Are there any major problems with these 3 motorcycle ENGINES??

An problems with the ENGINES harley, honda, and moto guzzi are the engines good like do they last long etc

Each manufacturer has it's own quirks, but the best way to keep an engine running well is proper maintenance. Guzzi's are sensitive to valve adjustments, Harleys are blamed for leaking, however, any harley that leaks and is newer than 1984, has a problem. They used to have an adjustment screw to"control"a drip onto the chain. Most Hondas are great, there are some motors that are better than others, the early V4's used to twist the crankcases.....the list goes on for every manufacturer, so again, the best engine is the one that's maintained properly.