Hello! My Dt100 is smoking way more than usual with the autolube system. I haven't changed anything but a carb rebuild so im not sure what it could be. The plug is fouled and i cant rev high because of it, could the issue be not revving enough so the oils not being burned fully? Or is there just too much oil? is there an easy way to tell if the autolube is pumping too much?

Crank seal is the most likely suspect.

Any way to confirm that? My transmission oil is the same level it's always been at

Thanks for posting the history. It's not the oil, it's too much fuel.

Did you put a "kit" in the carb with new jets? If so, put the original jets back in.

Also if the o-ring on the "jet setter" that seals the float bowl to the needle jet is missing, wrong, or damaged it will run super rich.

No, it was the stock carb and i replaced or kept all the seals, as for the jets, stock that was in there was a 160 and i live at about 3700 feet elevation and it was running super rich to the point of not starting so i put the jets down to a 120.

First, Mark knows more than I do so follow his thoughts first. If the crank seal just started going bad, you levels would not drop yet. Is it the typical color smoke or more white than normal?

That's a huge jump on the main jet... which by the way, has nothing to do with starting. There's a Mikuni tuning manual in the tech library that might be helpful.

I'm still going to say "carb o-ring" or something wrong in the carb. Just a guess.

Hope you figure it out!

it's blue smoke. I also went from 160 to 140 then to 130 to 120 then 110 then i settled on 120 so i didnt just jump, i spent a lot of time tuning. what is the "carb o-ring"?

#3 in the following diagram. must be in good shape, flexible and not cracked, or it will leak and cause what you are describing. Lube it just a little when you put the carb together each time.
www.partzilla.com/catalog/yamaha/motorcy...75/dt100b/carburetor

last time i had it apart that was in good condition, i guess ill check on it again