Which pistons are available for my ariel

[john.mitchell]

The low compression 6.2:1 was used in the HT. I am told they are useable in Black Ariels with an insert in the small end.

[david.anderson]

Further to my post on page 3 regarding the expansion of pistons when hot, I have recently measured the expansion of Omega and JP pistons. My procedure was the same. First measure the piston (this time at 17C and in the oven for 1 hour at 250C. The pistons went in with an original Ariel 6.8. The results are:
Original Ariel VH6.8 piston +.012 (same as original measurement)
Omega 8.5-1 Piston +.013
JP 9-1 +.011
That makes the JP the lowest expanding piston.
David

[nevhunter]

I would say the JP is a silicon alloy which gives less expansion. It is also heavier and the thickness of the walls on large oversizes particularly makes them a lot heavier than some of the genuine pistons. Even if you rebalance the extra weight makes them vibrate more as thinks going up and down can only in part be balanced by things going round and round. 65% is the factor OTA. nev

[john.nash]

got this from Peter Kemp, our single spares chap

These are the new Ariel VH pistons,.
These are as per original weight, have a nice compression, are finished oval, and available only from Super single spares.

Also in stock are Square four pistons

All BRITISH MADE

Pete's contact info is on our website:
http://www.arielownersmcc.com/members ... pares.html

[john.nash]

(from my own point of view .. well done Pete mate .... availability of 500 pistons has been an issue for a long time. Yes we can use JP/GPM but we really needed something with the correct expansion and weight)

[Paul Slootheer]

I agree with John. I have seen these Omega pistons. Pete brought some with him when he attended the last International West Kent Run. Very nice pistons indeed, and more important with the right weight like the Heplex or Hepolite ones and... made in England! Well done Peter!!
Cheers, Paul

[david.anderson]

While the new omega piston may be the same weight as the original piston it is a lot shorter in height. I have previously tried short pistons in the long stroke Ariel and found a lot of increased engine noise due to piston slap, particularly as the bore wears a little. I have also seen/heard short pistons used in a Harley where piston slap noise was very bad. It would be good if someone could report on the engine noise from these, particularly as the bore wears a little.
David

[nevhunter]

One problem with the VH/VG pistons is the proximity of the Gudgeon pin to the lower ring. This gives high load to the skirt at the top and that is where it will wear most. Short pistons will rock more., but many modern pistons are much shorter but they run in Nikasil bores most times or are liquid cooled motors so run less clearance and run quieter. The other thing is there is less area to dissipate the heat to the cylinder wall. Nev

[Delharding]

Hi, why haven't you asked Singles spares, Pete has excellent VH pistons on the shelf! Derek.

[alan.moore]

I am in need of a VH piston. Has anyone any first hand advice they can give on te fitting of either a JP or the omega sold through single spares as pictured above.

I am torn beteween the extra weight of the Jp and the short skirt on the Omega