I used a walbro too. Still waiting on parts. Should be here end of this week. Are you replacing bearings and circlips too the impulse needs replacing I an using r3? My 250 leaked could not get a valid test around the bottom of engine in one side the plates would not seal. I am considering getting a used oem motor base. It Will run good I bet. I got 3 chains and a 18" bar so when time comes it can go.I thought the MS250 kit was pretty easy to build....It ran good after I used a original walbro carb....Clutch was way off...would not engage until 7000rpm. I replaced it with oem clutch from parts pile and all was well. I have 180 coming in mail. The 440 and 660 kits are much better. Only decompression valve and one chain tensioner so far on 6 builds.
Do you have plans to build a ms361? Unless they pop out a 460 or a 200t a 361 might be in my future.