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.
https://www.doityourself.com/stry/10-muriatic-acid-safety-tips
2 Likes
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.
2 Likes
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.
What oil ratio were you running when it seized?
Motul Kart Grand Prix 100% synthetic mixed at 16:1
Our rule sets (SKUSA) call for Elf 909 mixed at approx 20:1. 1 bottle oil in 5 gal fuel. Some local racing is Motul 2T. Haven’t seen a bunch of KAs sticking motors on it…
Now the shifter guys…oh geeze. They are always sticking one on whatever they run. 
Lately I have been running Vrooam syncorse 2T oil mixed at 16:1, burns really clean hardly leaves any carbon at all on piston.
Haven’t had any problems with this oil yet
but would be interested to know if anybody has run it in there shifter karts as it sounds like the shifter karts would be a good test for oils
I prefer to run in my ka100’s using castor 927. Once the ring is seated, I then switch over to synthetic