Hi there and welcome to MBc. I'm sure we will be glad to have you, but there are a few things you must do. Read the Forum Rules at the top of this page, and read all of the Stickies. They all contain valuable information you are going to need and follow to get around all of the Forums. Then, go to the 4-Stroke Forum and General Discussion Forum and read thru everything there. If no luck, open a new thread with your question in the 4-Stroke Forum...That is where it belongs. Good Luck. I'm not sure that Grubee makes a 4-Stroke engine, but that is really not my area. As for an off shore 4-Stroke, look for a Hua Sheng. My engine of choice in that area is the Subaru EH035.
Patrick