it if I can help it, he's still a bit sore - no bird, no bike ha ha

[simon#42]

martin what was up with the srx600 ?  i have always quite liked the idea of one

[martin99]

martin what was up with the srx600 ?  i have always quite liked the idea of one

Yes Simon, so did I. I was chuffed to nuts when I picked it up. This one always seemed a little bit special, because I bought it from the late Dave Newitt of XT500 fame. He said he had intended to restore it himself, however I heard he passed away shortly after so my guess is he knew what was coming and was putting his house in order. Sad really.

Anyway, I completely rebuilt it, sinking a lot of cash into it - Yamaha prices are bloody ridiculous (inlet rubbers £75 each?). Once the decompression cable was set correctly, I had it ticking over quite nicely, but it always ran lean - the headers (stainless Predator) used to glow red hot, even with a fan cooling them. I messed about with it, got it a little better, lost interest and put it away for a couple of weeks while I went on holiday. When I came home, it refused to start. I tried every combination under the sun to get it going, no joy whatsoever. Meanwhile I was eager to get on with the beezer, so I cut my losses and sold the Srx as a non-runner. Shame really, I'm sure someone who knows them could have sorted it.

[martin99]

Did I say I was optimistic? Well you know what they say about optimism, it doesn't last long (although I might have just made that up!).

First job today was to drain the oil.


The hole in the gauze is meant to be there, it's for the pick-up pipe. The other stuff shouldn't be though

Has the oil been in there so long it's crystalised? Or is it evidence of a previous catastrophe?
This is the biggest bit.


Looks like a chunk of conrod to me Thank goodness I decided to tear the engine down, rather than leave as was.

Off with the primary cover so I can detach the engine from the gearbox.


I expected to see a four-spring clutch in there, according to all the manuals I'm working from. The later T110 and T120s used a three spring, so perhaps this one has been carried over from the 650 that was fitted prior to the present motor. That chain by the way is as tight as tight can be - should have at least a half inch of slack. I'm now beginning to think that this motor hasn't been quite as lovingly cared for as I originally thought

The clutch stack seems to be light of a few plates too - the inside of the outer cover suggests an explanation -


Anyway, not a bad day's work seeing as I had a list of umpteen other (apparently more important) things to do that her indoors had left me.


 

[simon#42]

sorry to hear about the yamaha martin , the tribsa is looking good though

[martin99]

Don't let my story deter you Simon, I still think they're great looking bikes. I just lost heart with mine.

[martin99]

So, cracking on, I've made a rudimentery engine stand out of a few offcuts and a wall-tie to keep it all steady while I'm working on it



Other essential workshop items are tea, beer and smokes.

Elastic bands around the tappets to stop 'em going astray...


And after copious amounts of heat and WD40 and a few careful taps with a rubber mallet, the barrells are separated to reveal.....this


So that's where that chunk of ally came from. Not a conrod, but one of the 'ears' on one of the tappet blocks. Probably due to some ham-fisted fcker not taking enough care on assembly

[martin99]

And here's what can happen if you don't take proper care...





So that's one shagged piston then.
The bore has actually done a little better...



Signs of heat in there, and light scoring where the pieces of tappet block got jammed up. The picture makes it look a lot worse than it is, and I actually think this can be salvaged with a light hone. I'll need to measure everything up properly first of course.

Such a shame . The inside of the crankcase looks spotless, the rods look new - there's no dings or scatches. There is no discernible play in the big-ends. The pistons have no carbon build-up inside or out. They are GPM make (Italian I think?) so clearly replaced in recent times. Looks like he fell at the last hurdle.



I'm going to have to split those cases even though I suspect the crank has probably been rebuilt, just can't be certain there's not any more shrapnel hiding in there waiting to screw up the other piston!
 

[70CB750]

Following, good luck!

[martin99]

Following, good luck!

Thanks Prokop. I've got a feeling there are more horror stories yet to be uncovered

[Stev-o]

Sorry to see.  Looks like the Brit motor rejected the Italian Pistons. 

[Powderman]

Bummer

[grcamna2]

Nice BSA 

[martin99]

The timing cover came off without any dramas, although I dound that the Allen bolt top right was spinning in it's hole, so I suspected a stripped thread.



Incidentally, Triumph didn't use a timing cover gasket on these motors.

Here's the damaged thread



A bit more than a stripped thread right? I'm thinking Mr Hamfist has left his mark here too. I can imagine his thought process - 'hmmm, how do I stop the shafts turning while I do those nuts up? I know, I'll wedge a screwdriver in here'.

Same train of thought probably responsible for the broken tooth on the intermediate gear...



People who don't take proper care and attention when working on museum-piece motorbike engines piss me off. It's not even like it's complicated.

[martin99]

More progress this evening

Removed the magneto and crank pinion. The manual calls for a special (and expensive) tool to remove the pinion, but with some very careful prying I managed to get it off. It's not on a taper, so the only thing that would make it tight is crud. I'm pretty convinced now that this has been opened up before, so it hasn't had time (or enough use) to be a problem.

The removal of the camwheels also calls for a special tool, but the cases can be separated without removing them. I found that once the drive side cover was removed, I was able to drift out the camshafts with a brass drift, at the same time liberating the camwheels without damaging them.

The inlet cam holds the breather mechanism, which should include a spring. The spring is not there. I am not surprised.

This is just before I removed the cases from my stand to split them..



Drive side parted easily. The timing side however is proving difficult. The crank is stuck solid in the inner race of the bearing. I've tried and tried to shift it, but it won't budge . I've hit it, heated it, WD40'd it, run lots of cycles and combinations of all such methods, and still it doesn't want to know. I'm afraid to whack it any harder for fear of damaging the case. I had been trying to tap it out, in the hope that the bearing had been replaced already. But now I'm resigning myself to having to destroy it.

It's currently raised up on blocks with about an inch gap between the crank and the bench, so when it does give it won't have far to go.





Any ideas? I'm thinking it's time to grind down the inner race so it can fall through the rollers, but if anyone's got a better idea I'd love to hear it.

This is the project that just keeps on giving!

[simon#42]

hi martin , if you can get enough heat into the case the bearing should come out with the crank , then you can attack it properly !

[martin99]

If only I could Simon. The bearing is retained by a circlip inside the case, hence I don't want to hammer the crap out of it.

[grcamna2]

If only I could Simon. The bearing is retained by a circlip inside the case, hence I don't want to hammer the crap out of it.

Possibly put it into the freezer for a while and then remove and heat the outer case ?

[martin99]

If only I could Simon. The bearing is retained by a circlip inside the case, hence I don't want to hammer the crap out of it.

Possibly put it into the freezer for a while and then remove and heat the outer case ?

As I have been using heat the bearing has come loose in it's housing several times, so I don't envisage any problems taking it out of the case. It doesn't fall out because it is held on the inside by a circlip running in a groove machined in the housing - in other words, when the case is heated and the bearing is loose the whole assembly (bearing and crank) is being held by the circlip. If I hit it too hard I could easily break something.

The problem is that the crank is jammed tight in the inner race. Once I get the crank free I'll be able to remove the circlip in the bearing housing and remove the bearing.

I'm going to try a few more heat cycles this evening. It's been soaking in penetrating oil all day. But if that doesn't shift it, I'll be breaking out the Dremel on the lip of the inner race tomorrow.