black oil out of the exhaust

[comanacu]

hello,
when i bought the motorcycle, it consumed a lot of gasoline.
i found here on the forum what i need to change in the carburetor so it doesn't consume so much.
i bought original JET-PILOT,#45 and JET-MAIN,#155

this winter i changed the piston and all the gaskets, but the problem persists. i don't know if before i changed the parts in the carburetor if it was the same,

the problem is that it spits out a lot of black oil on the muffler.
i'm attaching a picture.
the motorcycle starts perfectly both hot and cold.
i don't know what else to do.
thanks in advance.

[comanacu]

[Chuck78]

While a slight bit of black oil spooge out the exhaust is normal, especially if not running it in the power band and running it hard frequently, what you show in that picture is extremely excessive!

I would say your jetting is most likely off and/or perhaps you need to run a lower flash point premix oil.

If the bike has a pretty fair amount of hours on it, you may have a worn out needle jet in the carburetor, which is not generally available as a replacement part aside from a forum member who had some custom made. This will make it always a bit rich at low throttle openings, and is becoming more and more of a problem as these carburetors age, with usage.

Repacking the silencer would help a bit in the short term, but I would say that's not the entire problem at all, there is definitely something else going on.


Does your bike consume gearbox oil, does the level stay the same after extensive riding?

How is the compression, have you done a proper compression test on it? Is there a fair bit of resistance on the kick start lever, indicating good compression?

If the spark is weak or somehow the voltage output dropped in your ignition system, the timing would change which can also affect the ability to have a complete burn and proper timing.

[SpruceItUp]

What oil are you running and what ratio? I run motul 710 in my 92 and it has been great. Low flashpoint oils are what you will want for this bike. Also, run it at 32:1. And make sure your jetting is set for that as well. How's it run? Does it 'clog up' a lot? Are you fouling plugs?
Chuck makes a good point with the worn out needle jet orifice, that happens with use with PWK35s.
What does your exhaust smell like? If it's burning gearbox oil (actual gearbox oil) it will smell pretty foul. If it's something like rotella or the sorts it will smell like burning motor oil like Chuck said.

[ss109]

A lot of things can be causing that issue. First, have you repacked the silencer? Is your carb float set to 18mm? Have you followed the jetting guide (viewtopic.php?t=1156)? Your jetting seems really pretty rich unless at sea level. I'm running a 38pj, 152 main, CEK needle, Lucas @ 40:1, 2000ft asl. Carb could also just be worn out. Also, have you done a leak down test? A crank seal could be leaking and sucking in transmission oil.

[comanacu]

i have the bike for 2 years.
JET-PILOT,#45 and JET-MAIN,#155 i found this setings here on forum, but i dont know where, but since then the bike consumes moore less fuel, and works great

is not gear oil, becouse last sumer, my kid ride it alot, and in autum when we change the gear oil, 0.7 liters comes out of it

i had Repack the silencer and nothing

we have new piston with rings dont remember now the producer, but was not cheep

all last sumer the bike run on only one spark plug

i try diferent producers of spark plugs: ngk/bosch/denso ...

premix oil i try more than 4 producers :motul 710 2t , fuchs , castrol, even stihl (kid ran out of fuel one time in the forest, all i had was some fuel for my chainsaw)

i use 22-25:1 premix

it doesnt clog up, even if u ride it on low RPMs (i try that, im no good biker)

i wil try to folow all the jetting guid (thx for that) i only wached some youtube videos on that.

i dont see nothing wrong with the needle jet , in my opinion, ill try too check again

if iremember anything else, ill write it here