1971 Triumph Bonneville Restoration: Gudgeons, Johnson Rods & Cylinders out! (oh my)

I've got a degree in English, but working on the old Bonneville is stressing out even my vocabulary:

That'd be your gudgeon pin right there.

Gudgeon: one who will bite at any bait or swallow anything, credulous or gullible person Mer. V. I. i. 102.  (that might apply to this project)

Definition of gudgeon

1: PIVOT sense 1, JOURNAL  (we're getting closer)

2: a socket for a rudder pintle (a rudder pintle?)

Definition of gudgeon pin: WRIST PIN

Definition of wrist pin: a stud or pin that forms a journal (as in a crosshead) for a connecting rod (that's it!)

They can make up anything! Nobody knows!  Well, you need a new Johnson Rod in here!

A few people know, George.  Consumer ignorance is expensive, but who has time

to understand the machines they depend on?

Gudgeon pins?  After the massive fight that was removing the seized cylinder head, I was bracing for misery, but I was able to pop the circlips (!) out and tap the gudgeon pins (!) through with no sweating and swearing.  Pink Floyd was playing on the computer and I think music from its era calms the old Bonneville down when I'm working on it.

The circlips popped out easily and a 3/8 inch socket extension was the perfect size to tap out the 'wrist' pins.  I thought the one on the seized side might cause more problems because it had been stuck in place with moisture but it didn't and both came out easily leaving a motor bereft of its pistons.

British Cycle Supply Co. delivered my 750cc kit quickly and without any headaches (and also for about $200 less than comparable kits out of the USA), so I got the shiny new bits out and had a look:

You'd think a 750cc head would look significantly different to the stock 650cc unit, but you have to look closely to see a difference in size.

I had a close look at the connecting rods and they appear to be in good shape and the bottom end of the motor moves freely.  I think next steps are to remove the rest of the engine from the frame, give the oil-in-frame a deep clean and then recoat it with some quality paint.  With the frame cleaned up and sorted I'll strip the rest of the motor and clean everything out to ensure nothing's whacky before I begin the great rebuild.

I could just chuck it all back together now and hope for the best, but if it ends up having other niggles rushing things at this point is just false economy.  I'm not worried about making the bike look mint, but I do want it to be dependable and that wouldn't be the case if I haven't checked it over completely after such a long (30 year?) layoff.  An engine out deep restoration was always the intention here and I'm not in any kind of rush since the other two bikes are both five by five and felt fantastic on their first rides of the year this past weekend.

The gudgeon pin itself looks to be in good shape, which is good because the head kit didn't come with new ones.  The circlips came out nicely too but the kit did come with those.  It amazes me that even specialized material like that in these cylinders can withstand the extreme forces they operate in.  This Bonnie had done at least twenty thousand miles on these cylinders and they're still in remarkable shape considering they were face to face with more than 17 controlled explosions every second (a spark plug typically fires about 17 times per second at 2000rpm!).  You'd think all that heat and violence would cause more wear than I'm seeing in the beating heart of this motor.

This is the 3/8 inch socket extension I used to tap the gudgeon pins out.  Nothing grabbed or slowed the process down and I barely had to apply any pressure.  I might have even been able to push them out had I been so inclined.  I caught the pin as it came loose and the cylinder lifted off the connecting rods easily.  Again, considering the extreme conditions the heart of every engine operates under, I'm impressed by the engineering and metallurgy that makes all this possible.

The new cylinders don't have the carbon build up from all those combustion cycles and look pretty spectacular in their pristine newness:

Here's the whole kit from British Cycle Supply.  It includes the cylinder head, cylinders, piston rings, circlips for the gudgeon pins and a head gasket.  I swiped the last one they had in stock for $688.75CAD ($535USD - told you I got a good deal).  Unfortunately I might be the last person on the planet to get a 750cc kit that cheap.  Prices will be going up on the new stock and probably even higher than that as we're in an inflationary spiral thanks to Putin overreaching and years of pandemic fueled broken supply chains; we live in interesting times.

Another tool came in that's interesting.  I was reading Practical Sportsbikes last week (highly recommended if you love bikes and getting your hands dirty on them), and editor Chris mentioned an endoscope smartphone camera he was using on a project bike to inspect the internal parts of an engine.  I found one on Amazon for under $40CAD and it came in on the weekend.  It lets you see parts of the engine that haven't seen light before.  It's an exciting thing that offers you a look into the secret life of engines.  I'm looking forward to using it as i continue to work on the Bonnie.

Through an inspection hole inside the engine - it's disco in there!

That look on my face after the first ride in a long, long time.

The 12 year old Kawasaki (left) and the 19 year old (!) Tiger (right) were keen to turn a wheel after a long hibernation.

Bison were out bisoning at Black Power Bison Co. when I was out for a ride in balmy 6°C March Sunday.

650cc Air Cooled Triumph Bonneville Exhaust and Seat Options

More 1971 Triumph Bonneville restoration project research (all prices courtesy of BritCycle):

High pipes:

721-T74X exhaust pipes - $304.51/pair.
711-709669/9670 mufflers - $486.00/pair.
2x 742-158 clamps - $16.61 ea.
70-9673 “H” connector - $72.28.
2x 742-112 clamps - $16.61 ea.

TOTAL:  $930

Plus associated bracketry and hardware, etc if needed. The one item we’ll have difficulty sourcing will be the ‘chip basket’ heatshield; our manufacturer of those long since retired.

Looking like Steve McQueen on a scrambler styled Bonneville costs extra!  Britcycle said they might have some scratched and dented options on sale, but those aren't regular stock (obviously).

Stock(ish) exhaust system:

721-T79 exhaust pipes - $289.02/pair.

712-102 Dunstall decibel replica mufflers - $330.32/pair.
70-9888 balance tube - $29.09.
2x 742-138 clamps - $16.61 ea.

TOTAL:  $683

What I'd really like to do is form my own pipes, but I don't have the space, equipment or time to do that.  For this project I think I'll use it as a learning process and get this particular Bonneville cleaned up and mechanically sorted and leave the radical customizations to a future time when I'm loaded, have lots of free time and a much bigger workshop with a full range of tooling in it.

I think stock is the way I'll go on exhausts...

As far as seats go, BritCycle has just the sort of thing I'm looking for: 

  

Custom Seat, 71on T120, Clip Type

Part Number 513-05

The only thing that might knock it out of contention is if, price and fit-wise, Corbin's customizable seat is in the ballpark.  It says they might fit a '71 but they're mainly for '72 Triumph twins and up.

Quality (made in England) newly manufactured seats specific to the oil in frame 650 twins run at about $500US ($612CAD) - I'm not sure what Britcycle's go for.  The customizable (and probably higher quality) Corbin is $618US ($788CAD).  There are cheaper options manufactured in India & China to less exacting standards to consider too.  I'll be keeping that all in mind as I juggle seat options and make a decision.

Old Bikes Tell A Story

I took the big SLR into the shop for some closeups.  These are photos from the 1971 Triumph Bonneville T120 project currently in process.

Call it patina, or scars, but the years on an old bike tell a story...

The 'spare' cylinder sleeves after some clean up.

Orange was the colour of panic in the early 80s.  The cylinder head was covered in this stuff in an attempt to seal a leaky motor during the aborted chopper phase of this bike's life.

That's the motor stamping (from Jan-Feb 1971).

Lucas! The Prince of Darkness™

My kind of still life.

Patina that tells a tale.

1971 OiF Triumph Bonneville Restoration: a seized top end

The old Triumph motor has refused to turn ever since I picked it up in the fall.  Every attempt at cycling the engine has failed so last weekend I dug into the top end, which turned out to be much more difficult than it needed to be.

Many moons ago I was putting myself through university by working as the service manager at an automotive shop.  One of our technicians, Jeff, always cheerfully described a situation where you're up against parts that don't want to move as a 'bend the fuck out of it' situation.  I'm no fan of pointless violence when it comes to mechanics, but there does come a point where you've either got to 'give 'er' (another of his favourite sayings) or give up.

Your mood when performing mechanical taks seeps into the machine.  If you're angry when you do repairs, that anger ends up in the mechanical work you're doing, which usually doesn't end well.  A Zen approach to mechanics usually creates a zen machine that doesn't emit the drama that an angry machine will.  Having said all of that, I'd pretty much emptied my swearing vocab by the time I had untangled this Triumph twin on Sunday.

Having never worked on this kind of motor before, I was lucky enough to get a spare head and cylinder sleeve when I got the bike, so rather than go in blind I disassembled the spare unit first to see how it all went together.

I continue to enjoy working on this pre-digital, very mechanical motorbike.  While it isn't as efficient and exact as a modern bike, there is something very satisfying about getting the mechanical bits lined up so that they work together.  When it's finally running it'll feel like I've rebuilt a Swiss watch.

With the practice head disassembled, I began removing the head on the bike.  It came apart as my reconnaissance suggested it would and looked mechanically sound with no discolouration or obvious wear.  The bad news came as I finally got down to the head gasket.

The right hand cylinder looked fantastic, but the left side was a mess with a thick layer of corrosion and an obviously seized-in-the-sleeve cylinder.  I'd expect to see something like this on a water cooled engine when the head gasket has failed allowing water and coolant into the cylinder, but this is an air cooled unit with no coolant in sight.  My best guess is someone left the spark plug out in a damp environment for an extended period of time letting moisture in to disastrous effect.  It's amazing what a bit of laziness or stupidity can be amplified into over time.

With a cylinder seized in the sleeve, I was left in a bind (see what I did there?).  I left it soaking in brake fluid overnight (I'd tried WD40 previously), but the next day it was just as stuck.  I applied heat, and then tried to lever the head off the cylinder to no effect, which led to that Jeff moment where I had to decide how far I'm willing to go to win (the answer is: all the way, in case you were wondering).

What followed was longer and longer breaker bars to apply more leverage, mixed with some applied heat from the propane torch.  What finally ended up working after a couple of hours of swearing and sweat was applying heat, inserting a long piece of wood to lever the head up while applying some focused violence to the cylinder top.  Millimetre by millimetre the cylinder sleeve eased up until the head finally came free, which was good because I was all out of swear words by that point.

I was rewarded with a couple of nice observations once the damned thing came off.  Firstly, the bottom end moved very smoothly for a motor that hasn't spun in 30 years.  There is no play or noise in the big end as it turns.  Secondly, the kickstarter I rebuilt the other week works perfectly, engaging and spinning the motor when applied and not interfering when left, which was satisfying.

Looking at the jammed cylinder, it looks heat seized with burn marks all over the inside and physical damage up the side.  If replacements aren't crazy, I might use the spare head I've got to get things into motion, but if it's going to cost a lot to the replace these bits I think I'm looking at a more aggressive customization option:  a 750cc big-bore kit.

Dropping $1000 into a broken motor seems extreme (it is extreme), but I've had to recalibrate my what-I'm-willing-to-pay index throughout this project; vintage ain't cheap.  If it's going to cost the better part of $500 to get the motor back to stock, why not get all new parts and get an engine upgrade in the process?

Before: sleeves like that usually slide off.  Cylinders are snug but not stuck.

After: a couple of sweaty, intense hours later.  It was a satisfying win.

I've done a number of projects now where I get a sidelined bike back on the road, the most recent of which was a '97 Honda Fireblade, but I've never had to do a complete engine rebuild.  Unlike some of my more fraught earlier mechanical work on the only bike I owned that was keeping me from the far-too-short Canadian riding season, I can take my time with the Bonnie and go all the way if it needs it and I'm up for it.  The only thing producing drag is my inherent cheapness.

I'm still intent on making sure the project pays for itself.  It doesn't have to pay me for my time, this is a hobby, but when I sell a restored machine and it balances the books in terms of purchase price and parts, I find that inherently satisfying; it means my hobby is a zero-sum game.  The Bonnie currently owes me $1500 for the bike and spares and another $500 in parts so far.  Rebuilt in running shape (but customized and I'd say pretty fugly) similar Bonnies are asking $7500.  If I can mechanically restore this bike to good running order and clean it up, a $5000 budget should see me well into the black.

Now to decide how to drop the next three grand on this thing...

Some other photos from the work this past weekend:

Seized cylinder soaking in brake fluid overnight.

First look at the head gasket after getting the cylinder sleeve off.

A disappointing first look into the heart of the Triumph.

This is the head on the bike motor.  The other head must be from an earlier machine, or it's missing parts.  Those risers with bolt holes in the top were on the '71 top end but not on the other one, which looks to be an earlier unit (Triumph built the 650 twin for many years).

I get a great deal of satisfaction from cleaning up the old parts on the wheel in the shop.  This is an exhaust clamp, lovely patina!

This is the 'practice' top end on the bench.  Unlike other top ends I've been in (my 'modern' Triumph Tiger, the Fireblade, etc), this isn't an overhead cam motor.  It uses push rods to operate the valves from down below (they're dead centre in the photo).

How Bespoke is Too Bespoke?

Owning a Fireblade checked a box, taught me
many things and was a zero cost experience!

I always try to balance out bike projects so that I land in the black on them.  I've gotten pretty good at this.  The Fireblade Project cost me about $2300 all in and then I got to ride it for a season before selling it for $2500, which I then put towards the Concours14.  Even with fancy seats, windshields and other gubbins, the Connie only owes me about $7000.  Older model, double the mileage bikes are going for eight grand, so I'm still ahead there too.

People who throw big money down on customization that they like seem to think other people will pay extra to adopt their choices and tastes, which never made a lot of sense to me.  This goes for houses or in vehicles - just because you're willing to pay a premium to get a certain look, doesn't mean anyone else is, and expecting them to shell out for your choices is a bit naive.

The Concours was a cagey purchase that
still has me well in the black.

What does always sell is functionality.  As much as I'd like to get all romantic and throw money at the old Triumph I'm restoring, I'm more interested in making it work, and then riding it.  To that end, I'm not interested in creating a perfect replica of a 1971 Triumph Bonneville to put in shows, so modern touches (especially when they're more cost effective than stock-at-all-cost options) are something I have no trouble with.  A bike that starts easily and runs sweetly sells itself much more quickly than a cantankerous but period correct trailer queen.  One's a motorcycle, the other is art, and art is notoriously in the eye of the beholder.

One of the reasons I've always gravitated toward cheap and cheerful 80s and 90s Japanese restos was because the parts are usually easy to find, including hard parts from a breaker if needed, and they're as cheap as chips to buy because people tended to use them rather than put them up on a pedestal.

My first brush with 'vintage' (I think a 51 year old air-cooled Triumph from before the collapse of the British bike industry qualifies as vintage) has me wondering if my approach still works.  The cost of parts is much higher than more recent Japanese bikes and this particular Bonneville was half taken apart by a muppet who wanted to be in Easy Rider, so I'm constantly finding parts missing or incorrect.  I'm also struggling with missing non-metric tools after having owned metric bikes my entire life.

When I'm reading Practical Sportbikes I enjoy the articles on DIY and the stories of scratchers who got a machine put together with their own hands.  When they run one of the 'specials' articles where it's a rich guy with clean hands throwing money at a project, I lose interest quickly.  Classic Bike Magazine is similar.  When they're talking about an owner keeping an old machine running on ingenuity and guile, I'm all in, but the minute it's a millionaire adding to his collection with another bespoke machine put together by someone else, I've lost interest.

I just finished Guy Martin's new book, Dead Men Don't Tell Tales, and Guy ends the latest one talking about trying to find what makes him happy.  This requires a fair bit of self awareness - something that most people don't have.  Guy's particularly difficult in that he will often act on an urge that turns out to be incorrect, but, as he says in the book, he's evolving.

There's a scene in Guy's Garage where Cammy, his professional race mechanic mate, knows how to fix the car they're working on but Guy has his own ideas and keeps bashing away at it wrong.  Rather than push the point, Cammy backs off and waits for Guy to realize he's using the wrong tool for the job.

Guy is critical of Cammy for being slack in his approach to work in the book, but I'm left wondering if the truth isn't somewhere in between:  what looks like a lack of effort from Guy's point of view is actually a better use of his energy from the professional race mechanic's point of view.  There's more to all this than just jumping in to the physical labour, you need to be exercising the grey matter too.

What I'm taking from this latest round of Guy Martin media is that you're more likely to stay engaged with and finish big projects if they make sense to you.  To that end, I spent yesterday working out why the kickstarter on the Bonneville wasn't working (the muppet had put it in backwards).

The goal is still to have gone through the whole bike and have it back in working order without breaking the bank.  The amount spent on it matters less than whether or not the project is in the black.  If a functional '71 Bonneville is worth about five grand, then that's what I'll work to on the budget, while keeping an eye on what engages me most about all this:  putting a sidelined bike back into service again... and then riding it!

This morning I'm looking at Motogadget's mo.Unit Blue and considering how to best tackle a 51 year old wiring loom that looks to be in good shape but should probably get rebuilt if dependability is the goal.  An ignition powered by bluetooth on a smartphone is just the kind of steampunk anachronism that a riding focused buyer would dig.  That it's also invisible means it won't hurt the look of the bike (the only change is the ignition key isn't there).

Got into rebuilding the Amal carbs only to discover the muppet who took them apart before didn't install any of the air slider hardware for the choke, so now I'm hunting for hard parts for 51 year old carbs... in a pandemic.  Note my anemic imperial socket wrench set.

Ready to go and then stopped - neither carb has the air slider or hardware in it.  I'd normally call around to the local breakers, find a donor set of carbs and then keep them handy for situations like this.  That isn't an option with a 51 year old British bike.

It's coming along - slower than I'd like, but it's coming along.  When it seems too much I remind myself why I'm doing it: one day soon that engine will turn over for the first time in decades and shortly after that I'll be out riding the thing!