piston ring failur

jarno · Post by **jarno** » Thu Jul 12, 2012 3:33 pm

Hello

just rebuild my engine with new cilinders and new pistons ( mitaka's).

it did run for 2 minuts and than seized.

what happened pistonring snapped how is this possible?

does anyone has had the same problems ?

regards jarno

Luders · Post by **Luders** » Thu Jul 12, 2012 3:52 pm

That sounds odd, which ring was it that snapped?

Howie · Post by **Howie** » Thu Jul 12, 2012 3:56 pm

Thats got to be a fault in the ring

I've never known an engine to seize in that short time!

However I am assuming you coated pistons & rings with two stroke oil before fitting the cylinders?

Are you running an oil pump or premix?

Luders · Post by **Luders** » Thu Jul 12, 2012 4:00 pm

It's more likely a miss located ring that caused it Howie. I've used Mitaka's before and have no complaints.

You didn't start revving the knackers off it straight away did you?

I always put my fresh engines through 3 heat cycles at idle and then make sure they are fully up to temperature before thinking about touching the throttle.

jarno · Post by **jarno** » Thu Jul 12, 2012 4:03 pm

Yes i have mounted the pistons and cilinders with 2 stroke oil.
it is running on premix

it is the right cilinder, but i must say that i can't be 100% sure that it is the ring the piston is blocking the exhaust poort ( i can see some deformd metal so i am asuming it is a pistonring).

this sunday i will open the engine and look beter because at this moment i must go to my work.

if i know the problem i will put some pics on here

regards jarno

Howie · Post by **Howie** » Thu Jul 12, 2012 4:10 pm

It's more likely a miss located ring that caused it Howie

Quite possibly Luders, I've used Mitaka's before without any probs. But from what Jarno has just posted it may be something a little more sinister.

Lets just hope its nothing too bad.

Howie · Post by **Howie** » Thu Jul 12, 2012 4:17 pm

Having a think about it Jarno, what gudgeon pin circlips did you use?

If I remember rightly, Mitaka kits come with the 'G' shaped clip, I was once advised to bin the 'G' shaped clip & use the 'C' shaped clips instead, is it possible one of these has popped out?

jarno · Post by **jarno** » Thu Jul 12, 2012 4:23 pm

Hello Howie

i have built the pistons with original circlips the have the c form.

jarno

Rocket · Post by **Rocket** » Thu Jul 12, 2012 5:41 pm

are pistons in correct way round otherwise ring will pop into a port and snag, got a motor off somebody once and this had happened, only way to get barrel off was to pull ring through exhaust port with pliers to release piston.

buzinc · Post by **buzinc** » Thu Jul 12, 2012 5:58 pm

Could be port chamfer. I had to send a cylinder back to Lancourts after they had done a replate and left the exhaust port with no chamfer!

buz

JanBros · Post by **JanBros** » Thu Jul 12, 2012 10:38 pm

buzinc wrote:Could be port chamfer. I had to send a cylinder back to Lancourts after they had done a replate and left the exhaust port with no chamfer!

buz

my bet to.

Did you check your squish ? how much was it ?

jarno · Post by **jarno** » Mon Jul 16, 2012 9:06 pm

Hello

just opened the topend and just what i thought circlip came out

new cilinder and piston and now it is running sweet $\:D/$ $\:D/$

JanBros · Post by **JanBros** » Mon Jul 16, 2012 11:08 pm

did you put in new ones the first time, or re-used old ones ?

jarno · Post by **jarno** » Tue Jul 17, 2012 2:59 pm

Hello Jan

i put new ones in but the were the originals for the mitaka's not original kwak.

now i have put original pistons in the engine.

jarno