Hi Alastair,

Firstly, welcome to the Forum.

collection of 1968 and 1969 bonnie parts on a TR6C frame.
large oil leak from somewhere near the base gasket on the engine that may have been from the pushrod tubes

Things to bear in mind:-

. Late 1960's Triumph 650's, most parts are common to all versions in the range - Triumph was very adept at creating "ranges" with only a few different components on different models.

. Nevertheless, between the '68 and '69 'model years', Triumph made changes particularly to the pushrod tubes sealing; none of the parts from the two years - from the tappet guide blocks in the cylinder block to the cylinder head - are interchangeable; to stand any chance of leak-free PRT, any engine builder has to pick a year and ensure all the parts around the PRT are from that year. Fwiw, cylinder head present and being the most expensive part to change, its 'year' usually dictates the choice.

. If find you have a '68 cylinder head, imho thank whichever deity you worship, just ensure all the other parts are '68.

. Otoh if you're imho unlucky (and I mean that advisedly) enough to have a '69 cylinder head, Can Of Worms Alert ... The '69 PRT changes were a severe balls-up, that were subsequently 'modified' (imho bodged) again by Triumph - you need to look at a '71 650 parts book for the additional O-ring but also be aware subsequent experience suggests other changes. Ask on the Forum for details as you approach that stage of any engine rebuild?

Engine is likely to need a rebuild and at the moment I'm trying to decide how far into the engine and gearbox to go.

Wise to go at least to the top of the crankcases: you'll need to measure the depth of the cylinder head PRT recesses - to determine whether the head is '68 or '69; you'll need to examine the PRT, seals and tappet guide blocks; lift the block to ensure the oil leak isn't due to any 'step' between the gasket mating surfaces of the crankcase halves.

plan to replace the engine case bolts, as I don't like screwing old bolts into alloy in case I ruin it.

You can just as easily ruin an engine case with a new bolt ... Blind holes this old always have an accumulation of swarf, old gasket goo, etc. in the bottom, open holes have corrosion where a screw has never been; screw a slightly-longer new bolt on to/into that'll bugger the component. Components this old, I always run a #3/Bottom tap into/through every thread irrespective whether I'm fitting a new bolt or refitting an old one; blind hole, I put grease in the tap flutes, any debris sticks to the grease.

Bear in mind you'll run into a mixture of threadforms, especially as you have a mixture of '68 and '69 parts ... E.g. '68 case threads are usually BSF (British Standard Fine) whereas '69 are always UNC. However, threads into the cylinder block will be British Standard Cycle (helpfully abbreviated to "CEI" by Triumph ). If you don't already, as well as a way of measuring diameters (micrometer or vernier calliper is better than steel ruler), I advise a set of screwpitch gauges for measuring threads-per-inch.

main issue I'm finding is that as you disassembly everything you have to keep making choices about what to keep and what to replace.
My latest find is that the fork stanchions, while serviceable along the length that moves inside the fork leg, are quite pitted and rusted above that line (of course this is covered by the boot).

A potential factor to consider particularly with fork stanchions is: if you replace, they will (should) be to '70-on standard, when Triumph hard-chromed 'em as standard; seals should last longer and the action should be better (relatively) due to lower friction. Whether you reuse or replace, I advise greasing or waxing (beeswax furniture polish) the areas of the stanchions not swept by the seals.

Nevertheless, stanchions (used or new) and slider bushes must be measured with micrometers (inside and outside) to ensure the clearances are still within those in the relevant Triumph 650 workshop manual.

intend to update some parts
roller bearings in the steering

If you must, be careful which you choose - to paraphrase Animal Farm, not all "replacement" taper-rollers are created equal ... Also consider what Triumph did '71-on on - they had Hoffman produce a 'caged ball' race that simply fits in place of 20 loose balls top or bottom - Klempf's British Parts. BEARING, STEERING, CAGED

cad plate all the bolts
assume if I wire brush them then they'll rust pretty fast

They'll rust pretty fast after you cad-plate them - cadmium is pretty hopeless once a wrench is used ... I started buying stainless more than forty years ago, no idea how much it's cost but never regretted it.

Free-to-read online Triumph parts book library
Free-to-read online Triumph '63-'70 Workshop Manual

Don't be afraid to ask questions on the Forum, anyone answering was also once a newbie, the stupidest question is the one not asked.

Hth.

Regards,

 

Hi Alastair,

Firstly, welcome to the Forum.


Things to bear in mind:-

. Late 1960's Triumph 650's, most parts are common to all versions in the range - Triumph was very adept at creating "ranges" with only a few different components on different models.

. Nevertheless, between the '68 and '69 'model years', Triumph made changes particularly to the pushrod tubes sealing; none of the parts from the two years - from the tappet guide blocks in the cylinder block to the cylinder head - are interchangeable; to stand any chance of leak-free PRT, any engine builder has to pick a year and ensure all the parts around the PRT are from that year. Fwiw, cylinder head present and being the most expensive part to change, its 'year' usually dictates the choice.

. If find you have a '68 cylinder head, imho thank whichever deity you worship, just ensure all the other parts are '68.

. Otoh if you're imho unlucky (and I mean that advisedly) enough to have a '69 cylinder head, Can Of Worms Alert ... The '69 PRT changes were a severe balls-up, that were subsequently 'modified' (imho bodged) again by Triumph - you need to look at a '71 650 parts book for the additional O-ring but also be aware subsequent experience suggests other changes. Ask on the Forum for details as you approach that stage of any engine rebuild?


Wise to go at least to the top of the crankcases: you'll need to measure the depth of the cylinder head PRT recesses - to determine whether the head is '68 or '69; you'll need to examine the PRT, seals and tappet guide blocks; lift the block to ensure the oil leak isn't due to any 'step' between the gasket mating surfaces of the crankcase halves.


You can just as easily ruin an engine case with a new bolt ... Blind holes this old always have an accumulation of swarf, old gasket goo, etc. in the bottom, open holes have corrosion where a screw has never been; screw a slightly-longer new bolt on to/into that'll bugger the component. Components this old, I always run a #3/Bottom tap into/through every thread irrespective whether I'm fitting a new bolt or refitting an old one; blind hole, I put grease in the tap flutes, any debris sticks to the grease.

Bear in mind you'll run into a mixture of threadforms, especially as you have a mixture of '68 and '69 parts ... E.g. '68 case threads are usually BSF (British Standard Fine) whereas '69 are always UNC. However, threads into the cylinder block will be British Standard Cycle (helpfully abbreviated to "CEI" by Triumph ). If you don't already, as well as a way of measuring diameters (micrometer or vernier calliper is better than steel ruler), I advise a set of screwpitch gauges for measuring threads-per-inch.


A potential factor to consider particularly with fork stanchions is: if you replace, they will (should) be to '70-on standard, when Triumph hard-chromed 'em as standard; seals should last longer and the action should be better (relatively) due to lower friction. Whether you reuse or replace, I advise greasing or waxing (beeswax furniture polish) the areas of the stanchions not swept by the seals.

Nevertheless, stanchions (used or new) and slider bushes must be measured with micrometers (inside and outside) to ensure the clearances are still within those in the relevant Triumph 650 workshop manual.


If you must, be careful which you choose - to paraphrase Animal Farm, not all "replacement" taper-rollers are created equal ... Also consider what Triumph did '71-on on - they had Hoffman produce a 'caged ball' race that simply fits in place of 20 loose balls top or bottom - Klempf's British Parts. BEARING, STEERING, CAGED


They'll rust pretty fast after you cad-plate them - cadmium is pretty hopeless once a wrench is used ... I started buying stainless more than forty years ago, no idea how much it's cost but never regretted it.

Free-to-read online Triumph parts book library
Free-to-read online Triumph '63-'70 Workshop Manual

Don't be afraid to ask questions on the Forum, anyone answering was also once a newbie, the stupidest question is the one not asked.

Hth.

Regards,

With respect to your description of British thread definitions, my old owners repair manual for my 1969 Bonneville Tr6 called them "Whitworth" threads. I think you meant British Standard Whitworth. Just an observation. Nice thread!

 

Finishing the nuts and bolts on your bike really comes down to how you plan to use the bike and how it will be stored. All my vintage bikes are stored in a heated garage and almost never ridden in the rain and certainly not if there is salt on the roads for the winter. So, I usually hit them all with a wire wheel and then use them as is. I have restorations that are going on 30 years old and the bolts still look like they did the day I did them. No rust returning or anything.

Rob

 

Finishing the nuts and bolts on your bike really comes down to how you plan to use the bike and how it will be stored. All my vintage bikes are stored in a heated garage and almost never ridden in the rain and certainly not if there is salt on the roads for the winter. So, I usually hit them all with a wire wheel and then use them as is. I have restorations that are going on 30 years old and the bolts still look like they did the day I did them. No rust returning or anything.

Rob

Hi Rob, I did a "poor man's refurb" to a 1970 TR6R barn bike last winter. I de-rusted hardware in Evaporust and wire wheeled fasteners to give them a little polish. The bike looked nice and tidy, but still looked like a rider. In the meantime, I had used muriatic acid to clean the interior of the tank, then poured the spent liquid into to an empty paint stripper can. The can was placed on a wooden shelf under a work bench, to be dealt with later. Well, about a week later I noticed an acrid odor in my garage, but didn't pay much attention to it until I went to move the Triumph off the lift...every un-plated fastener had turned a bright rust color. The acid had leaked through a seam in the steel can and soaked into the wood shelf and puddled on the garage floor, resulting in a corrosive atmosphere in the garage. Boy, did I learn a lesson about the usage and storage of muriatic acid. Since then I have been replacing the rusted items bit by bit, creating a lot of extra work for myself. Needless to say, every time I look at one of the rusted bits I realize what a dumbass I was!
-Dave

 

Hi,
The engine strip question is easy, you strip it until you can clean out the sludge trap; unless the engine is known to you and you know it has already been done recently.

Do not be tempted to attack your nuts with a wire brush— you will end up in hospital.😊

regards
Peg

 

I'm working on a "Bonneville" that is never going to be a show bike as it's a collection of 1968 and 1969 bonnie parts on a TR6C frame. I want to get it serviceable from an engineering stand-point. I would have left it as-is and just done smaller bits of work but unfortunately there was a large oil leak from somewhere near the base gasket on the engine that may have been from the pushrod tubes (looked more like the base gasket though).

I've decided to try to fix up the bike along the lines of how an owner might have been able to back in the day. In other words I'm not stripping every item and vapor blasting or powder coating. Instead I'm aiming for an economical restoration to usable condition.

View attachment 825633

That's a great "survivor" you have there, @alastair1969 . Refurbishing to mechanical soundness is always the best "first step" in acquiring a bike like this. That way, you know the core bike is running properly and reliably, and the chassis, suspension, and brakes are operating as they should for best performance.

Apart from "beefing up" the engine with a big bore kit or spiffy whirly bits for no apparent reason, you can go in any direction once the basics are up to snuff. Same goes for suspension and brakes; properly fettled original-spec stuff should be more than ample for the average rider, and even for advanced riders that know their limits. These WERE "SuperBikes" of their day!

Bottom line: HAVE FUN!

 

Hi everyone, I just wanted to say a big thank you for all your helpful responses. These are massively helpful to a novice like myself. Very much appreciated and I'll keep everyone updated on how things move along with this bike. Cheers!

 

On the other hand, if as it is on my older bike the cycle thread bolts use the “Whitworth” nut sizing system you will definitely need some “Whitworth“ spanners.

 

I took a look at the cylinder head casting mark, and it look like it is from 1967. The crankcase is stamped with a 1968 number, from early in the 1968 range. I don't know if the head came with this engine, but I guess it's likely there would be a crossover period when existing '67 heads would be put on early '68 engines.

Can anyone tell me whether I'm going to run into any issues with the pushrod tubes? Were there changes from 1967 to 1968 that I would need to be aware of?

 

Hi Alastair,

1967
cylinder head casting mark
crankcase
1968 number, from early in the 1968 range
guess it's likely there would be a crossover period when existing '67 heads would be put on early '68 engines.

"1968" with "range" indicates only a Model Year, doesn't always correspond with the calendar year - as a rule-of-thumb, the BSA (Triumph's parent company at the time) accounting year ended on June 30th, works would switch to building the following model year's bikes sometime within the following three months. So a crankcase with a "1968 number, from early in the 1968 range", the engine was almost-certainly built during the 1967 calendar year.

Otoh, the cylinder head's casting mark is a calendar year. Aiui, the two lines above the "67" indicate February but Meriden (in common with most of the British automotive industry?) hadn't embraced "just in time" component delivery and use ...

going to run into any issues with the pushrod tubes?

As I posted earlier, the big changes around pushrod tubes were for the start of the '69 model year.

To check the head you have, read Vintage Bike Magazine » Push Rod Tubes comparing:-

. the different depths of the pushrod tube recesses in pre-'69 and '69-on heads;

. the length of the pushrod tubes you have with the different pre-'69 and '69-on lengths.

Were there changes from 1967 to 1968 that I would need to be aware of?

Unless you find '67 model year parts, not a concern.

Be aware also that, although the head has a 1967-calendar-year casting date, it's a casting date, the casting would've been machined before any possibility of incorporating it in an engine. Also, the '67 and '68 650 parts books, the part numbers for T120 twin-carb. and TR6 single-carb. heads are the same.

Nevertheless, another Can Of Worms is parts inside '68 rocker-boxes ...

Meriden changed rockers during the '68 model year, plus the assembly order of rockers, plain washers and spring (Thackeray) washers should've been changed:-

. If you look closely at rocker-box illustrations in the '68 650 parts book and the 650 Workshop Manual (.pdf page 57, marked "B7"), you'll see the illustrated assembly order of plain washers and Thackeray washers is different ...

. The Workshop Manual drawing specifically illustrates rockers with an oil hole in the centre of each ball that fits in the top of the corresponding pushrod; these are early '68 rockers but the illustrated assembly order of plain and Thackeray washers is wrong for them ... the assembly order for these rockers is as illustrated in the parts book (a Thackeray washer against one side of each rocker).

. Otoh, if your parts collection has later rockers - don't have an oil hole in the centre of each pushrod ball - the assembly order in the workshop manual illustration is correct BUT some of the parts listed in the parts book then aren't correct ... Another place maybe post as you approach that part of engine assembly to receive the mind-numbing detail?

Hth.

Regards,

 

Hi Alastair,

"1968" with "range" indicates only a Model Year, doesn't always correspond with the calendar year - as a rule-of-thumb, the BSA (Triumph's parent company at the time) accounting year ended on June 30th, works would switch to building the following model year's bikes sometime within the following three months. So a crankcase with a "1968 number, from early in the 1968 range", the engine was almost-certainly built during the 1967 calendar year.

Otoh, the cylinder head's casting mark is a calendar year. Aiui, the two lines above the "67" indicate February but Meriden (in common with most of the British automotive industry?) hadn't embraced "just in time" component delivery and use ...


As I posted earlier, the big changes around pushrod tubes were for the start of the '69 model year.

To check the head you have, read Vintage Bike Magazine » Push Rod Tubes comparing:-

. the different depths of the pushrod tube recesses in pre-'69 and '69-on heads;

. the length of the pushrod tubes you have with the different pre-'69 and '69-on lengths.


Unless you find '67 model year parts, not a concern.

Be aware also that, although the head has a 1967-calendar-year casting date, it's a casting date, the casting would've been machined before any possibility of incorporating it in an engine. Also, the '67 and '68 650 parts books, the part numbers for T120 twin-carb. and TR6 single-carb. heads are the same.

Nevertheless, another Can Of Worms is parts inside '68 rocker-boxes ...

Meriden changed rockers during the '68 model year, plus the assembly order of rockers, plain washers and spring (Thackeray) washers should've been changed:-

. If you look closely at rocker-box illustrations in the '68 650 parts book and the 650 Workshop Manual (.pdf page 57, marked "B7"), you'll see the illustrated assembly order of plain washers and Thackeray washers is different ...

. The Workshop Manual drawing specifically illustrates rockers with an oil hole in the centre of each ball that fits in the top of the corresponding pushrod; these are early '68 rockers but the illustrated assembly order of plain and Thackeray washers is wrong for them ... the assembly order for these rockers is as illustrated in the parts book (a Thackeray washer against one side of each rocker).

. Otoh, if your parts collection has later rockers - don't have an oil hole in the centre of each pushrod ball - the assembly order in the workshop manual illustration is correct BUT some of the parts listed in the parts book then aren't correct ... Another place maybe post as you approach that part of engine assembly to receive the mind-numbing detail?

Hth.

Regards,

This is a 69 or 70 head. The casting was done late 67, but was pulled from the stack of castings and machined, probably in mid or early 68.

 

Thanks Stuart, that's extremely helpful information. I'll definitely post as I get closer to that point.

Quick question for people getting bolts Cad-plated: I see lots of pictures of piles of bolts getting sent off. How do you ever know where these go again once you get them back? I've been trying to mark all the bags of bolts I'm taking off so I know where they came from. But it is appealing to me to just send them all off and have them come back properly coated.

Thanks for all the help, really appreciate it!

 

It's a chore. It got easier for me after the 5th or 6th one, I really should have made a scaled visual I.D. chart, page by page from the parts book. I'll probably never have time or inclination to do that now...

 

Hi Alastair,

getting bolts Cad-plated: I see lots of pictures of piles of bolts getting sent off. How do you ever know where these go again once you get them back?

's a chore.

Mmmm ... consider ... when you get 'em back all shiny, line 'em all up by, say, length, diameter, hex. size; put all the same length and diameter bolts in one bag, all the same-diameter nuts in one bag, etc. Each bolt, screw, nut and washer has a part number, look it up in Greg Marsh's Fastener Database, that'll return you thread major diameter and form, length (usually UH - Under Head), head shape. When you know the part number of one fastener in a bag and you know they're all the same in that bag, you know the part number of 'em all in that bag, mark the part number on the bag.

'68, the vast majority of fasteners 1/4" major diameter and larger were originally British Standard Cycle thread on the ... errr ... cycle, mostly British Standard Fine thread on the engine, with the odd Cycle and British Standard Whitworth thread thrown in - same hex. size for the same major diameter irrespective of threadform, just different numbers of tpi (although 1/4"BSF engine case screws have the same 26TPI as 1/4" Cycle ).

Fasteners smaller than 1/4" major diameter were originally BA ("British Association", itself an abbreviation, for British Association for the Advancement of Science). The commonest is 2BA, that looks very like 10UNF and M5 but is not interchangeable with either, don't be tempted unless you like extracting small broken 10UNF or M5 bolts from expensive-to-replace components ... damhikt ...

Otoh, don't be surprised to find UNF threads in the fork yokes, it became standard there during '67. Petcocks and oil tank drain are British Standard Pipe, none of which are denoted by thread major diameters ... ... but do have the same hexs. as other British Standard fasteners.

Also don't be surprised to find UNF bolts and screws into corresponding nuts instead of Cycle, as UNF is still available in US hardware stores.

Hth.

Regards,

 

Hi,

This is a 69 or 70 head. The casting was done late 67

Depends on the interpretation of the two vertical lines above the "67":-

. if it's just two of a potential twelve lines, as I posted earlier, two lines probably indicate February;

. otoh, if it's the number "11", it might be November ... or the foundry might've used week numbers, in which case it was probably sometime in March ...

This is a 69 or 70 head.

This is speculation looking like fact.

The decider with this head is whether the casting was subsequently machined as pre-'69 or '69-on, for the completely-different pre-'69 or '69-on pushrod tubes and seals, that also dictates the correct tappet guide blocks in the cylinder barrel base.

Nothing the OP's posted so far shows the pushrod tubes/seals recesses in this head, to determine whether the casting was machined for pre-'69 or '69-on PRT and seals. The only way the OP'll determine that is as I posted earlier:-

read Vintage Bike Magazine » Push Rod Tubes comparing:-

. the different depths of the pushrod tube recesses in pre-'69 and '69-on heads;

. the length of the pushrod tubes you have with the different pre-'69 and '69-on lengths.

Regards,