I have these fitted to my Z and they've covered around 4k miles.

 

Anyone else have these or has anyone heard of any detrimental issues regarding these pistons or the installation of these pistons?

 

Regards

 

Steve E

The most common/popular forged pistons fitted to the VG30 in the world.

 

There have been some known issues...but these all relate to a bad batch of circlips a couple of years ago.

There have been some known issues...but these all relate to a bad batch of circlips a couple of years ago.

 

Do you know the details or symptoms relating to the circlips?

 

Thanks

I think it was to do with the clips breaking or become unseated and jamming between the piston and cylinder wall.

I think it was to do with the clips breaking or become unseated and jamming between the piston and cylinder wall.

 

lol, that sounds fairly terminal....I don't have that.

 

I have a slight vibration at around 2800rpm which is only apparent on the overrun when bliiping the throttle. I can slowly rev the engine straight through the revs and get nothing...

 

I can't determine whether it's piston related, small end related or cam related but it's worse when cold and not so apparent when hot but a good ear can pick it up.

 

Apart from that, no other symptoms..

 

Any ideas?

a slight knock is usual and once warm and expanded it should quiten down, if its more of a rattle then id be more concerned.

 

problems with weisco are poor design circlip ie..If one is not installed properly and falls out or pings out, then you have a problem!

 

there was a bad batch of circlips which even weisco did not deny, however this was a one off, not a good one admitadly but was sorted

 

IMO im not a fan of them, but you dont want to hear that, and besides most people use them as there cheaper than majority of the rest. and 99% of the time there fine, i prefer arias pistons the circlip design is second to none and all circlips can be installed in seconds, and are solid.

I changed to wiesco after having a problem with JE. I had #6 piston pick up on the bore and JE wouldn't replace just 1 piston so I opted for the wiesco through Z1 who had a GB a few years back.

 

Back to the wiesco though...there are no unusual noises on start up and it's a very light rattle and not a knock. I can drive around below 2500rpm in any gear with no noise.

 

My guess it's a little piston slap at the top of the bore where there maybe slightly more clearance. This is probably harmless so I'll just have to see whay happens.

 

I'll also unplug the VTC solenoids and see what happens although I think my mechanic already tried this - idk.

ask Stu, SRRAE, not sure if he comes on here any more though.

ask Stu, SRRAE, not sure if he comes on here any more though.

 

yes, he had the known circlip problem

I changed to wiesco after having a problem with JE. I had #6 piston pick up on the bore and JE wouldn't replace just 1 piston so I opted for the wiesco through Z1 who had a GB a few years back.

 

Back to the wiesco though...there are no unusual noises on start up and it's a very light rattle and not a knock. I can drive around below 2500rpm in any gear with no noise.

 

My guess it's a little piston slap at the top of the bore where there maybe slightly more clearance. This is probably harmless so I'll just have to see whay happens.

 

I'll also unplug the VTC solenoids and see what happens although I think my mechanic already tried this - idk.

When did you buy the Wiseco's , as I know they redesigned them back in 2005 to reduce piston slap.

When did you buy the Wiseco's , as I know they redesigned them back in 2005 to reduce piston slap.

 

I have the wiesco that were built to Z1 specs. Z1 spent alot of time looking into the piston slap problem that alot of Z owners were having.

 

I haven't seen any negative feedback about these although I had heard of an isolated issue about circlips.

 

Steve

with such a short skirt and large diameter. im not surprised they slap.

maybe your liner is wearing, was the liner examined when the pistons went in, might be abit of ring chatter, is it at high or low rpm

Sounds like piston slap to me.

 

I'm surprised people still use circlips, we moved to teflon studs on the bikes 20 years ago.

Thanks guys.

 

If it's only a little piston slap then I can live with it as these pistons are much lighter than stock and the skirts are shorter.

 

It isn't as pronounced when the engine is hot and it's isn't apparent after the 2500/2800 rpm range so I'm lead to beleive that the expansion of the pistons helps with this.

 

I suppose there's always a downside to making modifications.

 

I'm used to engine noises with a daily diesel to drive and a 2stroke for my 2wheels...I wonder if that uses teflon studs :)

im very surprised the zed engine uses circlips. id check your bores arent oval as thats more likely to cause slap.

my GTti doesnt have circlips, the gudgeon pin is pressed in to the rod.

my RS125 had a teflon coated piston

With circlips you get a fully floating gudgeon pin which has its benefits, but when they are not done right then you have the downside of clips comming off and pins moving, wait till you work with articulated pistons, thats a nightmare.

 

You should be fine as long as you don't get the clips comming off and as has been said it sounds like a bit of piston slap, I get it at around 2k but it goes with very slight throttle.

im very surprised the zed engine uses circlips. id check your bores arent oval as thats more likely to cause slap.

my GTti doesnt have circlips, the gudgeon pin is pressed in to the rod.

my RS125 had a teflon coated piston

 

i thought you would of known the 300 uses circlips ;)