Sport moped exhaust on 66cc (Build thread)

[Vikingimike01]

Back. I was working on it..
So. I opened up the magneto. About a half milimeter of the pull start scraped off, so I had to clean the whole thing, it was full of metal chips. Anyways, I took off the magneto, and the seal was out 1mm. I took it out. The seal had some kind of wire... like a telephone wire, or like what showers have. It was like a coil. Anyways. It was out, i put it back inside of the seal, i hope it belongs there under the rubber. I pushed the seal back in, it went in about 1mm deep, so it's now not flush, but a bit deeper.

Okay. There's a bit of blow-by on the piston, and a thick charcoal layer on top, wich I have scraped off with a knife.

I was having problems again. It's now slightly leaking from the clutch side... Wtf? Seals again I bet.

Can someone send me a video on how to fix that ??

Edit: There was a 4mm section missing from one of the ends of the piston rings... the top one. Not sure where it went, or how it broke. I swapped it anyways.

 

[GreasyChris]

Hope the other part of the ring went out the exhaust port and not inside the engine. To replace the other seal you will have to remove the clutch cover and bevel gear. You can carefully pry the seal out with a small screw driver. Careful is the key word. The spring you found on the other seal is supposed to be there. That's what applies tension on the lip of the seal to seal it to the rotating shaft. You can probably press it back in with your fingers again being careful not to knock the lip that seals it to the shaft.

 

[Vikingimike01]

Alright, thank you. I have no idea what caused both seals to come out... I'll try to look for a video on how to replace that one. Currently it's 48 degrees celsius in the sun. I have my sun umbrella up, and have all my stuff under it, including me. 40 degrees celsius under the umbrella with a big fan blowing. Nice.

Same procedure as with the last one to fix it?

 

[GreasyChris]

Ya pretty much. With whatever water you may have had in the engine it may have caused the compression to blow the seals out

 

[Vikingimike01]

Okay, I'm back. I cleaned everything out with a toothbrush. All seals are now back in. Put it back together.

Guess what. It's impossible to pull start. It's something to do with the magneto. It's about 2x as hard to pull as it was when it worked. I have this thing with my pull start that if i dont put it on right it will just not roll. But it's possible that I put the magneto on wrong or something, or the thing around the magneto..

 

[CrazyDan]

For future reference, never ever ever pressure wash an assembled engine. It will always blow seals and gaskets... That brownish liquid is most certainly rust.

 

[Vikingimike01]

I pressure washed it from the outside, mainly the bike itself..
Anyways. Tomorrow I'll try to figure out why it's so hard to pull it!

 

[CrazyDan]

It might be that missing piece of ring .

 

[Vikingimike01]

It can turn over. But it's very hard to pull it! I'm pretty sure it's not the ring, but the magneto / pull start not installed correctly.

 

[Vikingimike01]

Guys. I found the problem. At the clutch, there's that little bevel gear, and a black screw thing is holding it. It has a long cut in it. I think I overtightened that, because I screwed it out half a turn, and it was a LOT easier to turn the wheel.

But, I still don't know how tight it should be. Like exactly. I don't have a torque wrench. If someone knows how much to turn it in exactly, like let's say turns with a screwdriver. Please tell me! Or do I do it just enough so it holds the gear?