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Discussion Starter · #1 ·
ok, so I'm working on my wifes 68 cb 350. she bought it quite a while back and has rarely ridden it. Last year she wanted to ride it so I got it started for her and took it for a ride ran for a while and than died on her. I had a dead cell phone battery so she had to push it home a few blocks (not very happy at all!). I started it when she got home and it was barely running and smelled of gas. Shut it down and tore into the carbs a few days later. Found out that one had a torn diaphram so I bought a replace ment kit and mounted new diaphrams in each carb. Carbs were different slides, needles, etc. got them to the same specs and left it at that. Started but still ran bad, she didn't ride it for the rest of the year. I guess she didn't want it to die on her again and have to push. Ok, fast forward to almost a whole year later. She has the itch to ride so I get a new battery so she doesn't have to try and kick start it. Put it in and it starts after a few cranks. Still doesn't seem right so I check the spark. No spark on the left side. Said screw it and just bought up and ebay set of coils and a condensor to try on it. While I'm waiting for the different coils I wanted to try to see if I could see what the points and timing looked like. Pulled the cover off of the points and it looks pretty clean in there. Pulled the cover off of the stator and out floods about a quart of really gassy oil!! WTF, so here starts the questions.

1) there shouldn't be an oil in that area, right?
2) could the motor not firing on that side for an extended period of time build up fuel and oil there?
3) could the pressure inside of the crank case push the gassy oil past the seal and into the stator area?
4) after the new used coils come, should I fill it with oil again before i fire it up? I'm guessing yes
5) does it really matter if oil is in that area, seemed to actually run half way decent even the way it was
6) fool proof timing procedure for points opening , where do you line up the LF with? the little nub sticking out on the stator

Ok, should be enough questions to keep you guys entertained
 

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The oil being there is absolutely normal for these bikes. What is not normal is that the oil is mixed with gas. Did you leave the petcock open and flood the carbs? This can cause the oil to get fouled with fuel.
Drain the oil completely and add fresh oil. Do not run it with gas fouled oil.
For the timing procedure, refer to the factory shop manual. You need to align the LF with the little mark on the top left of the stator (at about 10 - 11 o'clock). You will need to set the points gap before you do this though. Its all there in the manual..
 

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Here's some answers to your list:
#1 - "YES" there IS supposed to be oil behind the stator cover of a 350 twin motor. The FSM (Factory Service manual) instructs you to put a 1" Wood Block under one side of the Center Stand Feet to TILT the bike when removing that cover. Once tilted there is usually just a dribble of oil that escapes. Usually while setting the timing.

#2 - "NO" not firing on one side would not cause that. The common cause is the Brass Needle and Seats that don't seal perfectly. Most modern Float Valves use a Neoprene (rubber) Tip on the Needle to insure a complete seal. "IF" you leave the Fuel Petcock "ON" Gravity will overcome the Float Valve Seal and flood the carb with the excess running down thru the cylinder past the rings into the crankcase. DO NOT RUN THAT MOTOR WITHOUT CHANGING THE OIL ! !

#3 There is no seal between the Oil Sump and that side of the Crankcase see answer #1

#4 - See BOLD in #2

#5 - That little NUB has a Line Stamped in it. Do a search for 350 Timing there are several detailed posts outlining the procedure.
The short version is:

- Set the Gap for Left Points to as close to .014 as possible (the middle of the .012 to .016 Range)
- Using a 12 volt light bulb with patch wires and alligator clips connected to the HOT side of the Left Points and Ground set Timing by rotating the breaker entire plates adjusting the timing to the point where the light just goes "ON" with the Crank at "LF" on the COMPRESSION STROKE (you can watch the values open and close if you remove the spark plug).
- Move the Light Bulb to the Right Points and the Crank to "F" Again COMPRESSION STROKE and this time Adjust the "GAP" on the Right Side Points until the Light just goes "ON".
- Check the GAP on the Right Side Points is within the .012 to .016 Range if it is your good. If Not re-adjust the gap on the Left Side and start over.
 

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Discussion Starter · #4 ·
you guys are on top of it for answering questions quick. Wish I would have known about the wood block to prop up that side. It probably wouldn't of helped me though, there was quite a bit of fuel/oil in there. Kind of pisses me off considering my wife insisted she have a friend of hers work on the bike instead of me. I can handle working on 2 stroke snowmobiles fine but she thought this was not my area. Heck, the other guy never even noticed the bad diaphram and the different carb needles, etc. I think I might have a manual around here, I've got to dig.

Oil type and weight?

Thanks a lot for all the help already!
 

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Discussion Starter · #6 ·
Thank you very much. Opinions on flushing out the gassy oil in the crank case? Would all it do is just loosen up all the junk and let them be distributed in the oil again. I think I might just leave it instead of having it getting mixed around in the new oil.
 

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Just pull the drain plug and leave a pan under it for 24 hours. It will drain enough on it's own.

Add fresh oil and you're back to normal.

The problem with the gas in the oil is it will thin the oil reducing it's ability to lubricate.
Also the oil pump is designed to move a specified viscosity of oil. Thinner oil just won't pump correctly.
 
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If the chamber vere supposed to be dry, why is the cover sealed then?
The reason of oil there is at the first that the oil transports heat away from the alternator coils, and second that it's easier to seal a cover than an axle!
 

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Armand - I believe the reason there is Oil in the Left Side Case is to lubricate the Starter Chain & One Way Clutch assembly.
 

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If the chamber vere supposed to be dry, why is the cover sealed then?
The reason of oil there is at the first that the oil transports heat away from the alternator coils, and second that it's easier to seal a cover than an axle!
The oil is also there to lubricate the moving parts of the starter....Chain, sprag clutch components/rollers, etc.....
IF heat removal were the primary concern, the cases would have signifigant finning in that area as well.... The aluminum would transfer heat more efficiently than the hot oil bath....

LOL...Yendor beat me to posting.......;)
 

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Discussion Starter · #11 ·
The old Suzuki TS 250 I had used straight 30 weight non detergent oil. The manual for the CB 350 calls for 10w30. Should this also be non detergent oil so it doesn't mess up the clutch plates?

Sent from my LG-LS696 using Tapatalk 2
 

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Regarding oil: It must specify 'Wet clutch motorcycle oil'.
20 odd years ago 'new, fancy oil' would boast that it included synthetic friction reducers.
Now, due to emission controls etc. all oils -unless they specify it- have friction reducers.
Problems is, your wet clutch won't grip that well with this 'new' type of oil. It cannot be too 'slippy'.
Hope I'm not stating the obvious. Forgive me if I am. No intention to insult your intelligence.
 

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Detergent oil is specified. My CB360 (similar oil system, same oil filter) calls for it.

Detergent oil removes deposits, so they get delivered to the filter and get removed. Non detergent oil will cause deposits to stay in place, building up, and eventually bocking passages.

2 cycle engine is a different animal. It has a separate oil system for the gears. No oil pump. Non pressurized oiling systems need the oil to be a little more clingy, and depsits in that case, actually help retain oil in place.

Even Briggs and Stratton lawn mowers use detergent oil nowadays. They are still flat head (side valve) motors on most of them, splash lube.

Unless the company specifically states non-detergent, stick with detergent oil.
 

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Discussion Starter · #14 ·
Ok so I picked up some standard old 10w30 oil, nothing fancy. Should I not use this?? I don't think it says anything on it about wet clutches. Amsoil Synthetic 10w30 for motor cycles was the other stuff I almost bought and it did mention transmissions on the front of the bottle. I want to make sure I have the right stuff before I pour it in.

At least I figured out why I had so much fuel in the crank case. The paper thin Brass float bowl had a tiny crack in it. The only way I found it was to take the bowl off the carb, shook it and heard some sloshing in it. It must have been holding the needle open by hanging down with the fuel in it. Luckily I had a spare parts carb that I could take the bowl off of to use on the bike.
 

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The oil is also there to lubricate the moving parts of the starter....Chain, sprag clutch components/rollers, etc.....
IF heat removal were the primary concern, the cases would have signifigant finning in that area as well.... The aluminum would transfer heat more efficiently than the hot oil bath....

LOL...Yendor beat me to posting.......;)
Ofcourse it lubes the parts wich is situated inside too!
But fluid-cooling IS superior to air-cooling. In this case especially because the cooling fluid are in direct contact with the parts wich build up heat!
 

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Oil only gets cooled from the air. There is not much oil on the alternator because the spinning rotor would drag and foam the oil. The upper part of the stator sees little to no oil.

On these bikes, oil doesn't cool the alternator much at at all.

You are mistaken again. More modern bikes have oil/air cooled and have oil coolers. These older bikes have no oil cooler. I suspect you are not familiar with the 60-70's era motorcycles



Sent from planet Earth using mysterious electronic devices and Tapatalk
 

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If the chamber vere supposed to be dry, why is the cover sealed then?
The reason of oil there is at the first that the oil transports heat away from the alternator coils, and second that it's easier to seal a cover than an axle!
who said the chamber was supposed to be dry?...it's not..

Oil mist/splash finds it's way to this area from the left crank bearing, there are oil drain passages that allow any accumulation to drain back into the sump.
it was very common in this era to lubricate ancillary components from oil mist/splash rather than directly. there is not much oil circulation and certainly not enough to provide any cooling

on the race bikes we run crank fired CDI ignitions with no starter...we install different side case covers that have oil seals on the crank shaft and seal the return galleries.
 

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The reason that the oil is cooled is to maintain its lubrication and viscosity. Yes there is a slight cooling with respect to the internal parts, but certainly not the alternator windings. On a modern liquid cooled bike water in the main vector for cooling as its heat carrying properties are far superior to oil. Water requires 1 calorie /ml of 4.18 joules.

The specific heat of oil 1.67 kJ/kg.Kg
The specific heat of water 4.19kJ/kg. 2.5 times greater than oil.
 
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