K&B guess
 

I have a nice running K&B motor. The motor has no markings except at the base MD. I have asked some other hobbiest and no one can be sure. Can I measure the piston to find out? If you can give me some sizes or something. The head has four screws holding it on. thanks Bodyman

K&B guess
 

Sounds like you have a K&B Sportster. They made them in four sizes ,20, 28 ,45, & 65. They have the size stamped on edge of right mounting lug. Usually a letter followed by the size ,about the only way to tell a 20 from a 28. The 45 is much larger & the 65 is really a big bugger. I have always used a fuel with 20% or better oil content (1/2 castor) & have not had any trouble with them . Running a 28 in a Sig Kadet Seniorita that has been run for over ten years with several gallons of fuel through it. MAX H.