Left cylinder still wet and oily

[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 trans oil. I prefer strawberry but grape is potent.  IF  the exhaust suddenly smells like that, you have an incursion. also.. what is the charging g voltage? I don't care what the battery tests at statically. yes, it matters.

2

[RDDave]

I don't know the history on this bike. It shows 5,000 miles, the cylinders were still on the stock bore with the stock rings until I threw on a set of the Chinese cylinders chasing this issue.

I have ridden the bike about an hour now and the left cylinder is still running strong. With the 2 stroke oil in the gear case, the left plug looks much better, still wet as you can see, but much better.



I like the scent test to further help define the issue. We used to use that back when we street raced our cars.

As to the charging, I can check that again. But it maintains the battery at voltage with the lights and a turn signal on. And all of my riding has been with the lights on.

I will drive the bike as much as my time allows the next few days and see how it does.

By the way, does that right plug look too lean? The main jet is stock. I have the needle raised up 1 notch because it looked a little lean to me. Everything is stock except for Bassanis.

Thanks for all the help. The bike may be far from fixed, but at least I can ride it enough to nail this down.

[m in sc]

right plug looks ok. pic below is what my 72 w the same cyls (which doesn't matter) looks like. different ignition though

[RDDave]

Rode it off and on all afternoon. In town stop and go and on the hiway at 60+.

So far, so good. I ordered some strawberry scent. It won't land until next week.

The generator puts out over 12v at idle and hits 20v by 3,000.

While I REALLY want to know for sure what the issue is and right now it looks like it's sucking gear oil on that cylinder, I don't know whether I hope the scent confirms that or not given the final fix.

Anyway, thanks AGAIN for all the help.

Is the gear case going to be happy for a while with engine oil in there rather than gear oil? I guess I could put gear oil back in and see if it starts fouling that plug again. I would rather wait for the strawberry scent. It's just a matter of how much I ride it between now and then. I would like to put some time on it to see if anything changes.

Again, thank you!

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[m in sc]

your regulator is shot if its going over 14v. the trans is specced at 10w30 or 10w40.  I run Castrol synthetic motorcycle oil in all my transmissions.  they aren't specced for gear oil.

[SoCal250]

I also went ahead and drained the gear case and refilled with 2 stroke engine oil.

Not a good idea! Two-stroke oil is not designed to be used in a transmission. Stop riding it with that oil in the trans. I would highly recommend you drain the trans immediately and refill with a proper motorcycle-spec engine oil designed for wet clutches. I use BelRay Gear Saver 75w (which is equivalent to a 10w30). There are many options out there.

The generator puts out over 12v at idle and hits 20v by 3,000.

your regulator is shot if its going over 14v.

+1, time for a new regulator. 20v is crazy high!

[RDDave]

To be honest, I think I was testing the direct output of the generator rather than the 'regulated' power. If 20+ volts were getting to the entire system, I think I would have seen some results of that by now.

The 2 stroke oil in the gear case was recommended to me by an old (very old) Yamaha mechanic who has seen this issue before. The strawberry scent will be here next week. Had I gotten that recommendation first, I would not have gone with the 2 stroke oil. But, it does seem to have had an impact. So, I will leave the 2 stroke oil in until then to test with it since it seems that the plug is not fouling with it. Adding the strawberry scent is the most definitive test.

I won't put much in the way of miles on the bike with the 2 stroke oil in the gear case. But it's starting to look like it will need to come apart anyway and I have several spare engines, so it's not that big of a deal in this case. But I appreciate the opinion just the same.

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[m in sc]

I think the old yamaha 2s or r was transmission compatible.  chuck q told me that but I don't remember which one. 

its an alternator. where were you exactly checking the voltage? what wire? it needs to be checked, running, at the  battery terminals at 2k.

[RDDave]

It was the solid red wire that is in the same bundle with the 3 white wires.

With the lights on and a turn signal on, the battery holds at 12+ volts. And I have rode it a lot with the lights on. No problems and the battery is always over 12 volts when I spot check it.

Is there something more to be concerned about given that?

And again, when I first started on this journey, the coils were only getting about 10.5 volts. I wired them directly to the battery through a relay and consequently now have over 12 volts to the coils. That additional 2 volts has not changed anything with the left cylinder.

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[m in sc]

the fact it was seeing 10.5 prior tells the the charging system has an issue or the harness as a whole is reducing voltage to an an alarming level and it hasnt been diagnosed. .

 you still haven't answered the question on what its doing at 2k at the battery & i'm not sure why.  either way approach it how you want, but its not right how it is. The non relayed power is controlled by the output of the regulator, including power tot he relay (depending how you wired it). I get powering it that way, my KZ has its dyna and coils powered trough a relay in a similar fashion.

There may be a parasitic partial short or draw at rpm you arent catching. Ive seen that before as well.   

fwiw in the tech library there is a post i made about using a ford regulator to replace the stock regulator. its an easy simple cheap upgrade/repair.

if you don't smell fuel scent in the exhaust from the trans whenever it shows up, (and i doubt you will), but if you don't, then you're right back here. If you do, then its case splitting time. even then, i still would question the charging system. you can run these for a decent amount of time on a battery, basically total loss. this can be and is common, when 1 diode out of the 3 takes a dump in the rectifier.  this would NOT be caught in your alternator output test (as an fyi). 

A dodgy electrical system is a very, very common issue with these bikes, especially at this age.  Heck, it was 20 yrs ago tbh. as has been said many times in the past: most jetting issues are electrical.   

I hope you find your smoking gun.  If NONE of that works, than something's off in the carb physically, somehow. Ive seen float level, a worn jet tube, a bad pilot jet etc cause this issue as well. 

   

[RDDave]

I will try tomorrow to run the test in the service manual for the 2,500 RPM test. The only reason I haven't went further with that is because every time I check voltage anywhere it is above 12.4 volts. With lights on or not. But, if you think something that could be amiss with that situation, I will run that test tomorrow.

I have several rectifiers and regulators so I can test run them if there is any doubt. Of course, the Ford replacement is good option, too.

And just to be clear, I have removed the bike's harness from the ignition circuit and jumpered directly to the coils. And swapped ALL ignition parts from one side to the other. Of course, that still depends on the bike's charging system.

I have also swapped a different carb on the left cylinder. The only thing I haven't done is to swap the carbs side to side.

Thank you again for not giving up on this/me. I am determined to find the cause. With your help.

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[Striker1423]

Just throwing another check if your electrical gremlin just isn't. What's your float height at in both carbs?

I had wet plugs before when the float on the left carb was set too deep for fuel.

[m in sc]

^ yup. we discussed that recently.  amazing what a mm or 2 can do

[RDDave]

My service manual says to check the voltage at the red wire coming out of the rectifier. I only have a red/white wire. The wire I checked before the battery had 13 volts at idle and 20+ by 2,500. The battery has 12.4 with the engine off, with the engine idling, with the engine at 2,000 to 3,000 for several seconds, with the lights on or with the lights off.

Those are the readings that I have always gotten. Is there something I am not testing correctly? As I said; I have other regulators and rectifiers. They just look to a bit of a pain to get at. If you think I should try other components, I will. But what other tests on what wires can I run?

I have had the carb apart several times and have even changed it out for the only other good one I had which was a right carb. But, it still ran the same. I can pull the left carb again and set the float lower.

I will be gone all day Monday. I will wait until I get the 'strawberry scent and have a chance to ruin it a bit before I do anything else at this point. If the exhaust smells of strawberries, that is all I need to know. And if it doesn't.....................

Thanks again. And I will check back on Tuesday or so.

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[m in sc]

check the voltage at the battery, when its running, at 2000 rpm.