6ril

So, I'm still not making the new top-end step ! After a little more investigation I found out that my new spark-plug it toasted. Seems that's what stopped my engine, and it's now the second spark-plug that gets toasted. Plus, I got the oil leaking out the engine (by the exhaust). It makes me feel that I'm in this situation (something I read online) : the problem : I found myself with this issue: spark-plugs are getting toasted ( 125 type185 bul) I've change the "ruptor" and got a brand new condensator, sparkplugs are still getting toasted I also have oil leaking out the exhaust making a mess all around ! could there be a link between those two problems ? an answer : For your toasted spark-plug problem, it's the seal between the 2 halves of the transmission carter that needs to be redone. I have the exact same troubles with my 185. Don't look at the ignition any longer, it's the transmission oil that goes up the cylinder: As a result, you run with an overdosed mix, and spark-plugs do not like that, and the oil oozes out the exhaust. I've resealed with a brand new seal and loctite AJ45, ans since, no more traces of oil nor toasted sparkplugs.

this video was done BEFORE it went bhooooooboooooo stop. it was for the sound of the engine

Well it was nice for a short time... I tried to go for a little ride, and 2min in, the engine went "boooooh booooohbbooooo".. stop. I pushed it back toward home, then it was downhill so I tried to start it going down the hill and it did start, but worked for less then 20 seconds. Same booohboooo stop. I got the feeling that it might seal while it's cold, but then when the engine start to heat up, dilatation appear and It loose its seal, leak and loose compression. Could it be ? What do you reckon ? I'm going the stop messing around and get a re-bore and new piston. (i keep saying it, got to do it...)

Hi everyone, I got a tip on a french forum, a forum about old tractors "pour a little oil by the spark plug hole, kick a little, put the sparkplug back and try again" I did just that. It gave some sealing I guess, the compression got better and the engine just started ! I'm still considering changing the top end, but I'll try it a little as such, if it's not too risky. What do you all think ? I'll post another video to try to get you to hear the engine without all the rattling.

hey Christian, the only test I made was to insert a piston ring inside the cylinder, and I could see the light one a section of the ring, not good, but the mechanic I was with (the one who hone the cylinder for me) told me to try anyway. I'm going to change the top end as you said, you really got me with "so much peppier" ! thanks again for the feed back mate ! Cyril.

Hi vintagenut, thank you very much for your post ! I'm going to recheck everything, and specially that woodruff key. I think I'll change it. If I still get nothing out of the engine, I'm going to try to change the piston and its joints, plus re-bore the cylinder to that new piston size. Here is a quick rough video (couldn't film everything, like the light sanding of the piston or the inside of the flywheel)

Hey Christian ! Thank you for your helpful post. I'm taking note of the shavings cleaning method You're right about the woodruff key, it was dislodged. I put it back, and it was really easy to slip it in : Is that a normal ? I'm glad you enjoyed the videos I'll post a new one soon where I put the engine back on, after having done honing on the cylinder and some light sanding on the piston : result : no compression. I guess it might be a few things : bad piston rings / bad sealing of the flywheel carter ?? dunno will seek online help first then probably pro help. Will post the video next week... going away for the week-end now. Hey Lorenzo, I agree with you, paying a pro might be the sensible thing to do. Unfortunately, I'm not rich, and if I can do it myself and learn through the process, I will try. I'm a quick learner, and I've always been self-taught on many different fields, I LOVE learning : / That said, I'm still seeking help from kind nearby mechanics you are willing to share and help. Thanks to internet and forums. Anyway, I'll keep posting what happen, and hope you'll still give me your helpful feedback. Cheers !

Hey Retromlc, thanks for the post nah... UK still have private properties in the country-side, right? Where you can still have a reasonable range of good sense freedom to ride.

OH ok, thanks for the tip Bullylover !

Found the culprit of the nasty noise in the engine.

thanks for that info Misscrabstick ! So adding gaskets would add or remove power ? the thicker the joint, the bigger the exploding chamber, right ? But for the same amount of fuel, so ... help me there

Hey, just thought I'd share this little video I made after repairing this cool Cota 25.

here, a few close ups of the piston and cylinder. It's probably hard to judge with photos but...

hey Jonboy, Lorenzo, it's definitely the lens distortion (gopro). For the multiple gaskets, there's actually 3 of them ! One went up stuck to the cylinder. There should one be 1, right ? One good one.

Hey Misscrabstick, pschrauber, thank you both for the feedback ! Wahoo I was really not aware that the piston was done. I'm going to have a proper look at it again, with your comments in mind. Got to learn a lot ! Now I know I can't do almost any of it myself, I'll have to seek (paid) help from a proper mechanic. Dam what an idot ! I did f#$% that beauty straight from the get go ! Congrats Cyril : / thanks again !