Scratched inside of piston sleeve, advice.....

[Stevin]

my hele stalled in flight, I got home and opened the motor up to find that one of the springs that hold the piston to the arm popped off and got wedged in between the piston and sleeve. This was only very fast. after taken it all apart I can see it mde a single scratch on the inside of the piston sleeve. I used high grit sand paper to smooth it a bit but I can still feel it with my finger. As far as I can see the piston moves inside of it pretty easily. Is this anything to worry about. Should I or not use this piston sleeve, will it cause the ring to rip up or anything?

[BaconRaygun]

I don’t have any experience with nitro helis... but I am no noob to nitro as I was deep into nitro cars for 11 years.
My $.02, change that piston/sleeve!

Happy flying man!

[Airsporter1st]

Originally Posted by Stevin

my hele stalled in flight, I got home and opened the motor up to find that one of the springs that hold the piston to the arm popped off and got wedged in between the piston and sleeve. This was only very fast. after taken it all apart I can see it mde a single scratch on the inside of the piston sleeve. I used high grit sand paper to smooth it a bit but I can still feel it with my finger. As far as I can see the piston moves inside of it pretty easily. Is this anything to worry about. Should I or not use this piston sleeve, will it cause the ring to rip up or anything?

I doubt it will rip up anything, but it will leak gasses past the ring. I would change the sleeve and, if any damage to the piston, that too.

[mr008]

If the scratch is deep enough that you cant get rid of it with some lite sanding, you will lose compression thus less power out of the engine. Now that you have it apart just replace the bearings , sleave and ring and u pretty much have a new engine.

[Mercuriell]

Try it and see, if it wont start or isnt flyable you have your answer. Sounds like it might be OK, worth a try as its a lot of $ for a new piston, sleeve and ring

[Himilou]

yup, if you have the $$ replace the sleeve, otherwise it should run but with a slight loss of power from gas blowby.

[McKrackin]

Shouldn't lose a bunch of power but it will lose some.

If you can actually FEEL the scratch,I'd replace it.
It will run ok but not great.

[Punkin71]

I would replace the sleeve for sure, but here's some advise to make sure it doesnt happen again.

When you do put the new circlips in the piston make sure the open area of the clip is facing directly to the top or bottom of the piston.Top or bottom, doesnt matter either way, this will make sure the pistons' up/down forces cannot cause the clip to slip out of the groove also make sure the clip is fully seated in groove.

[Tag1260]

I'd try it. May not make a bit of difference. Or it might but you'll never know unless you try. You actually may have done more damage trying to fix it than if you had left it alone. But again, give it a try. You've really nothing to lose if it doesn't work.

[McKrackin]

Originally Posted by Tag1260

I'd try it. May not make a bit of difference. Or it might but you'll never know unless you try. You actually may have done more damage trying to fix it than if you had left it alone. But again, give it a try. You've really nothing to lose if it doesn't work.

As for fixing a scratched cylinder sleeve...

I use Never Dull most of the time.
I stick a drill bit in the can and hit the trigger on the drill. This balls up some of the fiber on the bit.
Then run the drill with the ball of Never Dull very slowly in the cylinder...

I have also used a brake cylinder hone.
DO NOT put the hone in a drill...We're not boring it out.
Just put the hone in the cylinder and turn it by hand about five times.

Never Dull is best as it cleans very well and cross hatches the wall without enlarging the bore.

In an engine this small though,if you can actually FEEL the scratch,it's bad and not really repairable...Maybe not too far gone to use but not repairable.
To clean it to the point that you can't feel the scratch will open a ring gap that is WORSE than a hole in the piston.
It would even open enough to allow the ring to spin on the piston and then the whole top end and rotating assembly is junk.