Smoke and Oil shooting out exhaust

[captnmustache]

This is kind of a long one. Sorry. Bike in question is a '74 TX650.

I recently went on a 5 day ride with my bike. On the 2nd to last day of the ride I started running on one cylinder. We checked the plugs and they were a mess. We also switched the plug wires around from the coils to see if it was an ignition problem but it didn't seem to be. After looking at the points it appeared that one of them was not sparking causing me to run on just the one cylinder. We toyed with it for a while, filed them down and went for a ride. It seemed to be running a bit better but didn't have any lower end.

Anyways I now have the bike back home after riding it 180 miles thru Mexico on one cylinder. I have rebuilt both carbs and replaced both points and plugs now. It starts first kick however I now have smoke coming out of the right side exhaust pipe (cylinder that went down) and when I put my hand in front of that pipe it get's covered in oil.

I'm kind of lost on this one right now. Any help would be greatly appreciated.

Thanks in advance.

 

[xjwmx]

Do you have two petcocks and if so did you turn the one to the bad cyl off? If not, it might have gotten washed down with gas over that 180 mi. causing a lot of ring and cyl wall wear. Is the plug oily? Have you checked compression in that cyl?

 

[captnmustache]

I only have one petcock. The plugs were oily when I pulled them out. I put new one's in the other day. I let it idle today for about 5 minutes. Other then the threads being oily I didn't notice anything. I'll check the compression. Thanks for the help.

 

[gggGary]

Miles on the engine, work done to it? Stock air boxes? I ask that because... And this is just free thinking, blown or cracked valve seal? So if you have oil on both plugs it could be from just one cylinder or it could be excessive blow by pumping oil into the air box. with a two part compression tester you can bring one side up on TDC in gear. turn your air setting all the way down, plug your air hose into the compression tester/plug hole, gradually increase the air pressure and listen to where it's going. Weren't you looking for a rotor in Sillyfornia last week? A weak battery (charging system) can take you down to one cylinder also.

 

[xjwmx]

This is also free thinking but if your plug is dry and you have oil coming out the exhaust, doesn't the oil have to be coming down the exhaust valve stem?

 

[awoz87]

i had this issue when i bought my xs650, it ended up being a bad exhaust valve seal. i also agree with the gas washing down the cylinder wall and wearing it out though.

 

[650Skull]

Do you have a 73TX 650 or 74TXA650 a very big difference if you have to go into the motor.

Asked you the same question last year and you still have a 74TX 650 ???

 

[gggGary]

A holed piston on points bikes is not rare. Advanced timing is often felt to be the cause. There were recently pictures showing how too much clearance between the advance weights and the cam slot can allow excessively advance timing. Timing should be set at full advance (check both sides) let idle fall where it may. And casting around for ideas, maybe some of your gas was low enough octane to cause detonation?

 

[captnmustache]

The bike is a 1974 TX650A. Noticed that I forgot to mention that when I was riding back on the one cylinder that about the last 40 miles or so their appeared to be oil running down the exterior of the exhaust on the right cylinder. It could be a bad valve or seal. (not sure how that slipped my mind)

As far as the air box goes I do not have one. I have the stock Mikuni carbs with screens over the inlet. No air box at all. Motor is completely stock as are the coils.