Eastern pistons

[MG]

Brian, thanks for the update.
I'll ask again in 7-8months, okay? 

[olev]

Gday,
I've got hold of a set of 40 thou o/s pistons for the A7.
They seem to be about 8:1 CR.
The numbers on the packet say 67/1446 (Made in England)
The numbers on the piston say '67/1447 BSA'  '1mm OS'
then G over 46 inside a circle.
The closest match is Bacon's book which lists a 67/1442 as an 8:1 for 1958 - 1962.
They are solid skirt and weigh 7 gm more than the 7.25:1 originals.
Any thoughts on what I've got here? genuine BSA?
and why do they have oil holes into the gudgeon bushes if the pin isn't supposed to turn in the piston?
cheers

[Brian]

67-1446 is the part number and 67-1447 is the casting number. 67-1446 is correct for a 1mm or +.040" oversize 8-1 piston.

As for the brand, what was on the boxes? JP and GPM and the pistons I bought all come in clearly marked packets with the brand name on them.

I am not sure what pistons are made in the UK if thats whats on the packets. Hepolite come in distinctive boxes. All the genuine BSA pistons I have come across have the piled arms stamped into the top.

The gudgeon bushes have oil holes to let the oil in as the pins turn in the bushes.

Maybe you could post a photo of the packets the pistons came in and someone may recognise them.

[MG]

Hepolites woud be split skirt, so are JPs.
The GPMs are solid skirt, and as far as I can remember they're marked with metric o/size values.

[KiwiGF]

Hello Brian I have just got std size flat top pistons from British only Austria and wondering how I can tell who made them as there are no manufacturing markings etc they look the same as yours And were circa 170nzd delivered

I got a few other prices for JP pistons NOS hepolites etc (all more than double the cost) but taking everything into account these pistons seemed the best bet being new lowish compression and lightweight

[KiwiGF]

Hello Brian a quick check revealed the BOA gudgeons are 003 underside of 0.75 and the rings all have a 022 gap which will increase to over 025 when the barrel is honed to suit the pistons the max gap i think is 013

 I just wondered if I am unlucky and BOA have sent the wrong parts or if your parts are the same

The pins fit Far too easily into the pistons w/o warming them up and are also loose in my billet rods :-(

[BSA_54A10]

I fitted the pistons today and discovered one problem, the rings. They had way too much end gap, .020". I had a set of Hepolite rings so I used them. Now I have a spare set for a STD or +.010" engine. Otherwise it all looks good.

No you do not have a spare set of + 20 rings.
It is a common fallacy that you can grind down a set of oversized rings to fit a smaller bore.
You can't.
The curvature will be wrong and the rings will apply very uneven pressure on the cylinder wall causing rapid oval wear of the bore.
You might get away with it in an emergency, like to get the bike back on the road fro the BSA National Rally ( cheesy plug ) but you should replace them with the correct size as soon as you get home.

[Brian]

When I bought mine the pins were the correct size but the rings had way too much end gap, I cant remember exactly what the end gap was but it was at least .020" or more, I didnt use the rings but fitted a Hepolite set I had.

If your pins are loose in the rods dont use them. When you say billet rods I take it they have no gudgeon bush, the pins run directly in the rod. Do you have a set of original pins that fit the rod correctly, if you do heat a piston and see if the pin will push in. If it does you could use the pistons with different rings and pins. This of course means you would have to buy new pins and rings which probably makes the whole thing more expensive, alternatively you could send them back.

The ones I put in my engine have done just on 1,000 miles now and so far so good. It seems like they will run ok but time will tell what the wear will be like. I have a set of Hepolites ready to put in if these ones cause any trouble.

[KiwiGF]

Hi Brian thanks for that I have some barely used pins and I could use them as they fit fine but I think I have the time to get BOA to replace the Pins and rings I'll post the results of that here......

I was going to buy pistons from JP but on this forum posters said JP rings were rubbish... so i don't feel so bad about the BOA rings being wrong I was sort of expecting it.

Apart from comments JP pistons were heavy and the rings rubbish the final straw was that it was cheaper to buy JP pistons from UK distributors like "red lizard" than direct from JP and even when I pointed that out to JP they refused to budge on price. JP also wanted twice the $ to ship from Aus to NZ than UK suppliers charge to ship to NZ!

I bought the SJ billet rods from thunder engineering Of the UK $550 nzd delivered and they supply SRM so I guess they are the SRM rods but cheaper also they arrived in NZ within a week and look great and yes there is no bush in the small end the only downside of these rods is the barrel cut outs will need to be widened by about 6mm as they are wider than OEM rods

I am not sure whether to simply take a grinder to the barrels or get the honer company to do it with a mill a slight concern with doing this widening is that the barrels have liners

[KiwiGF]

After a couple of weeks of waiting British Only Austria could not get a reply from the makers of the pistons (alledgedly a Taiwanese outfit) and they have asked me to return the piston as a set as they cannot replace just the faulty rings and gudgeon pins.

In addition they reckon they cannot "meet my requirements for this price"

My requirements being usable rings and gudgeon pins!

Pretty poor of British Only I reckon. I cannot recommend buying this type of piston set from them based on this experience

[terryk]

Does anyone know how much weight difference there is between JP pistons and hepolite?

[KiwiGF]

I asked JP and they gave the weight of their A10 std bore pistons as 351grams for the 6.5:1  and 343grams for the 7.25:1

I have quite a collection of hepolites and non branded pistons and the hepolites are the heaviest and much heavier than the BOA pistons mentioned above (using balance on ruler on nail method)

I have no way of measuring the weight in grams of the hepolites though - sorry

[KiwiGF]

Hi Terry- firstly BOA refunded me for the duff piston sets I got from them and also refunded me all the freight involved so good on them!

After quite a few quotes including very high prices for NOS hepolites I bought JP pistons from Draganfly- odd it's cheaper to have them sent from aus to the uk and then back to nz! Draganfly had nil stock so I had to wait for them to do all the traveling.

Anyway using a metal ruler and nail as a balance I can tell you the JP pistons std bore flat tops part no 0652 are slightly lighter than the hepolite pistons listed below. Interestingly I found the difference about equal to the difference between a gudgeon pin with a straight bore as supplied by JP and some tapered bore pins I had.

I hope this info is of some use- I was surprised the Hepolites were heavier than JP as I've been told the Hepolites are direct equivalent to the OEM BSA pistons, and also I've been told that a general problem with JP's is that they are much heavier than almost any other brand, but that does not seem to be true in the case of A10 pistons

11062 +060
11412 +020
11787 +060
Chinese? std

[BSA_54A10]

Apart from comments JP pistons were heavy and the rings rubbish the final straw was that it was cheaper to buy JP pistons from UK distributors like "red lizard" than direct from JP and even when I pointed that out to JP they refused to budge on price. JP also wanted twice the $ to ship from Aus to NZ than UK suppliers charge to ship to NZ!

Australia Post is now just about the most expensive O/S postal system in the world so do not blame JP for that, Julia Gillard yes, JP no.
As for unbranded pistons I never even think of using them.
If a product is good then the maker will want to tell the world about it, if it garbage they won't.
If a supplier sells quality pistons then they will sell them in branded boxes so the world will know that they sell good quality pistons.
If neither want their name to be associated with the pistons it is most likely because they want you to forget where you got them from before they failed & totaled your engine

[chaterlea25]

Hi All,
Just as an addendum to this thread the previously "no name " pistons are now "branded" Hepolite
and sold/distributed by Wassels,
HTH
John O R

[a101960]

Oh dear, oh dear. oh dear.