New Piston brands, have your say.

Shelby-Right · 2026-02-11T22:30:44-0700

Please can you add a Comment on the new piston brand you have used for any bike engine, had any issues, clearance issues, nipping up at recommendated bore size., finish, strength, had any ring lands fall off etc.
Hepolite
GPM not sure if that correct, those Italian ones.
Omega forged
Wossner forged

My Triumph T160 I will get a set one day, stock pistons are likely cast, but are still holding at the occasional 8000rpm blast,
Cheers.

Elfix · 2026-02-11T23:20:45-0700

Well, I predict this will be less than useful to anyone-

I had three sets of Wossner forged pistons for my 1995 Honda RS250 4-corner seize upon loading even after an extensive warm up and pre heating of the motor. The factory Honda pistons (NLA) are cast and evidently expand less when exposed to load.

The Wossner were absolutely gorgeous pistons and were exactly the same size as the Honda units… but I never got a full lap out of the bike with them.

I have previously run Wossner pistons in multiple 4-stroke machines with excellent results. The running clearance in the RS250 is clearly insufficient for the Wossner forged units… but I’ve no idea what the clearance needs to be to make best power once everything is hot.

This experience was frustrating enough to lead me to park the Honda and switch to the 750 class on another bike.

concours · 2026-02-12T06:05:59-0700

Elfix said:
Well, I predict this will be less than useful to anyone-

I had three sets of Wossner forged pistons for my 1995 Honda RS250 4-corner seize upon loading even after an extensive warm up and pre heating of the motor. The factory Honda pistons (NLA) are cast and evidently expand less when exposed to load.

The Wossner were absolutely gorgeous pistons and were exactly the same size as the Honda units… but I never got a full lap out of the bike with them.

I have previously run Wossner pistons in multiple 4-stroke machines with excellent results. The running clearance in the RS250 is clearly insufficient for the Wossner forged units… but I’ve no idea what the clearance needs to be to make best power once everything is hot.

This experience was frustrating enough to lead me to park the Honda and switch to the 750 class on another bike.

Long, long history on forged pistons not suitable in 2-strokes. Both "Seizeco" and Wossner claim " new, magic alloy formula" that expands like cast. BS.
You are correct, few cast alternatives now.
Yambits offers these Pro-X, I have them in the RZ350, working great.

Yambits : for Yamaha bikes

This Mitaka piston kit comes complete with the piston, piston rings, gudgeon pin and circlips. Well renowned as one of 'THE' makes of piston to use on these models, so you can buy with confidence. Most users recommend filing the small tang from the skirt, this tang is only needed if used on the...

yambits.co.uk

I had to resort to Wossner in my H2. No cast available (except for ebay junk not fit for purpose.)

concours · 2026-02-12T06:10:48-0700

Elfix said:
Well, I predict this will be less than useful to anyone-

I had three sets of Wossner forged pistons for my 1995 Honda RS250 4-corner seize upon loading even after an extensive warm up and pre heating of the motor. The factory Honda pistons (NLA) are cast and evidently expand less when exposed to load.

The Wossner were absolutely gorgeous pistons and were exactly the same size as the Honda units… but I never got a full lap out of the bike with them.

I have previously run Wossner pistons in multiple 4-stroke machines with excellent results. The running clearance in the RS250 is clearly insufficient for the Wossner forged units… but I’ve no idea what the clearance needs to be to make best power once everything is hot.

This experience was frustrating enough to lead me to park the Honda and switch to the 750 class on another bike.

What clearance did you set them up to?
The RZ350 twin factory book specifies .0025" piston clearance.
.0035" should allow your forged pistons to survive, albeit rattly.
I know, it sucks.

concours · 2026-02-12T06:34:07-0700

As for Britbike, I've used several sets JCC Pistons, with great results.

marshg246 · 2026-02-12T06:40:58-0700

I've been using Hepolite sets for a few years for Norton. Today, the sets include JCC pistons and Federal Mogul rings. At one time, before Hastings quit making them and stock dried up, the Norton sets came with Hastings rings.

When I last used a Hepolite set for Triumph they were JCC/Hastings - I don't know what rings they include for Triumph these days. Hastings still makes them for Triumph as far as I know.

kommando · 2026-02-12T09:21:29-0700

John Healy confirmed the JCC pistons were an excellent copy of the OEM pistons made by old Hepolite including the alloy mix. Less so on their rings but that's why the New Wassell Hepolites use JCC pistons and non JCC rings.

Fast Eddie · 2026-02-12T09:40:47-0700

kommando said:
John Healy confirmed the JCC pistons were an excellent copy of the OEM pistons made by old Hepolite including the alloy mix. Less so on their rings but that's why the New Wassell Hepolites use JCC pistons and non JCC rings.

Don’t mention the rings !

My T140 was rebuilt with Wassell pistons, which seem very good to me. However, the bike burnt oil, and the engine oil was getting badly polluted by combustion blow by. I fitted some Goetze rings supplied by Andover and both problems were solved.

Elfix · 2026-02-12T10:59:53-0700

I was using whatever the Honda factory clearance was- which was clearly not enough. The RS cylinders were nickasil coated aluminum so enlarging them was not an easy option. The sticking pistons never damaged the bores- those cleaned up easily and you couldn’t tell anything had gone wrong!

As it was an old F2 bike the clearance was pretty tight to begin with- to be expected on a 250 that made well over 70hp at the tire. Later factory versions of this same engine allegedly made just over 100hp- astounding!

When it was on song and happy it was a fantastic ride- it was bonkers light, weighing less than most dirt bikes.

Shelby-Right · 2026-02-12T11:46:11-0700

Elfix said:
Well, I predict this will be less than useful to anyone-

I had three sets of Wossner forged pistons for my 1995 Honda RS250 4-corner seize upon loading even after an extensive warm up and pre heating of the motor. The factory Honda pistons (NLA) are cast and evidently expand less when exposed to load.

The Wossner were absolutely gorgeous pistons and were exactly the same size as the Honda units… but I never got a full lap out of the bike with them.

I have previously run Wossner pistons in multiple 4-stroke machines with excellent results. The running clearance in the RS250 is clearly insufficient for the Wossner forged units… but I’ve no idea what the clearance needs to be to make best power once everything is hot.

This experience was frustrating enough to lead me to park the Honda and switch to the 750 class on another bike.

That's a bummer, the 4032 forged have less clearance than the real race pistons 2018 ?, Type maybe another. 001". For a trident they are about 3 times the price.