View Full Version : top-end rescue: the acid option?

04-23-2015, 07:08 PM
Hi there,
Is there anybody out there with experience on cleaning uppiston smear of the nikasil bore of rotax 122 stock barrels? I have heard thatdilute HCL can work well but would like to hear it from someone who has beensuccessful with the rotax barrel. I wouldnít bother normally as I want to dropthe 140cc italkit in but PJME still donít have them, I donít fancy spending ona stock barrel and Iím not leaving the bike dead waiting. I will look intoelectroplating and honing costs but Iím guessing theyíll be up there. The onlypitting to the barrel is two small spots on the front of the cylinder but theyíreboth below the ports so Iím figuring that itíll still have good enough compressionup top where itís needed, so long as I can get the aluminium cleaned off well. Iknow I can get in there with some 1200 grit but I thought Iíd look into theacid option too.

The bike is a 2012 full power with only 1800kms. Looks likethe seize may be due to the monkeys who fitted a giannelli system to the bikefor the previous owner (at unbelievable cost) but didnít sort the jetting so itwas running way too lean Ė but might possibly have also been an air leak at thereedblock gasket.

I have had a good look on the forum but can't spot any existing discussions.

Any wisdom gratefully received. Now to have a look on theforum for porting advise Ė it looks like some time with a dremmel could help.

04-25-2015, 10:34 PM
Yeah I have just done this repair with hydrochloric acid bought from the local hardware.
I didn't dilute it and I just used a cotton bud which took a few applications.

Unfortunately the plating was damaged from the seizure but as it's below the rings at BDC I'm still going to use it with a new piston.
I will clean up the edges of the plating where the damage is when I get the correct grinding tips.

A friend has just cleaned up a RS 125 Honda barrel using the same acid without drama.

04-30-2015, 03:01 AM
Thanks Morad,
I cleaned most off with 800 grit then used a small amount of HCL like you with a cotton bud and bingo, the remainder stripped off easily. Then gave a tidy up with 1200 grit and job done. Good to know.