NR57 failure

[barney]

Couple days back I had a piston failure on one of my 57,s I'm a bit gutted as it seems I can't get the piston separately making for a prohibitively expensive repair.

The failed motor is my much lower airtime one and was my 'good un'
I could have accepted it happening to my other NR which I accidentally cooked at 3DS. Ive since stripped that motor and replaced the ring/brg and is now performing superbly again which is a testament to it's build quality as it was damned hot as I was forced to fly out my 'Sets' ( the oil in the exhaust was crackling from the heat)

The offending engine has never been lean and run mostly around 1975 and a little at 2100 on 8:5 ratio meaning it's not working very hard at all and a piston or ring failure was completely out of the blue which surprised me.

Even stupider is NR supply a liner separately but not a piston!

I'm in two minds about this as the NR knocks spots of other big block motors in the power stakes but piston unavailability is not acceptable unless you buy a liner and ring with it

I ain't springing for a new motor for sure at the mo. Mmmmm












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[pgkevet]

I feel your pain

Best guess with mine is that after it's rebuild it never occurred to me to flush the muffler..all engine parts were flushed with carb cleaner, checked, oiled and re-assembled clean..but when the pressure nipple loosened I'm guessing it sucked debris left in the muffler from my previous damage and chewed itself up inside..

[barney]

The pressure nipple coming loose is a deathnell to most motors and would suspect that was your culprit.

Not sure if I'll move from NR at the mo as the performance is intoxicating and have 2 x mufflers to match + at £220ish a new NR is out and £140ish for a full rebuild is silly when a piston/ring/brg would have it running

[pgkevet]

The pressure nipple coming loose is a deathnell to most motors and would suspect that was your culprit.

Not sure if I'll move from NR at the mo as the performance is intoxicating and have 2 x mufflers to match + at £220ish a new NR is out and £140ish for a full rebuild is silly when a piston/ring/brg would have it running

I was loose rather than hanging..and I picked up on engine behaviour and landed with a hot one still running well. It just wouldn't restart after that. I can't see where the fragments came from within the engine.. as in no crumbled piston edges or skirt bits missing.. why i think the looser nipple changed muffler pressures and allowed cr*p to get sucked back..

But academic.

Have you tried emailing novarossi?

[barney]

I spoke to Luca (NR testpilot) can only be bought as the following normally.

Liner or Liner/Piston/ring or Liner/piston/ring/Conrod which is daft as piston is not available seperately making it uneconomical to repair. Ill drop them an e-mail directly but wont be holding my breath.

Brian

[Mike W]

Ouch Brian .. would have thought they would have sold the bits sep as most people dont need all the above at the same time ... Hope you get it sorted m8e

[barney]

We will see how good there after sales committment is. LOL e-mail sent directly

[raptorheli2]

fwiw mate, and don't take this wrong way. i've never thought the novarossi's when i've seen them were any diff/better than the other big blocks.....i maybe wrong.

if i was you i would get the ys56. i don't own one but i'm not liking the OS 55 i have so don't consider it i would say.

cheers

[barney]

Hi dude..was not overly impressed at the OS55's myself. (thinking about rear brgs as the 50 was bad enough) The YS its pricey as is the new NR (NR were £150 for a short time and should have got another back then but £200+ now is daft for a 50 class motor)

When the NR is on song its very very good even down as low as 1900/8:5 ratio on 20%/620 blades it makes a Hyper 50 feel dead. (Its not the smoothest of motors but I can accept that)

The NR/outrage HR1159 on 620's I really like as its just groovy and torquey making it pleasant to fly. At 2050 + pulls really hard. Just the idiot pilot who's a dumbass on the sticks mostly over pitching i.e me LOL

[pgkevet]

I ordered a YS56 today to replace my 50...we'll see how how long it takes me to kill that
But pricewise you can almost get a 90 for the 55 costs..if one could shoehorn one in...

Perhaps Novarossi would do the repair if they won't sell the parts??..but then again they might charge for all the unnecessary bits...
I found their manual quite off putting with all that talk about trying different shims and stuff.. I got enough trouble just tuning them normally without adding complications and the one guy locally with one spent more time fiddling that flying...

[Mike W]

Thats the only downside to the 55 Brian that I have found is that it eats bearings lol... Mind you changed first set at one gallon .. this set from my local bearing place has lasted over 2 gallon now so here's hoping lol.... Cant comment on the 56 as never owned one ... The NR does look a nice engine and some people have said it pulls like a 60 year old hooker ...

[electricsceadu]

i must have a good 55 mines had 13/4 gallons through it and i've still got its original bearing in it

[barney]

The first NR went about 6 boxes to its first brg

[barney]

OK Got the reply directly from NovaRossi today. They say the pistion is matched to the liner.

BUT...I say

1/If that is the case why do they sell just the liner by itself.

2/The motor is not an ABC and uses a ring to seal the cylinder

3/ The piston ring contacts the cylinder wall and not the piston itself

4/ Are there tolerances that poor that it requires a specific piston to be chosen to match its liner and if so that implies that a replacement piston ring may not actually fit properly making all, of the above pointless.

5/ Other manufacturers can supply a piston

ASID where are you when I need you..your good with Italian

[raptorheli2]

i understand it-basically it means screw you, your paying for more than you need.

i wasn't aware you couldn't buy spares for novarossi engines like this, just removed them from the buying list period for me.

cheers