I once had a piece of the filter cage break away and get sucked through on my 2011 so there is opportunity fior things to make it that far. Hope you get it sorted without too much cost, us the piston salvagable?

What filter cage?There is nothing in mine.The big end feels ok.I'll know better when I get the piston off.The piston is a nice ash tray now.

Had to make a wrist pin tool from a piece of pipe,washers and threaded rod,but now the piston is off.Really cool bunch of engineering has gone into the cranckcase of this engine.The big end bearing of the rod feels fine.i don't see any debris of any kind in the crankcase.I really need to build a proper workbench.

Edited January 5, 201511 yr by ric h

Yeah I just noticed 2 pieces of the cage on mine that has recently become un-attached and done the same (dissappeared), we have the motor out at the moment for a "Factory R makeover" but there are no signs of the missing plastic cage pieces in crankcase or anywhere else for that matter.

Obviously the cages dont take much knocking when re-fitting, I have fitted the 2013 removable cage/filter in my 2012 but its still difficult to do the air-cleaner, so now the bike is in a million pieces it's getting the 2013 wirring harnes to shift the ECU out of the air-cleaner.

Edited January 5, 201511 yr by digga

Yeah I just noticed 2 pieces of the cage on mine that has recently become un-attached and done the same (dissappeared), we have the motor out at the moment for a "Factory R makeover" but there are no signs of the missing plastic cage pieces in crankcase or anywhere else for that matter.

Obviously the cages dont take much knocking when re-fitting, I have fitted the 2013 removable cage/filter in my 2012 but its still difficult to do the air-cleaner, so now the bike is in a million pieces it's getting the 2013 wirring harnes to shift the ECU out of the air-cleaner.

I wish I knew what filter cage you two are talking about?

Hi ric h, sorry for hanging you out there, the 2013 bikes had the "easy change" air filter which has a plastic cage inside the foam element with a wing nut headed bolt that lets you remove the air filter/cage only.

I am guessing yours is still original (2011/12) meaning you have to remove the ECU,and relay then undo the worm drive hose clamps,remove the throttle body and then pull the whole air filter assembley out through the top of the air filter box for cleaning purposes?

Edited January 5, 201511 yr by digga

Hi ric h, sorry for hanging you out there, the 2013 bikes had the "easy change" air filter which has a plastic cage inside the foam element with a wing nut headed bolt that lets you remove the air filter/cage only.

I am guessing yours is still original (2011/12) meaning you have to remove the ECU,and relay then undo the worm drive hose clamps,remove the throttle body and then pull the whole air filter assembley out through the top of the air filter box for cleaning purposes?

Thanks Digga.My 2011 air filter is original.

Looks to me like she nipped up unless you let the filter get really dirty and it sucked dirt through but I think you would have seen that in the intake whe you cleaned the filter All the other manufacturers recommend far richer oil mix as do the oil companies I would go with them once you've rebuilt it

The intake is spotless.I'm not gonna get my panties in a bunch trying to figure out why...it's a two stroke,it happens,i'll just fix it.

Hi Ric,

Some of the early motors may have had the piston bore clearence too tight. I have worked on one that I measured at 0.0005 thou (half a thou) that had nipped up. The standard piston bore clearence is between 1 to 1.5 thou.

Also , I would not run with a 140:1 fuel/oil ratio, 100:1 is the highest that I would go to and I am pretty hesitant about using that. All my previous trials bikes I have run at 50:1.

It is possible that the motor nipped up early on in its life and has "bedded in" since then. Possible causes are the lean fuel/oil and possible tight piston bore clearence, and a lack of coolant, or non working water pump. When you get it going, from cold, have a look in the top of the radiator neck to see if there is any turbulence from water circulating. I have had a bike that from new had the water pump driving gear spinning on the shaft such that the pump never actually turned.

If you are going to re-use the old cylinder, check the piston size if it is an A or B so you can fit a correct new one, I wouldn't use the old one due to the damage and it may have warped.

Bye, PeterB.

Would you trust the average trials rider to mix fuel at 140'1?

Most are too tight to buy a decent measure and normally use an old can that doubles for the lawn mower.

I wouldn't let any of them mix me a vodka and coke let alone fuel for my Ossa.

I use a syringe from the pharmacy.Very accurate.

You can mix my fuel ,pity you're a bit far away.

Good tip though,I'll get one ,totally blows my tight Scot credentials.

130:1 with Opti-2 oil is my chosen mix. No issues at all.

sorry to sound thick but what are these ratios in ml ?