Mustard oil in 73 Honda CL350

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Mustard oil in 73 Honda CL350

Postby Kickstart_Wizkid » Sat Mar 06, 2010 3:52 am

Hey everyone I was wondering if I could get some sage advice from some of you old-timers out there. :203
I have a 1973 Honda CL350, mileage 9500. It is old, but not used much. Here's a pic:

I drive the bike on a weekly basis. Being the cautious person I am, I do routine checks at the start of every week: oil level, tire, lights. And just like most weeks, on Monday everything checked out fine. I rode it Monday in clear weather. Tuesday I rode it and it rained. I didn't ride it Wednesday or Thursday. Friday rolls around and I take it out, and it starts up fine. Idles fine. I take it out and don't get 100yards before I lose rpm: engine sputters a will not rev when i pull the throttle. I kill it, and huff it back to the garage, where i plan on diagnosing the problem later that day.
Here is what I found:

My first guess was I just forgot how low fuel i had. Fuel however was fine and fuel flow was not obstructed (carb bowls refilled when i drained them). Next I proceed to check the timing (had been long enough to consider it had fallen out of timing). Removing the generator plate to this bike releases about a tablespoon of oil, and that is when I noticed milky-tan strains of oil coming out with the regular oil. I immediately pull the dip-stick and this is what I find:

Oil has clumped to the dip-stick, and looking inside the crank-case it is also like this on the inside. The oil is a tan color, and thick like mustard. There is still an oil level of clean oil in the case, but this stuff is in that as well. I haven't had time to drain the oil yet to measure how much comes out (and therefore how much is left as pecan-custard on the inside: It is a 2quart bike of 10W-30).

My questions are two-fold:
1. What in the hell happened to my oil? Did I get water in it? And how do i get this stuff out? I can tell by how thick it is that it won't completely drain out the bottom of the bike. And since I ran the bike, I should bet that it has found its way into the oil filter/pump, and onto the upper-parts of the engine like cams and chain. So its certainly plugging up proper oil lubrication, which (yikes!) might be why it showed resistance to revs.
After a string of curses and cooling off, I dwelled on the what I might do to clean up the engine compartments that would not entitle completely disassembling the engine:
a. I completely fill the crank-case with a solvent (like mineral spirits).
b. I cycle the engine using the kick starter, but i unplug the sparkplugs to avoid any combustion. I do this several times.
c. I drain the solvent, and add more.
d. Rinse, repeat until it starts coming out clean.
e. I then repeat the exact same thing with something slightly thicker, like a very thin 5W-** oil.
f. Rinse, repeat until oil comes out clean.
g. Replace with 10W-30, 2quarts.

Does that sound like it might work, or anything that might additionally harm?

Question 2:
2. How did this happen in the first place? So a seal or gasket is out somewhere. (The bike doesn't lose oil normally, however). Is there something I can do to identify any places water could have gotten in? Anything common? Is the low-performance i experienced directly related to the contaminated oil, or are they both effects of something else gone wrong?
The last maintenance I did to the bike was standard re-timing, but I also adjusted the tappet clearance on the valves for both left and right cylinders. I have a service manual and I was confident it was to spec, following the manual to a T.

Any advice yall can give me would be greatly appreciated.
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Re: Mustard oil in 73 Honda CL350

Postby dig » Sat Mar 06, 2010 5:50 am

It sure looks like water contamination,waat you have done so far is good,i guess new oil an run it untill its hot then drain,change oil filter refill with oil and check thing that can let water in EG the oil filler cap and any thing that looks like it will let water in. :250 :203
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Re: Mustard oil in 73 Honda CL350

Postby Tman » Sat Mar 06, 2010 9:10 am

Just use it more often, and get it hot enough to burn off the condensation in the engine oil.
Less fannying, more riding. Simples.........

{Clean bike though.....}
Last edited by Tman on Sat Mar 06, 2010 1:02 pm, edited 1 time in total.
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Re: Mustard oil in 73 Honda CL350

Postby MOUSE » Sat Mar 06, 2010 9:39 am

Agree it's condensation in oil, likely from weather humidity combined with cold/ short running the bike. New oil and filter and run so engine gets oil gets hot to burn off any water ...20 minute ride, unlikely anything to do with performance. Our Mini is bad for custard in the cap from round town running.

You said you had been riding in rain, any moisture getting into electrics or fuel? Nice clean bike , don't by chance us a hose on it, that will get things wet. Water in bowls could make bike splutter, did a clean out and fresh gas fix that? Spark Plugs checked for good spark? Timing should be o.k if it's been running o.k.
"My arthritis has gotten so bad I can hardly grip anything, my cataracts seem to get worse every day, I have gout in my right leg and can't bend my knee and I can't hear anything.
But thank God I can still ride
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Re: Mustard oil in 73 Honda CL350

Postby L.A.B. » Sat Mar 06, 2010 2:17 pm

Kickstart_Wizkid wrote:How did this happen in the first place?

Here's the answer.

Kickstart_Wizkid wrote: not used much.

Find out what is really causing the bike not to run, as the emulsified oil is unlikely to be the cause of the problem, and then go out and ride the bike far enough (and fast enough) so that the oil gets HOT. The water contamination in the oil will then begin to evaporate away.

Water mixing with the oil in cold damp winter weather (which is also commonly referred to as "mayonnaise") in an air cooled engine* is generally caused by the engine oil not getting hot enough to boil off the water contamination that results from combustion gases which get past the piston rings, and also from moisture in the air that is drawn into the crankcase through the crankcase breather.

*(in a water cooled engine it can also be a symptom of a blown head gasket, where the coolant has got into the oil by leaking across the gasket face)

I'm guessing that when you do ride the bike, that you are not going very far, maybe doing no more than about 10 miles each time?

Kickstart_Wizkid wrote:g. Replace with 10W-30, 2quarts.

Yes, it could be worth changing the oil if it really bothers you, but there's no guarantee it won't happen again during cold weather if you continue to do short journeys. I don't recommend that you try flushing the engine with any type of solvent, as that is totally unnecessary.
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Re: Mustard oil in 73 Honda CL350

Postby Kickstart_Wizkid » Wed Apr 14, 2010 3:23 am

Thanks everyone for all the advice. And yall nailed my riding style right on the head. I gave the bike a little TLC, drained the oil, replaced with new oil and spent money on an additive to make myself feel better:
With the cold weather gone (70s by day) I don't expect to see anything like before.

The sputtering I was experiencing was unrelated to any issue with the oil as you diagnosed; I pegged it a combination of poor fuel flow and a bad battery. I have had a long sour relationship with the carburetor on the left cylinder (the bike is a two cylinder with twin carbs) a
I don't have any pics handy, but the floating mechanism in the bowl doesn't appear to be the original (plastic piece). The right carb has a bright and shiny brass float that looks factory.

If I could poll the minds of everyone out there one last time:
In ye old day I assume one could have readily found replacement rubber pieces for the carburetors. What options are available to me today if I want replacement carb parts?
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Re: Mustard oil in 73 Honda CL350

Postby MOUSE » Wed Apr 14, 2010 5:32 am

Carb parts/ seal kits for this model on EBay.'

Likely a Honda dealer in your area has a box full or can source them.

Probally the trouble with a middle weight bike is they are both great around town and for short hauls on the open road.

Take the long way home, warm the motor , enjoy the ride :209
"My arthritis has gotten so bad I can hardly grip anything, my cataracts seem to get worse every day, I have gout in my right leg and can't bend my knee and I can't hear anything.
But thank God I can still ride
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Re: Mustard oil in 73 Honda CL350

Postby -zkptn- » Wed Apr 14, 2010 4:20 pm

Thats a tidy looking bike. I'd park it in my garage..

Have a look at this place for old Honda bits. I swear by them...

Have you had any results with the seafoam? It got some good feedback on the CBF forum regards sorting out intake issues but some peeps dont recommend adding it to a wet sump?

'82 CB900F....Silver and gorgeous
'84 CB750F2....My scabby rat
'80 CB900F....Ongoing track bike project
'86 NC21 track bike....Red hot V4 crotch rocket
'91 FZR 1000 (zip ties and duct tape)....Strictly one for the track
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