KA100 seized piston

Hi All,
I had a piston failure when running in my engine and had a slight nipped up piston in the bore of a KA100.
It has a smear of aluminium from the piston left in the bore and want to clean it up before I hone the bore again. Has anyone got some suggestions on how and what to use to remove the aluminium from the bore please.
I obviously never run it in for long enough as it nipped up on first full throttle run.
I honed it with 220 grit hone maybe it was a bit coarse and might of needed more of a run in first as it had lost most of the coating on piston.

Q-tip and muratic acid. Be careful to not get any in the ports and of course take suitable precautions for using a strong acid. You’ll likely be able to pick some up at a hardware store.


1 Like

As James said the Muriatic acid will dissolve the smear of aluminum.

I am questioning the situation you are explaining that led to this though. Did this happen on a fresh rebuild? I would be concerned something else is amiss.


Thanks James & Robert I will go and get some muriatic acid and clean it up.
I had only just run it in on DYNO then went to do DYNO pulls and it nipped up, tuning was ok fuel I used was 3 weeks old mixed synthetic maybe this was the cause but I did shake it well first and it was stored in air tight container, never been a problem before.
Piston clearance was 0.11 so wasn’t to tight.
Do you think it is ok to run in engines using full synthetic oil?

I think it depends on what you are using. I have had excellent results with Amsoil Dominator and I know many use the suggested Motul.

Could you explain what you mean by nipped up?

I am not an engine builder but I have a person that I trust to do rebuilds. I had a problem last year where a freshly rebuilt top end that was broke-in and run on a dyno stuck a piston after 1 gentle lap on the track. we could never determine why. It is possible the piston had a defect. What kind of a hone do you use?

I use a Sunnen hone j55 stones 220 grit in a drill press as the hone with liquid pump for honing oil. Motul Synthetic was the oil I was using, main thing I’m concerned about is my choice of 220 grit maybe the 220 grit hone maybe to coarse, not sure what others use with success.