Two Stroke wont start.

[Rustydog2010]

Problem is this...what happens if after a rebuild you discover that the problem still exists?
The time to solve it is NOW!!!
Something very basic is plaguing the engine.

Dont know what the problem was. It started with the exhaust of.. but then while it was still warm I put the exhaust back on and it started. I let it cool and it starts? Its a PITA to start, but it does.

Thanks for the help, I guess. Still cant figure out what was wrong with it?

Jeremy.

 

[bighead]

Sounds like your pipe is full of crap. Is there a chance it is clogged up? Does it have a silencer tip?

I had some old three wheeler pipes I had to bake in a camp fire to get the crap out. It burned flames out the pipe for about 30 minutes. I had a few moped pipes that needed the same as well.

Perhaps when you modified the pipe you broke a bunch of carbon lose. it is not clogging the pipe. Just a thought.

A little spendy but look here.

http://cgi.ebay.com/ebaymotors/1976...7916131QQptZMotorcyclesQ5fPartsQ5fAccessories

 

[Rustydog2010]

The pipe is almost impossible to clog as it is about 35mm pipe, at the narrowest part. When I took it off yesterday, a very minimal amount came out.

I would love to get a pipe like that, but these bikes don't seem to popular over here. I cant find any parts for them.

Jeremy.

 

[Rustydog2010]

Okay figured why we have low compression.






Blow-by much? Not sure if the rings have worn enough to jump off their locator pins and rotate. Or maybe it was done last time it was rebuilt.

Now it should be some fun trying to find a piston and set of rings. Anyone have any info about boring out cylinders in a lathe?

Cheers, Jeremy.

 

[sexyvicta]

i think IT yamahas have same engine as YZs like yours so if you cant find yz parts look for IT400 parts

edit: and i bet you can get new wisco pistons for it anyway if genuine are no longer available

 

[Rustydog2010]

The only problem is that, I am guessing it is a YZ the suffix's in the manual are different to that on the frame and motor.

I'll just take the numbers to my local Yamaha dealer, they must be able to give me some specs.

Jeremy.

 

[Rustydog2010]

Checked the end ring gap today and it was 15mm, about 30x the amount the manual specifies. Re-looking at the piston, it should be okay to reuse. A new set of rings will be the go.

Edit: Oh and talk about uneven ring wear, one rings maximum thickness is about 4mm and at the narowest point it is about 2mm.

Jeremy.

 

[Doc Sprocket]

15mm? WOW! That's bigger than 9/16"!

 

[devino246]

Hahaha, thats horrendous!

 

[Rustydog2010]

Okay so the rings are now made, $80NZD. Not to bad and got 3 of them.

My question for today is, having a copper head gasket should I anneal it? Or just leave it?
The only problem is, that I can only heat it in the oven as we have run out of oxygen. (You would would think having 3T's and a Q, one would have some gas )

Cheers Jeremy.

 

[Cam]

Needs to be on gas id say mate, gas stove works a treat just leave it on the element for a few minutes