Need to know. What is syphilis risk of a guy touching his penis with sores and then fingering you?

Possible. It depends on the characteristics of the lesions but you are surely at risk. I would recommend abstaining from sexual activity involving this gentleman until he can be treated. Always be respectful to yourself and don't ever hesitate to tell a male "No."
Syphilis. Assuming you saw the lesions on his penis, and they were syphilitic, a very rough estimate of risk of transmission is about 30-35%. The primary chancre of syphilis is most often painless and solitary, so the lesions shouldn't be called "sores." The incubation period of primary syphilis averages about 21 days. You should always practice safe sex. See your doctor, if you are concerned about an STI.
Very low risk. Duplicate question, same reply. Syphilis is rarely if ever transmited by hand-genital contact, fingering, etc. Virtually all syphilis is from vaginal, anal or oral sex. And "open lesions" of the penis aren't likely due to syphilis, and if your partner isn't gay or bi, it's unlikely he had syphilis. Multiple open lesions of penis is of concern for herpes -- also low risk, but more so than syphilis.
Low risk. but not no risk. My question is why the &[email protected]$ doesn't this guy get treated? Go get checked, simple blood test.