Left cylinder still wet and oily

[RDDave]

After all I have done, the left plug on my RD350 is still wet and oily. It is better but isn't right. The right looks real good.

Is it even possible that the left could pick up oil from the transmission? I am out of ideas what else it could be........again.

[85RZwade]

It's possible; it would have to pull oil through the mating surfaces of the case. A leak test oughtta show it.

[RDDave]

That possibility is all I can think of after all I have done to track this down.

How would I go about a leak test on that cylinder?

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[m in sc]

very very very unlikely.  back to the ignition

[quocle603]

If it was the right, then definitely. Sounds like timing/spark might be off. Definitely check that all before jumping into jetting. Been there too many times before.

[85RZwade]

How would I go about a leak test on that cylinder?

.

The usual vacuum/pressure test of a two-stroke cylinder as described elsewhere on this forum. And as Mark pointed out, it's not likely in this situation, just possible.

[m in sc]

only way it would be if it was leaking thru the case. if it was coming through the crank then it would share the same issue left/right. (since the lab seal isn't air tight in the crank anyway)

check the coil. recently we went thru a bad sv coil, (probably due to it being left on too long w out running and cooking it). Resistance from the plug lead w the cap off to the terminals  was around 18k ohms as 'ok', 8-9 k was bad. 

[RDDave]

Yeah, I have switched a pair of the new Suzuki style coils back and forth along with their wires and plug heads more than once.

This problem preceded my ownership of this bike and is why it has been passed around.


I am out of ideas and feel that I have done EVERYTHING I can think of that is unique to that cylinder, including using everything from the right on it. I have a couple more things to try tomorrow.

Thanks guys, I really appreciate your patience with me on this.

.

[350GUY]

I bet the issue lies within your ignition system. Your symptoms are of incomplete combustion within your LH side cylinder in conjunction with your pilot circuit of your carb. There are many factors that can contribute to this condition, one of them being dwell, improper or worn horseshoe arm of the CB point, worn cam, type of plug cap etc....also check to see if there is any leakage via the LH side cylinder head plug hole. A hairline crack on the threads can cause mild leakage/compression drop.

[RustyRD]

 double check your ground for the coil on that cylinder, also connections to the coil all the way back to battery source. does not take much resistance to reduce amperage available for the coil. Use a multi meter to check, be patient and thorough. It is the cumulative combination of multiple connections that can really reduce current draw to a component.

[m in sc]

you dont need to ground a coil like that just fyi. not on a points system.

what was the charging voltage? its either the harness or the charging system.

[Striker1423]

Agree with Mark here.

[SoCal250]

I bet the issue lies within your ignition system. Your symptoms are of incomplete combustion within your LH side cylinder in conjunction with your pilot circuit of your carb. There are many factors that can contribute to this condition, one of them being dwell, improper or worn horseshoe arm of the CB point, worn cam, type of plug cap etc....also check to see if there is any leakage via the LH side cylinder head plug hole. A hairline crack on the threads can cause mild leakage/compression drop.

Not likely to be the points cam since that would affect both sides. He's already ruled out the points and caps since those have been swapped several times and the issue remains on the left.

[RDDave]

I have the coil's positive on a relay direct from the battery. It has 12+v. (The bike runs the same with the lights on or with them off.) And I just disconnected the harness from the points for the left cylinder and jumpered direct from the points to the coil.....again.

Remember that this is after I have swapped the coils along with their wires and heads side to side more than once.

I also went ahead and drained the gear case and refilled with 2 stroke engine oil. I also put a new Iridium plug in the left cylinder.

The left cylinder runs now. I pulled the plug; it looks better, not as soaked, but still wet around the rim. So, I checked the resistance on the points wire to the coil and since it was negligible, I removed the jumper and reconnected the harness wire. Then took it for a 10 minute ride.

The left cylinder still runs good but the plug is still a bit wet around the rim like it was with the harness out of the picture. The right cylinder has a very good, clean burn.

I am going to do a few adjustments to the carbs and ride it some more. The left plug looks much better now that it did. Not soaked and fouled, just wet around the rim.

I guess I better hope it isn't the engine oil in the crank case that is what is impacting the burn.

[m in sc]

who split the cases last? I've seen 1 or 2 cases in many decades of either the wrong sealant or a gouge allowing a leak. the BEST way I have found, is to use some fuel scent (cheap on amazon) and add it to the transfer pil. I prefer strawberry but grape is potent.  IF  the exhaust suddenly smells like that, you have ab incursion. also.. what is the charging g voltage? I don't care what the battery tests at statically. yes, it matters.