[aram]

What do you guys think about this plug? They both look exactly the same, but I'm not completely sure if this means I'm running lean or rich. Thanks for any help.

 

[Rob Axel]

First you have to identify what all that black crap is.. if it is slimy .. most likely oil. If it is dry soot.. your rich with fuel..
it looks "sooty" from the pic..
Clean them, re install.. see how long (time) it takes to get back to black.. is it while riding ? Or just sitting and running?

 

[Flyin900]

If you have done a decent longer ride of 50 miles of more and that is soot not oil then you are too rich. With modern gas containing 10% ethanol these days if anything the bike will tend to run slightly leaner with this blended gas mix.
What if anything have you done to the bike in regards to recent work and how does the bike run overall through the full RPM range?
More details on your bike model and the recent work done as some background info can help in the diagnosis. The plug colour indicates the bike is running rich unless you have had it idling recently before pulling that plug.

 

[BrianHull]

Quick assessment. Looks too rich. You got too much fuel. Perhaps a float needle failure. What's the bike doing?

 

[aram]

First you have to identify what all that black crap is.. if it is slimy .. most likely oil. If it is dry soot.. your rich with fuel..
it looks "sooty" from the pic..
Clean them, re install.. see how long (time) it takes to get back to black.. is it while riding ? Or just sitting and running?

So i cleaned and reinstalled them and went for a two minute ride and i started running on one cylinder again because i think it got dry soot again really quickly.
right is right cylinder, left is left cylinder

 

[aram]

If you have done a decent longer ride of 50 miles of more and that is soot not oil then you are too rich. With modern gas containing 10% ethanol these days if anything the bike will tend to run slightly leaner with this blended gas mix.
What if anything have you done to the bike in regards to recent work and how does the bike run overall through the full RPM range?
More details on your bike model and the recent work done as some background info can help in the diagnosis. The plug colour indicates the bike is running rich unless you have had it idling recently before pulling that plug.

I've rebuilt the carbs, new pamco ignition, new coils, plugs were recently replaced, brand new battery.
I just went on 2 minute ride and it started running on one cylinder again in think because the plug got dunked up again.

 

[aram]

Update: After cleaning the plugs again and tinkering with mixture screw and idol screw, she's back on two cylinders. I am going to check the plugs later today to check how fouled the plugs got on a 20 minute ride.

another update coming soon

 

[Rob Axel]

DO yourself a favor.. check the float bowl levels... I (untill recently) would POO-POO the whole "float bowl level" thing because I REALY didn't understand it... until my S-90 would fall on its face when WOT.. basically starving for fuel.. (after carb rebuild).. brought the float level up and she goes like hell... well, as only a S-90 can..
But with running duel carbs.. they have to be together" and feed fuel as balanced as possible so one cylinder doesn't work harder or become parasitic drag on the other..
As I have said before.. I am constantly learning more and more here.. so I'm just passing on my newly aquired knowledge as it has assisted me in getting these bikes "dialed in"..

 

[dylan dog]

HEllo
not to open a new tread........81 cm400t vb31 carbs put 118 instead od original 110 sec jet
having similar issue, one of the plugs looks identical fouled dry soot (right cyl - throtle hand side), the left little better but still not as should be (tan brown)..the day before yesterday went on a 200+ km ride on highway and it ran so well i couldn't believe it, but on arrival when checked plugs for curiosity, were all dry soot; prior to that ride, replaced the plugs with new ones! Carbs cleaned few days ago and you can tell the difference in power and response from before..
so I messed with idle screws yesterday after riding a bit (working temp) as thought it was too rich so wanted to make it a bit leaner, were 2-2,5 out the day before..now, seated, turned 1,5 out from seated, and when i make it leaner from there it doesn't idle like before,
lower throttle response, slower return on idle rpm, sputters or backfires!?(dont know the term sorry ...so if I increase the rpms, running it richer and better I suppose, I guess will have fouled plugs again..didn't check but will do that..so what am I supposed to do, as it seems cannot make it in the middle..