NickMacro Posted May 24, 2020 Report Share Posted May 24, 2020 Can anyone tell me what piston this is?i was told it would be printed with the letter a,b,or,c on it.Really struggling to get the piston kit I need.And she’s smoking badly also spitting oil out of exhaust.....Help... Quote Link to comment Share on other sites More sharing options...
Bilko Posted May 24, 2020 Report Share Posted May 24, 2020 Should be stamped on the crown of the piston,but can't see 1 on your pics,But what ever size you fit ,the barrel will need to be re nicosealed to suit.https://www.splatshop.co.uk/montesa-cota-315r-piston.html 1 Quote Link to comment Share on other sites More sharing options...
jimmyl Posted May 24, 2020 Report Share Posted May 24, 2020 Might be stamped on the barrel - above the gearbox sprocket - seem to ring a bell. Does the bore look worn - damaged - might just need rings . If its just smoking and blowing out oil are you just putting too much into the fuel - is it sounding rough or down on power. If oil mix is ok check crank seals to make sure its not drawing oil in from there 2 Quote Link to comment Share on other sites More sharing options...
baldilocks Posted May 24, 2020 Report Share Posted May 24, 2020 Oil coming out of the exhaust has nothing to do with rings or the piston on a two stroke. Jimmy is correct its either too much oil in the petrol or the crank seals are gone. If its constantly running at very low rpm it may just need to go for a blast down the road. 2 Quote Link to comment Share on other sites More sharing options...
suzuki250 Posted May 24, 2020 Report Share Posted May 24, 2020 (edited) its hard to tell from that picture but the piston & bore look ok? take a picture with the piston all the way down Edited May 24, 2020 by suzuki250 2 Quote Link to comment Share on other sites More sharing options...
b40rt Posted May 24, 2020 Report Share Posted May 24, 2020 All of the above, check if your gearbox oil is down pointing to crank seal failure. 1 Quote Link to comment Share on other sites More sharing options...
Bilko Posted May 24, 2020 Report Share Posted May 24, 2020 Looks like a single score mark on zooming in Quote Link to comment Share on other sites More sharing options...
b40rt Posted May 24, 2020 Report Share Posted May 24, 2020 2 minutes ago, Bilko said: Looks like a single score mark on zooming in Think its dirt as its hiding the ring. Quote Link to comment Share on other sites More sharing options...
NickMacro Posted May 24, 2020 Author Report Share Posted May 24, 2020 The piston was full of black sludge when I took the barrel off.I was hoping for a quick fix? Quote Link to comment Share on other sites More sharing options...
baldilocks Posted May 24, 2020 Report Share Posted May 24, 2020 (edited) 4 hours ago, NickMacro said: The piston was full of black sludge when I took the barrel off.I was hoping for a quick fix? You may well get one not involving a new piston. Apart from smoking badly and oil coming out of the exhaust are there other symptoms ? When a new piston is required the engine will rattle at tick over. If it's not doing that then it doesn't need a piston. Things to check Is the float set correctly in the carb Has it got the right jets in the carb Is it using gear box oil How much 2t oil are you mixing with the petrol ? Edited May 24, 2020 by baldilocks 1 1 Quote Link to comment Share on other sites More sharing options...
retromlc Posted May 24, 2020 Report Share Posted May 24, 2020 Out of interest, did you remove the piston to clean the black carbon.off the top of the piston or clean it while in the barrel? Quote Link to comment Share on other sites More sharing options...
NickMacro Posted May 24, 2020 Author Report Share Posted May 24, 2020 I just gave it a wipe inside the barrel.i was just cheaking the piston size and top see if that was the problem.i cleaned it.Started it and still smoking and spitting black oil out of exhaust.Ive was trying to see what piston I needed?Still don’t know ? Quote Link to comment Share on other sites More sharing options...
b40rt Posted May 24, 2020 Report Share Posted May 24, 2020 Have you read all the suggestions and ruled them out, one by one ? Quote Link to comment Share on other sites More sharing options...
NickMacro Posted May 24, 2020 Author Report Share Posted May 24, 2020 Not yet I’m going to start tomorrow ruling them out one by one.Ive only just got the Bike a couple of weeks ago.Trying to make her run perfect 1 Quote Link to comment Share on other sites More sharing options...
retromlc Posted May 25, 2020 Report Share Posted May 25, 2020 Was it running like that when you bought it? Or has the problem developed since, if since have you mixed too much 2/ oil? Maybe if you ride it for a bit it'll clear if the exhaust is soaked in oil? If the bike sounds ok I'd run it around a bit, maybe build up throttle to see if it clears. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.