SOHC.co.uk Forums > CB350/400

Oil control rings too big for bore

<< < (2/3) > >>

SteveW:
I have just had a similar issue rebuilding the missus’s 1964 Vespa.
The new rings, even though they are the correct ones don’t fit.
Putting them in the bore to check the gap and they are perfect, however once they are on the piston you can’t fit it in the barrel.

I found that the new rings are thicker, ie the inside diameter of the ring is smaller so the ring sticks out further.

Checked with the supplier and they were the correct rings so no idea what was going on.

Luckily I have an engineer mate who managed to make a jig in his lathe and machined the inner diameter of the ring to the correct size.

Rings fitted perfectly after, engine runs perfectly.

AshimotoK0:
Just had a similar issue with Genuine Honda in sealed boxes rings for my 500/4.. all rings were dead on the correct ring gap except one second compression ring which actually overlapped in the bore. So I had to get onother ring set. I calculated that the ring was in fact a +0.50mm rather than the correct +0.25mm

Laverda Dave:
I'm going through the same problem at the moment with Hepolite pistons for the Triton rebuild. Namely the oil control ring. It fits perfectly in the bore and the gap is correct. However, once the spiral 'spring' if fitted into the Grove at the back of the ring it is impossible to compress the ring in the bore. It's not the piston but the spiral spring. The technical department at Hepolite (or should that be Wassel as that is who own Hepolite these days?) don't even respond to calls or mails!
Luckily the supplier who I bought the kit from is sourcing me some other German made rings as a replacement at their cost as they've had the problem before with Hepolite rings.
Hepolite are now only a brand name, the pistons are made by JCC in Asia for them.
Its very disappointing that Hepolite know there is an issue and do nothing to resolve it and instead are more interested in profits whilst leaving their customers to solve the problems without technical support or advice.

K2-K6:

--- Quote from: Laverda Dave on August 06, 2020, 11:30:04 PM ---I'm going through the same problem at the moment with Hepolite pistons for the Triton rebuild. Namely the oil control ring. It fits perfectly in the bore and the gap is correct. However, once the spiral 'spring' if fitted into the Grove at the back of the ring it is impossible to compress the ring in the bore. It's not the piston but the spiral spring. The technical department at Hepolite (or should that be Wassel as that is who own Hepolite these days?) don't even respond to calls or mails!
Luckily the supplier who I bought the kit from is sourcing me some other German made rings as a replacement at their cost as they've had the problem before with Hepolite rings.
Hepolite are now only a brand name, the pistons are made by JCC in Asia for them.
Its very disappointing that Hepolite know there is an issue and do nothing to resolve it and instead are more interested in profits whilst leaving their customers to solve the problems without technical support or advice.

--- End quote ---

For your application Dave have you considered Mahle pistons? and if they are available in suitable match. Always  been very good quality.

Has anyone put a caliper across the ring land diameter to see if there's any machining discrepancy there that could cause the problem? The rings don't generally sit hard up against the internal diameter once installed,  so essentially floating on the piston and centralized by the bore.

K2-K6:
For Dave, good discussion here https://www.accessnorton.com/NortonCommando/piston-weight.24435/  looks interesting within the British twins field.

Navigation

[0] Message Index

[#] Next page

[*] Previous page