I talked with a service person about McCULLOCK engines. They do not have any parts blow -up views or manuals for the MB290. If you need a engine part...it looks like you have to get entire engine!!! I also talked about the 50cc chain SAW engine. He said the engines seem to be very good with hardly any problems. But the saw itself has many problems with plastic parts breaking and other non engine related faults. Looks like to me there will be a good chance to buy a 50cc engine for a reduced price. May be a good engine for RC? Has anyone coverted the latest 50cc McCULLOCK engines? Thanks Capt,n