Piston choice - Hepolite or JP?

[bsa-bill]

does it come down to getting those bores sized spot-on to suit by people used to fitting the things

yep most good shops given one of the  piston you intend to use should get it right

[Dipstick]

It was before I discovered this great forum, I bought a set of JP's from a local dealer in Holland. Those were properly packed in a JP carton box so I do not recognise the complaint as mentioned in the previous post of RDfella.   No idea what the quality is....
Anyway, I bought them and have to install the pistons otherwise I am throwing away a lot of money 
Fingers crossed.

If they are the Aussie made JP's you have do not under any circumstance fit them with the original rings.
They will take near 1000 miles of careful running in before they seal.
Toss the rings on evilbay some idiot will buyt them and fit HAstings, Cord or whateveer your favourite ring is .

Yes they're made down under...

[bsa-bill]

do not under any circumstance fit them with the original rings.

now your going to tell us there upside down  (sorry old joke, just had to be said tho)

[Sluggo]

I have posted frequently on many forums about Hepolites and aftermarket pistons, so dont recall if I recited my screeds here or not in other discussions but Ill try to hit the high points and move on.

Hepolites were a OEM supplier of a cast piston.  Keeping in mind CAST being an operative word.  Generally okay and revered by many, I have used many sets and sold even more.  However I never placed them very highly as some peoples prices may suggest.  (There is some fanboys out there of them)  I still have a few sets in original EARLY packaging so, Surely the early types.  Hepolites over the years had different packaging so you can guess-timate the era of manufacturing by its packing.   The original company was bought up by a US company, they did nothing with it, then broke it into pieces and sold off. There is other vendors now making poor quality parts under that name, I believe under license.   Poor quality is a relative term because I never felt the originals were never more than a cheaply made part, however that low benchmark sunk even lower with the knock offs.

### I grew up building hot rod American V8s...  So a cast piston was a cheap part and not worthy of any self respecting engine builder.  Forged pistons were the minimum benchmark, But economies of scale are much different, And I have had car guys getting into classic British were shocked at some of the prices for pistons. For an approx comparison some years back I ordered a set of Cast Small Block Chevy 350 pistons for a grocery getter.  Less than $100 for 8 pistons, pins and rings.  For a set of much better Hypereutectic Was $160 and premium Forged was $275  FOR a FULL SET of 8!   I had a guy ask about Original Hepolites for a 1961 Triumph Bonnie and he was incensed at the price at the time of $220 for a set of 2.  (He opted for some cycle crafts I had for $90.00)   Now days, some are using all kinds of interesting materials as manufacturing has evolved.  A lot of discussion about Billet, and unthinkable before, but apparently its working out great.  MAP cycle is selling Billets for a range of applications.  Good reports I hear.  ###

Now, when using Hepolites of the original company I have seen a great deal of quality variables.   Pistons are graded and the better ones are matched up, When you turn them over NOS should have small painted dots.. green, red, blue etc.  This means that L-R they are somewhat consistent.  Castings can vary widely so they pair up sets to match.  However its not uncommon to get a set that varies considerably by weight.  Up to several grams.  They can also vary by sizing. CONSIDERABLY between L-R and some Hepo's are absurdly mismatched to proper dimensions.  So, when boring a cyl,, Its mandatory to label them L-R and hand fitted to each bore to correct dimensions as the piston ODs vary with Hepos in most cases.

Verify yourself,  Throw them on a scale and measure with mics & calipers.  Math is Brutal!

With Hepo rings,, again depends upon era manuf,, Some were quite good, (Considering)  However later years not so much.

I have NO experience with JP. However I find the expansion joints on the skirts shocking!  Holy hell that would keep me up at night!   I have seen many decades of mayhem on the Nortons where such joints were a sure fire way to seperate the crown of a piston from the skirts with much damage. Even the later versions with just the holes would break with regularity.  Many pictures online of blown up Nortons with these and the INOA tech digest expressly warns about this.   I have heard of similar on other makes.  Although I have seen a FEW race motors with holes drilled in the thrust face skirts for lightening, But in general a piston is like an egg,, It derives its strength from its integrity of the shell structure so a big slot, seems counterintuitive.    Other than some 2 strokes have never seen that pencil out. (Expansion joints)

Now for 2 decades I was a huge fanboy of CycleCraft pistons.  For a casting, they were excellent quality.  The finish and casting quality was excellent. More importantly I found very consistent piston weights L-R and dimensionally they were so consistent I never found any out of spec.  In some apps.. BSA A65 they were heavier than originals for example.. So rebalancing is important, But I like to balance everything so a minor issue.   However the supplied rings were garbage.. I always used Hepo rings, Hastings or a few others.
I only found one instance of the piston weights being off in 25 years of using them and we caught it early.  I believe that was an anomoly.  I DID find the supplied pins varied but we always weighted them and machined the IDs of the pins to get a consistent weight.  The supplied clips are a spring type and depending on what shows up, I never had a problem but in many cases I used special circlips I ordered for piece of mind.  (There was a raging argument on a NotRun site about bad circlips and grooves)

So, When I was building a LOT of motors (Mostly Triumphs) I would take in 4-6 cyls at a time. (20-40-60-80 in a few cases)  and drop off one set of pistons for each size with my cyl guy.  The consistency of the cycle crafts was so good, I never had an issue with sizing.  If it was for Hepolites??  hell no!!  We carefully controlled each cyl and the pistons to get the holes sized exactly.

I only built a few Motorcycle engines with high end forged pistons, as its a different world than car engines.  The reality is few people actually race or push these vintage bikes hard enough to justify it, so Cast pistons are usually adequate.  However when I hear someone gushing excessively about a Cast Hepolite being the top of the game its amusing.  Its still JUST a casting. And in the world of metallurgy a casting is subpar to other materials.

**One note on sizing.   I still have some old dealer stock with 10 thou increments, but its very hard to find pistons and rings in those ranges.  Back in the day they were supplied in 10 over, 20-30-40-50-60-70 and even 80 over.   I have run Triumph 650s with 80s with no issues and high mileage covered because there was enough meat in the cyl.  However I had a few cyls that were scrap at 60.   Nortons twins the cyls were so irregular you take a serious risk at even 20 over, 40 is exceptional and 60 is a miracle! (Dirt inclusions, dross, casting voids and cracking are the usual rejection issues)
Manufacturers typically only offer ins 20-40-60 these days unless you can find some old dealer stock, then HOPE there is matching rings.   ALSO note over the years, some pistons changed Ring designs,, which is a whole different topic, But the ring grooves HAVE to be checked they are suitable for the rings and vice versa
Check ring groove WIDTH and DEPTH!

I have had conversations with some of the largest US wholesalers and its painful for them to stock pistons for the more common BSA-Norton-Triumph  as to get pistons made now requires huge orders in each size to get them done.  Often these wholesalers will work together.  (MAP-JRC-Walridge-British ONLY-and Healys operation-Coventry Spares).   You guys are not riding enough and ordering enough.  It can take YEARS to sell off enough pistons to justify a re-order.     BSA A10s are considered so obscure very few people will bother to stock parts for them.  BSA A7???  Ha!  Good luck with that!

[Sluggo]

Just to clarify supply chain mgmt..

The cycle crafts dealer prices were around $45-55 per pair w/ no rings but included pins & clips, Retail varies by seller by typically $80 a pair.  A comparable pair of Hepolites were retail around $160-220  this is for a Triumph 650 twin and a few years ago.  But that should give you an idea.

I know directly the largest wholesaler was having a hard time getting stock from Cycle Craft because CC was doing 10,000+ piece orders for most Asian manufacturers so it was laughable when Bill called to order 100 pairs for each size. (20-40-60) and thats for faster moving stock like Triumph.  Unit  BSA and Norton twins stock moves even slower.  As the largest dealer supplier in the US (Wholesale only) Bill asked me what I though he was moving on Norton twins.  My guess was not even close.   He had sold under 20 pairs of Norton pistons in a year  (You guys arent riding enough)   So, the MINIMUMS for pistons orders keeps going up, and demands down.  Tough market.   As a financial reference,, its poor economy to tie up thousands and thousands of dollars in poor moving stock.  So Dealers would go in on group buys for pistons.

Now, CC seems to have severed production of vintage bikes.  I am seeing products instead branded by EMGO, They look the same.. and assume they are okay.   But here is my advice.  If you guys want to see your beloved Preunit BSAs on the road at all,, You need to stock up on consumables because the supply is fading fast.  I just dont see the incentives to produce such small batches of pistons, valves, rings, and bearings that are proprietary for BSA applications that have no cross over to other makes and models.

My friend Charley who does all my cyl work specializes in 2 strokes and you can often repurpose a cyl or sleeve for obscure applications but not so much on vintage  British 4 strokes.

Heck, at the DGR ride was chatting with a Buell owner and I own some Tube frame and XB Buells and he asked what am I doing for parts,, as some are now already UN-OB-TAIN-IUM  so the writing is on the wall you guys!     

Look at it this way...If you shuffle off this mortal coil before you use the parts, make sure they are labeled and what they go to so your estate or family can sell the bike AND the spares to keep the machine operational, It also adds value.   Otherwise all these bikes will be just like that RUSH song about the Red Barchetta.

-----------------------------------------------------------
Music: Geddy Lee and Alex Lifeson
Lyrics: Neil Peart

My uncle has a country place, that no-one knows about
He says it used to be a farm, before the Motor Law
Sundays I elude the ‘Eyes’, and hop the Turbine Freight
To far outside the Wire, where my white-haired uncle waits

Jump to the ground
As the Turbo slows to cross the borderline
Run like the wind
As excitement shivers up and down my spine
Down in his barn
My uncle preserved for me an old machine –
For fifty-odd years
To keep it as new has been his dearest dream
I strip away the old debris, that hides a shining car
A brilliant red Barchetta, from a better, vanished time
Fire up the willing engine, responding with a roar!
Tires spitting gravel, I commit my weekly crime…

Wind in my hair –
Shifting and drifting –
Mechanical music
Adrenalin surge –

Well-weathered leather
Hot metal and oil
The scented country air
Sunlight on chrome
The blur of the landscape
Every nerve aware
Suddenly ahead of me, across the mountainside
A gleaming alloy air-car shoots towards me, two lanes wide
I spin around with shrieking tires, to run the deadly race
Go screaming through the valley as another joins the chase

Drive like the wind
Straining the limits of machine and man
Laughing out loud
With fear and hope, I’ve got a desperate plan
At the one-lane bridge
I leave the giants stranded
At the riverside
Race back to the farm
To dream with my uncle
At the fireside…

[RDfella]

Have to disagree with sluggo re Hepolite pistons. Maybe we’re talking different eras, but in the 70’s, 80’s and 90’s when I was building at least one engine (road cars, race cars, boats, m/cycles) a week, I almost always used Hepolite instead of OEM (ie Ford or any other manufacturer). Never had an issue. Yes, cast pistons for 2,500rpm diesels, road cars and cooking motorcycles, but forged for anything that might get a thrashing. In those days Hepolite led the way, not only in piston quality, but alfin cylinders, steel piston inserts and the like.

BTW, does anyone know the preferred balance factor for an A10? I didn’t bother with my recent rebuild as it’s only for road use, but I notice vibration starting around 2,700 (guess, no rev counter) that comes in fairly quickly and maintains the same to max revs (or at least as far as I’m prepared to push a motor with alloy rods). I remember when Chevrolet carried out testing on alloy rods. They only lasted a couple of million cycles – that’s around five hours at 7,000rpm. Aluminium fatigues and work hardens; witness the number of BSA rods that have exited the crankcase (mine, at one time, for example). Would never be my choice for a rod.

[muskrat]

G'day RD.
62 to 65% is the recommended figure.
I went a bit higher to 72% and it's pretty smooth up top (5-7000) but at 1-2000 she'll walk out the door.
Re alloy rods, I think BSA put a life span on them of 80,000 miles. I never had a rod go when racing the A7SS with 14:1 compression and revving to 7500. Lifted barrels and snapped cranks but never a rod.
Cheers

[RDfella]

Just to add to my last post, the fact our bikes have become classics should mean parts will be more readily available than they were a few decades ago, not less. As an example, I have a '46 Ferguson the family has had from new. It has the continental motor and when I rebuilt the engine in the early seventies parts were getting really hard to find. It was an old tractor, Ferguson wasn't interested any more, and by the time the eighties came around, nothing was available. When I needed some pistons, there was no chance. Eventually I found a set of four for a 50's Plymouth car that were the same, but 3 1/4" dia instead of 3 3/16". Ideal, as I could bore the liners + 060. Nowadays, forty years later, virtually everything is available. Pistons & liners (three sizes) exhaust manifolds, valves. Everything. Why? Because they are no longer old tractors, but classics that people are doing up, thereby creating a demand. I feel it is the same with our bikes. So much more is now available than was the case twenty or more years ago. Sure, some of the parts may be of questionable quality, but remember that twenty or thirty years ago thare were no parts at all.

[Steverat]

I have bought the new foreign Hepolite pistons but with NOS genuine British Hepolite rings to fit, all from Burton Bike Bits for £163.13 total.
Thanks for all your help and advice!
Steve

[Sluggo]

Have to disagree with sluggo re Hepolite pistons. Maybe we’re talking different eras, but in the 70’s, 80’s and 90’s when I was building at least one engine (road cars, race cars, boats, m/cycles) a week, I almost always used Hepolite instead of OEM (ie Ford or any other manufacturer). Never had an issue. Yes, cast pistons for 2,500rpm diesels, road cars and cooking motorcycles, but forged for anything that might get a thrashing. In those days Hepolite led the way, not only in piston quality, but alfin cylinders, steel piston inserts and the like.

BTW, does anyone know the preferred balance factor for an A10? I didn’t bother with my recent rebuild as it’s only for road use, but I notice vibration starting around 2,700 (guess, no rev counter) that comes in fairly quickly and maintains the same to max revs (or at least as far as I’m prepared to push a motor with alloy rods). I remember when Chevrolet carried out testing on alloy rods. They only lasted a couple of million cycles – that’s around five hours at 7,000rpm. Aluminium fatigues and work hardens; witness the number of BSA rods that have exited the crankcase (mine, at one time, for example). Would never be my choice for a rod.

When you were building these motors, what kind of anomalies did you find with piston weights and measurements when using Hepolites??    I have zero experience using them for anything other than Motorcycles so perhaps cars, lorries and locomotives were a different kettle of fish.  But for motorcyle applications I would measure them on a scale and see what the difference was L-R for weights.  I saw many with significant weight differences sometimes up to 2 grams. (often less but still significant)  I surmise that could have a significant impact on vibration wouldnt you agree? 
Usual fix was to take a die grinder and carefully use a carbide or sand paper roll and take some material off the undersides in non critical areas to even them up.
When it came to measuring, It was common to see big deviations from established specs, so back in the days manual specs usually were 3 thou piston to wall,, modern day much looser (4 to 4.5 thou) but when the OD of a piston exceeds those numbers, you will have a problem getting clearance right so either hand fit each piston to each bore, (Hone to spec) or turn down the piston exterior to spec.

As to cast vs forged,, I was illustrating that these are 2 different qualities and specs, However many owners dont know the difference or aware of that.  They go simply for brand name recognition.  However a Cycle craft made in Asia as a cast piston was in my experience vastly better quality at 1/3rd to 1/2 the cost to the OEM Hepolites.  Yet some persisted that the CCs were asian made junk.

I do agree with the alloy rods, valid point.  Stan Shentons Triumph Speed tuning quotes Triumph factory engineers as saying the life of a OEM Alloy rod was one race at race speeds.  However if a plodder and sunday driver,, many can get a lot of life out of a alloy rod with little worry.  If your machine is a significant investment new rods are a sensible expenditure.

BSA Goldstars are a prime example... While many in their heyday ran them competitively with the stock cranks and rods,, these days any sensible Goldie owner will opt for a Pearson Crank assy and Carillo rod, or many are using the ABSAF kit.  The value of a Goldie (And parts) makes anything else foolish economy.

[Sluggo]

Just to add to my last post, the fact our bikes have become classics should mean parts will be more readily available than they were a few decades ago, not less. As an example, I have a '46 Ferguson the family has had from new. It has the continental motor and when I rebuilt the engine in the early seventies parts were getting really hard to find. It was an old tractor, Ferguson wasn't interested any more, and by the time the eighties came around, nothing was available. When I needed some pistons, there was no chance. Eventually I found a set of four for a 50's Plymouth car that were the same, but 3 1/4" dia instead of 3 3/16". Ideal, as I could bore the liners + 060. Nowadays, forty years later, virtually everything is available. Pistons & liners (three sizes) exhaust manifolds, valves. Everything. Why? Because they are no longer old tractors, but classics that people are doing up, thereby creating a demand. I feel it is the same with our bikes. So much more is now available than was the case twenty or more years ago. Sure, some of the parts may be of questionable quality, but remember that twenty or thirty years ago thare were no parts at all.

Could & should vs reality is 2 different things.  If the demand is there, Sure,, someone will produce a product for it, However it all comes down to economies of scale.   While Vincents are not a common bike and generally considered rare, because they have some passionate owners you can nearly build a new Vincent from parts, albeit at an exorbitant price.   You can build a new 1969 Camaro, or Chevelle as barleycorn makes all new bodies and there is multiple suppliers for every nut bolt & assy, but again,,, at a very dear price.  Same with MG and Triumph sports cars.   The parts supply for POPULAR makes and models of vintage British is generally better than anyone has a right to expect and surprising really.   But thats only on models that have enough demand.   For example Lowbrow customs, one the largest online sellers for vintage bike parts does not stock ANY parts for a Preunit BSA.  They do have limited Unit BSA A65, A little Norton and a LOT for unit Triumphs, but only scattered parts for a Preunit Triumph.  No 441 or C15 single parts.
I know most of the major players,  Mark Appleton of BCS, Mike P at Walridge, Marino & crew at MAP, Bill of JRC, John of Coventry Spares, and only in passing that shifty character at British Only, Bob & his son Mike at Rabers parts mart (Now closed)  and they will all tell you the same thing about supply and demand,

While its amazing we can get ANYTHING at all,, Some may not like hearing it but Preunit BSA twins are not in the same ballpark and the demand is so low, we are fortunate that any one sells parts for them, and I dont see that improving.

If you think that is harsh,,, I have some Matchless bikes.  THOSE get no love at all.  Only true nutters have them and if it were not for the owners club and spares scheme, they would be totally extinct by now.  I have some friends who restored them and its very hard to even recoup 2/3rds of the expense when you sell one.

If you doubt that,. I have some G3 and G12 parts I would like to sell you.

[trevinoz]

Standard balance factor is 54%. 65% for racing.

[muskrat]

Yes thanks Trev. Why do I always go to the extreme?
Ah I know. Lots is good, more is better and too much is just enough!
Cheers

[berger]

I have just weighed 2 genuine STD BSA pistons and 2 +60 possibly made in Taiwan and I have a question I hope could be answered. BSA piston 8to1 comp stamped BSA 67/1443,. 210 point 4gms
also stamped 46/2/69
BSA piston number two BSA 67/1443  then  number 6.7/66
 weighs 212point 8gms
what do the other numbers mean??
other pistons +60thou one is 241gms and other is 239point 9gms , not very interesting but I have no idea what the other numbers mean on the genuine BSA ones , anyone know?

[Slymo]

Here in NZ we have always suffered from a scarcity of spares. EBay and t’internet have reduced the problem but what happens when you’re looking for something truly obscure pistonwise is you go to Franklin Engineering who for an economically viable (for them) price will make them for you bespoke from appropriate blanks. Alternatively you can find something that will match. I have a mate who runs a Hyundai diesel piston in his 30’s Panther 100 with unqualified success.