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So I keep reading some smoke from the breather tube is normal but haven't been able to figure out how much that is. So I took a video of what I'm dealing with:


Getting this after about 20-30 minutes of riding. Warm, relatively humid day (85 degress, NYC area). The bike runs fine otherwise. Not noticing a loss in power from what I can tell. Idles no problem. Dont have anything to test compression so I cant provide any details there (speaking of, anyone recommend a compression tester?).

I'm up for taking it to someone but I dont have a mechanic yet so I'm afraid if I take it in and just go "Is this normal?" I can easily just get screwed over.

Heres the bike: '76 CB360

Thanks ya'll and I just want to say how excited I am that I found this forum. Looking forward to spending some time on here.
 

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The purpose of the breather tube is to vent the gasses inside of the crankcase. These gasses are a product of combustion gasses leaking past the rings. Any engine will have some leakage. This is a basic engine heath question. Among other things, engine health is measured by a compression check.

It looks a little excessive to me. It could be caused by dirty or degraded oil. If the bike runs OK and has good power, I wouldn't worry about it.
 

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It looks a little excessive to me. It could be caused by dirty or degraded oil. If the bike runs OK and has good power, I wouldn't worry about it.
Yeah thats all I'm trying to figure out. I get what the breather tube is for I just kept seeing some people say some smoke is normal. So I just want to get an idea of what is normal.

I just checked the oil and it seems little thin to me and maybe a faint smell of gas. Hard to tell. But it was dripping all over the place cold. I remember leaving the gas on by accident overnight last week so I'm gonna change the oil tonight and see if that helps.
 

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Leaving the gas turned on does not mean gas will get into the oil. Fir it to get into the oil, the carb float valve must be leaky and the carb float bowl drain must be plugged.

How long have you owned the bike? If it is coming off a long layup, the rings maybe stuck. Riding it may loosen them up.

Be careful on the choice of oil. Modern oil with friction reducers will ruin the clutch. Most people run Diesel oil such as Shell Rotella or Chevron Delo 400. I like Delo 400 30wt. I stay away from multi grade. It has long molecule polymers that get chopped up in the transmission. The will reduce the viscosity to the lowest rating. Think food processer.
 

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Leaving the gas turned on does not mean gas will get into the oil. Fir it to get into the oil, the carb float valve must be leaky and the carb float bowl drain must be plugged.

How long have you owned the bike? If it is coming off a long layup, the rings maybe stuck. Riding it may loosen them up.

Be careful on the choice of oil. Modern oil with friction reducers will ruin the clutch. Most people run Diesel oil such as Shell Rotella or Chevron Delo 400. I like Delo 400 30wt. I stay away from multi grade. It has long molecule polymers that get chopped up in the transmission. The will reduce the viscosity to the lowest rating. Think food processer.

Just a point. You can have good floats and the drain clear. When the bike is leaned over on the side stand, it can lean far enough (depending on terrain) to cause the angled level of gas in the bowl to allow the float to open a little, allowing the gas to get above the level of the intake, but still not get to the overflow. ALWAYS close the petcock when parked.

When my 360 is parked on the stand, I get a little seepage from the bowl gasket. I lost a tank of gas over the winter because I forgot to close the petcock. I had most of it on the ground, some of it in the engine. Had to change oil before using.

Aluminum cam journals fail quickly with diluted gas, so best to keep mindful of that and close the petcock. I close it even if I am stopped for a minute or two.
 

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Just a point. You can have good floats and the drain clear. When the bike is leaned over on the side stand, it can lean far enough (depending on terrain) to cause the angled level of gas in the bowl to allow the float to open a little, allowing the gas to get above the level of the intake, but still not get to the overflow. ALWAYS close the petcock when parked.
In addition to the gasoline in the float bowls on a motorcycle that's sitting on its side-stand imitating the water in a ¾-full glass when it is tipped at an angle, lol, I'm pretty sure I read something recently about the floats not being able to function properly when the motorcycle is angled over a certain way / past a certain point. I assumed that was because the actual float would no longer be at a "straight" orientation in relation to the rest of the float mechanism, the little lever wouldn't be swinging 100% freely (lots of things tend to bind up when they get cockeyed), and suchlike. Then, again, I may have misread, misremembered, or misunderstood the post.

But I always shut my fuel petcock valve off early enough that the engine stalls due to lack of fuel. I hope, at some point in the distant future, to be able to rebuild my carburetors (et cetera). If/when I ever do... I'll still be closing the petcock before I reach the end of the ride. I don't see where it could possibly hurt anything to do so, and the practice ensures that I'll never run the battery dead because I'd shut it ("once in a great while," kind of thing) and forgot to open it before giving the starter button a tap - turning the fuel supply on is part of my regular starting sequence. (I'll probably end up flipping the kill switch by mistake at some point, though :lol: .)

Regards,
 

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I usually run the last 500 feet with the petcock closed too. Keeps the level lower in the bowl and prevents leaks....Occasionally my senile dementia gets in the way....

Three signs of getting old:

1: Random forgetfulness
2: I forget
3: I forget
 

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You only get 500' before you stall from fuel starvation? Wow... I must definitely have one carb that's completely clogged in its jets - and the other must be so near that that I'm running scary-lean on the functioning cylinder, too. I get, well, let's see... Stop at stop sign, close petcock. Ride a block, stop. Look around, turn left. Ride about three blocks including a little downhill and uphill (end up about the same elevation coming or going). Hit about 40 mph there (err, I mean 25 mph, just like the sign says). Stop, fart around walking the motorcycle back and forth until I'm facing the other direction (dead end with guardrail across the end, people parked on both sides, not enough room to circle). Look around. Head back the three blocks, trying to rev high in the first three gears so I can hit fourth gear without being too low in RPMs, which must mean I'm doing at least, err... <COUGH>25 mph, just like the sign says<COUGH> and then start slowing down. Basically, I spend as much time as I can north of 5,000 RPM as that way I can tell myself I'm helping the motorcycle by charging the battery instead of harming it by running on one cylinder and making friends left and right amongst my neighbors due to the loud exhaust. I've slowed down and stopped at the stop sign, so I look around, go straight a block (top of second, generally (NOT redline, though)). Another stop sign. Straight half a block, left into my driveway, up it and into the shed. If I haven't done something stupid like forgotten that it's wounded and has no power off-idle (whoops, stalled it) at one of the stop signs, encountered (rare) traffic, or gotten a dirty look from LEO for riding around my neighborhood with no helmet, plates, or muffled exhaust and had to go in a different direction... I still end up "high-idling" it for a minute in the shed so it'll stall.

Maybe it's time to just pull the battery and let it sit licking its wounds until next Summer when (hopefully) I've got two pennies to rub together?

Regards,
 

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Discussion Starter #9
Leaving the gas turned on does not mean gas will get into the oil. Fir it to get into the oil, the carb float valve must be leaky and the carb float bowl drain must be plugged.

How long have you owned the bike? If it is coming off a long layup, the rings maybe stuck. Riding it may loosen them up.

Be careful on the choice of oil. Modern oil with friction reducers will ruin the clutch. Most people run Diesel oil such as Shell Rotella or Chevron Delo 400. I like Delo 400 30wt. I stay away from multi grade. It has long molecule polymers that get chopped up in the transmission. The will reduce the viscosity to the lowest rating. Think food processer.
Well on top of the petcock being left open, I checked the oil level today on the center stand and the oil level was higher than the last time I checked it a couple weeks ago. Both times cold. Both times I didnt screw the dipstick in. Just rested it on the threads. It was actually slightly higher than the full line. Wondering if thats contributing to the smoke.

I've had the bike about 3-4 months now. Its in great condition and has run well. The owner before me didnt seem to ride it much but kept it in great shape. Recently had it serviced and the only way I can describe the feel of the bike when I first had it was the engine felt "tight". 4k RPMs felt like the engine was gonna explode. But since riding it its losened up a lot. The gears feel longer if that makes sense.

I've searched all over on what oil to use and saw everything from "the cheapest 10w-40" all the way up to the Shell Rotella. Synthetic vs Non Synthetic. On and on. The manual recommends high detergent 10w-30/40. I dont know how to find an oil with high detergent so I purchased this. Good?
 
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