Oil control rings

[Mark W]

Having my kz900 for 15 years he timing chain and stuff needed to be replaced,so far so good.During the rebuild the bottom oil ring got caught and bent I find out that these are aftermarket high compression pistons 155 on each cylinder the only mark on these is a c in the middle of the valve cut outs.I find that the ring depth of 3.1 and height of 2.7 with a radius of 69.4 is not a standard size.I have been to all the obvious places with no luck.At the moment my only choices are getting the bottom ring slot remilled to except another one or replace all 4 pistons!!!Has anyone any thoughts regarding this?

[zed1015]

Pic's may help identify the make of the pistons.
There are usually markings inside the piston on the skirt or gudgeon pin boss.
Rings are usually available once that info is known.

[Mark W]

At the moment I have a smoking no4 cylinder,as a temp measure I have straightened it out and put it back in.This was a temporary measure as I knew I would have to take it apart anyway ,I am becoming an expert at that.Will start again on Sunday and hopefully solve before the weather turns.Will let you know when I have more information.Pictures of bike in happier times

[warren3200gt]

Example, wiseco

[ADRIAN H]

Having my kz900 for 15 years he timing chain and stuff needed to be replaced,so far so good.During the rebuild the bottom oil ring got caught and bent I find out that these are aftermarket high compression pistons 155 on each cylinder the only mark on these is a c in the middle of the valve cut outs.I find that the ring depth of 3.1 and height of 2.7 with a radius of 69.4 is not a standard size.I have been to all the obvious places with no luck.At the moment my only choices are getting the bottom ring slot remilled to except another one or replace all 4 pistons!!!Has anyone any thoughts regarding this?

69.4mm is standard size for 998mm Z1000J pistons

[Mark W]

Standard size but unfortunately the ring dimensions for the oil control ring are different.So I can’t use the rings from the Z1000J.I am 3/4 through stripping the engine down again , should have the piston out of the block and try to find an identification mark

[Mark W]

Piston is out and any comments would be appreciated

[zed1015]

Those are Wiseco pistons.
10.25 - 1 compression.
The 'C' denotes the ring type = XC which are in common use by Wiseco, MTC, JE and probably others.
Pistons taper inward toward the top so you need to measure at the bottom of the skirt or the cylinder bore which will likely be 70mm - 1015cc but if they are 69.50mm then Eastwood Racing in London has rings for them.

https://www.wiseco.co.uk/products/2736x ... t-69-50-mm

[Mark W]

I have measured at the top 69.5 and the skirt at 70 ,Is Eastwood racing the best place to go ?

[zed1015]

I have measured at the top 69.5 and the skirt at 70 ,Is Eastwood racing the best place to go ?

Then they are 70mm - 1015cc pistons.
Eastwood Racing is a UK Wiseco importer so probably the best place to start with the search.

[Mark W]

I have spoken to Eastwood racing and success!! They had 1 set in stock so thanks to Zed 1015 they are indeed 2736x rings 1mm top ring,1.2 middle ring 2.8 oil control ring

[ADRIAN H]

I have spoken to Eastwood racing and success!! They had 1 set in stock so thanks to Zed 1015 they are indeed 2736x rings 1mm top ring,1.2 middle ring 2.8 oil control ring

That’s a result, pleased for you.

[Mark W]

After getting 70mm rings from Eastwood racing and taking piston up there!They reckoned it is not a wiseco piston but I purchased them anyway,the oil control ring was close but no cigar.Having previously spoken to Dave at Z power he sent me a couple of used oil control rings from a 1000 just to try,at this point I could do with a break.They arrived and were the correct depth but a tiny bit narrower 0.1 mm so at the moment have used the original as the top ring and put the 1000 ring at the bottom.I have rehoned the barrel and have assembled most of the engine and should have it running by the end of the day.If this fails might try a 1 piece oil ring that I could get made.

[Mark W]

Hopefully this is the last post on the subject,it started it ran and didn’t smoke.The lesson learnt is careful putting the pistons in it can cause 3 months of headaches