Author Topic: Piston choice - Hepolite or JP?  (Read 1304 times)

Offline Steverat

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Piston choice - Hepolite or JP?
« on: 03.10. 2018 17:31 »
I am in the lucky position of needing to buy a pair of +0.040" A10 pistons, and find the Hepolites offered at less than £100 whereas JP are over £200 (Feked and others). Can you enlighten me as to the difference in value? I always thought Hepolite, as an OE manufacturer, would be more highly valued, obviously not. What is so good about JP? Is there a problem with Hepolite?

Thanks for your views
Steve

1951 BSA A10 - now returned to Germany
1972 Triumph T100R Daytona
1924 B-S SS80
1965 Triumph SH Cub
1960 AJS M18CS

Offline mugwump

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Re: Piston choice - Hepolite or JP?
« Reply #1 on: 03.10. 2018 18:02 »
Hepolite only in name now, unfortunately. They are TAIWANESE made, and come in a deliberately aged looking and authentic packaging. However, they have served me well and I'm assured they are good quality. BUT, the rings supplied with them are crap so if you go with these get some decent rings, which are readily available from somebody like Hastings or Thorntons etc.
I have also had good experience with Gandinis in other bikes.
No idea about JP.
See what others have to say.

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58 Ariel Huntmaster]

Online RDfella

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Re: Piston choice - Hepolite or JP?
« Reply #2 on: 03.10. 2018 20:20 »
Original Hepolites were the benchmark for others. Always used them in the engines I rebuilt (incl many marine diesels) in preference to OEM.
When I recently rebuilt my GF I had a set of + .040 Hepolite, but sadly, when boring the cylinders, found the muppet who bored it previously hadn't got the cylinders perpendicular. Had to go to + 060 to clean up, so was obliged to buy fresh pistons. Ony ones I could find were JP. Came in very cheap cartons and the pistons themselves look cheap. They work, but then my GF isn't run in yet. Not overly impressed whith what I saw. I've heard Gandinis, mentioned by mugwump, are good, but never seen them in the flesh. Have Feked still got the original Hepolite + 040 pistons they bought off me when I had to go to 060?
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Offline Steverat

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Re: Piston choice - Hepolite or JP?
« Reply #3 on: 03.10. 2018 20:49 »
I'll ask, thanks

1951 BSA A10 - now returned to Germany
1972 Triumph T100R Daytona
1924 B-S SS80
1965 Triumph SH Cub
1960 AJS M18CS

Offline berger

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Re: Piston choice - Hepolite or JP?
« Reply #4 on: 03.10. 2018 21:02 »
i have not been to the pub, I put those Taiwanese pistons in mine but with Gandini rings and they are doing very well, from the oil ring groove all the way down to the bottom of the skirt it looks like you could use them to saw fire wood compared to the smooth finish of old original pistons , but they are standing up to the abuse I give them *shh* >:D

Online Dipstick

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Re: Piston choice - Hepolite or JP?
« Reply #5 on: 03.10. 2018 21:07 »
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.

'78 XT500, '59 A7, '79 XS650, WR450F

Offline Steverat

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Re: Piston choice - Hepolite or JP?
« Reply #6 on: 03.10. 2018 21:13 »
i have not been to the pub, I put those Taiwanese pistons in mine but with Gandini rings and they are doing very well, from the oil ring groove all the way down to the bottom of the skirt it looks like you could use them to saw fire wood compared to the smooth finish of old original pistons , but they are standing up to the abuse I give them *shh* >:D

berger where did you manage to buy the Gandini rings?

1951 BSA A10 - now returned to Germany
1972 Triumph T100R Daytona
1924 B-S SS80
1965 Triumph SH Cub
1960 AJS M18CS

Online ellis

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Re: Piston choice - Hepolite or JP?
« Reply #7 on: 03.10. 2018 21:21 »
Andover Norton stock them.

Address: Unit 4 Brunel Gate, Portway West Business Park, Andover SP10 3SL
Phone: 01264 359565


ELLIS

Offline berger

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Re: Piston choice - Hepolite or JP?
« Reply #8 on: 03.10. 2018 22:20 »
Steverat I seem to think it was burton bike bits and they hadn't got + 40s at the time of asking but within 14 days they got them to me, they are well made and all marked for fitting the correct way, even in a nice box and each in its own packaging with a diagram and instructions-------- also pre gapped

Online groily

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Re: Piston choice - Hepolite or JP?
« Reply #9 on: 03.10. 2018 22:25 »
When I needed some for one of my AMCs, the only available option at 8.5:1 was JPs.

I think the critical thing is bore dimensions.  JPs don't come with machining data if I remember right.  If memory serves, about 5 thou skirt clearance was what we went for on 72mm bores. I haven't touched the engine significantly since building it up in early 2013. Doesn't use much oil, is very free revving and goes really well..

If I was faced with using them in the A10 I wouldn't be unhappy. That day cometh, as the +40s in it have done umpteen thousands of miles over 10 years+ and I've already given them one new set of rings.

My latest new ones are GPMs (Gandinis) for a notrun, just a few weeks back. I used them because they're what's available (and what was in there before) but I would have been happy enough to go JP there too if necessary..

Prices for the GPMs  and JPs were comparable at £175+ taxes for the latest ones, and about £160 five years back for the JPs.
Bill

Offline bl**dydrivers

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Re: Piston choice - Hepolite or JP?
« Reply #10 on: 04.10. 2018 02:32 »
I’ve read up so many horror stories with reproduction pistons that I searched for NOS BSA +40 pistons and was lucky to have found them. But will need new piston rings as the NOS ones have some corrosion on them and best to play it safe.

Offline John alexandrou

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Re: Piston choice - Hepolite or JP?
« Reply #11 on: 04.10. 2018 10:31 »
I bought a set of Hepolite Pistons and rings for my A10 Roadrocket, the rings didn’t bed in properly and forced a second reopening end strip and rebuild, I bought a new set from an Italian manufacturer and the difference was like chalk and cheese, bedded in nicely no smoke etc.,

Offline Slymo

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Re: Piston choice - Hepolite or JP?
« Reply #12 on: 04.10. 2018 13:48 »
I found the JP Piston I bought for a B44 rather heavy and the rings would simply not bed in. I found on looking at various forum posts that this was a common experience. I ended up with a Hap Jones Piston from the States (although the Piston was made in Japan) which settled in a treat. It may be that there was too much oil around for the JP rings to bed in as I had head gasket issues at the same time but I would suggest that you use the lightest wipe on the bores on assembly.
NZ

Offline BSA_54A10

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Re: Piston choice - Hepolite or JP?
« Reply #13 on: 04.10. 2018 14:09 »
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 .
Bike Beesa
Trevor

Online groily

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Re: Piston choice - Hepolite or JP?
« Reply #14 on: 04.10. 2018 16:11 »
Yup - the weight of the JPs and the quality (or lack of) of the rings were two worries I had when doing my AMC motor, having heard exactly what's been said here.
In that case, the 8.5:1 JPs at +20 weighed 23 grammes more than the originals at standard bore and 7 point something:1. Not a big difference in that case I didn't think, but not a perfect apples to apples comparison either. How much heavier is a JP for a B44 I wonder, just as matter of interest? Maybe it's a 'singles thing' . . .?

The rings didn't give me any problems either luckily, and 20K kilometres down the road, no reason for concern. To start with, I was definitely very edgy just waiting for trouble to strike. Now, I give it full beans through the gears just so I can hear the sound of a high-revving comparatively shortish-stroke twin with an amplifier for an exhaust.

So dunno - am I just lucky? Or are some versions of JPs better than others? Or does it come down to getting those bores sized spot-on to suit by people used to fitting the things, and just maybe helped by being ultra-careful for the first few hundred km on what was not only a new pistons/rebore/valves/guides/seats/cams/followers job, but also a brand new crank and forged rods  . . . all of which cost a bloody lot of beer vouchers. (There were none left to make the cycle parts half as nice, but that's Ok.)
Bill