Cleaning the chamber and tail pipe?

[Tillerman6]

Well this old bike is still giving me surprises and while I'm waiting on the cylinder re-bore and new piston,  I thought I should look at how much crud was hiding in the tail pipe.  Not to be disappointed, the tail pipe decided to cough up a couple of peanut sized chunks of pure carbon.  So I know there is more in there somewhere.  took off the expansion chamber too of course and it was not as bad ( I think) but the engine (when it was together) would belch 2 stroke smoke from all angles when it first started up.  Could be that this carbon was what was causing the detonation during deceleration?  Something was definitely going on in the cylinder. (see pictures below)

And now the packing that resides in the tail pipe is completely soaked with dirty goo.  So I think the engine was not breathing properly when i ran it last.  I did not get a heads up from the previous owner or understand that this tail pipe cleanup was even needed.  Never had a TY before.  I'm running Amsoil Saber at about 40 to 1 which is probably too much oil.

So is this packing material really just fiberglass? 

 

[shakennstirred]

50:1 would be better

[Tillerman6]

shakenstirred,

  I am thinking you are right. About 50 :1. The break in procedure might be a little richer than that, but the Amsoil Saber does not burn completely in the engine because it has a higher flashpoint.  I have no idea what oil was used by the previous owner and I have run the bike on Amsoil Saber since I've had it, Sometimes richer and sometimes leaner, but I noticed that the piston slap was a little louder with the 80:1 which I tried briefly.  I was trying to save having to teardown the engine for a new piston for as long as possible, but the recent detonation/ banging changed my way of thinking.

I am also going to stop using engine braking as a means of slowing down on long downhills.  It just wipes all the oil off the cylinder and piston. And it still tries to fire about every 30 feet at least once or twice with a loud bang.  That was the only time I heard any banging/detonation anyway was going downhill with the throttle closed.

 

It's kind of ironic about the closed throttle position causing this problem because the engine will not start with an open throttle.  The closed position is also the recommended position for starting!

I am thinking that the carb slide must be a tiny bit open even if there is slack in the throttle cable.

I also took the oil pump off the engine shortly after i got it because having an oil pump failure would be the end of the road for this engine and I only have one.

[oni nou]

31 minutes ago, Tillerman6 said:

shakenstirred,

  I am thinking you are right. About 50 :1. The break in procedure might be a little richer than that, but the Amsoil Saber does not burn completely in the engine because it has a higher flashpoint.  I have no idea what oil was used by the previous owner and I have run the bike on Amsoil Saber since I've had it, Sometimes richer and sometimes leaner, but I noticed that the piston slap was a little louder with the 80:1 which I tried briefly.  I was trying to save having to teardown the engine for a new piston for as long as possible, but the recent detonation/ banging changed my way of thinking.

I am also going to stop using engine braking as a means of slowing down on long downhills.  It just wipes all the oil off the cylinder and piston. And it still tries to fire about every 30 feet at least once or twice with a loud bang.  That was the only time I heard any banging/detonation anyway was going downhill with the throttle closed.

 

It's kind of ironic about the closed throttle position causing this problem because the engine will not start with an open throttle.  The closed position is also the recommended position for starting!

I am thinking that the carb slide must be a tiny bit open even if there is slack in the throttle cable.

I also took the oil pump off the engine shortly after i got it because having an oil pump failure would be the end of the road for this engine and I only have one.

When you run it in you would be better off with a semi synthetic oil[there is no need for more oil than 50:1 when doing so] also the throttle slide is normally set open a little so that the bike will idle fast enough and not stall[it is set by the idle screw on the side of the carb.

It is common knowledge that you must open the throttle regularly to lubricate the cylinder and piston on a 2 stroke engine if using the motor as a brake. 

[Tillerman6]

11 minutes ago, oni nou said:

When you run it in you would be better off with a semi synthetic oil[there is no need for more oil than 50:1 when doing so] also the throttle slide is normally set open a little so that the bike will idle fast enough and not stall[it is set by the idle screw on the side of the carb.

It is common knowledge that you must open the throttle regularly to lubricate the cylinder and piston on a 2 stroke engine if using the motor as a brake. 

Oni nou,

  Thanks for that.  I have been abusing the engine no doubt. Probably picked up bad habits from running 4 strokes back in the day.  The engine braking is smoother and less likely to dump you on your head, but it is harder on the engine for sure.