Has anyone tried converting the MDS 148 engine?
I have one, new in the box that I want to make the Walbro adapter for. Looks like it doesn't have rollers on the conrod lower end, but not a problem as I'll be doing the 20-1 mix for it anyway.
Any ideas for this engine greatly appreciated.

John

MDS has a bit of a hit and miss history. When good, it's a powerful engine.
use 1 in 8 oil. 1 in 20 is cutting it thin.

Wow, 8 to 1 ratio? That's gonna have a seriously tough time making it past the high and low needles on a Walbro carb. Probably have to open em to about what, maybe 5 turns out??
I've run a K&B .61 on 16-1 Belray oil. You sure?
Well, I'll try it. Guess I better buy stocks in NGK ME8 sparkplugs. LOL

John

12.5% oil is not too much for a small plain bearing engine. 7% oil in small engines is quite common with needle bearings.
Most walbro carbs will manage this mix quite well. If not, slightly raise the fulcrum lever height.

I was thinking about raising the lever about 10 thousandths or so just to be on the safe side. Last engine I ran alot of oil in was an ASP 108. It ran well on ignition and no bad habits except the usual touchy stock carb needle.
My K&B 61 with Perry carb also worked well until it's demise performing a spectacular figure 9. Oh well.

If I drill and tap the back cover on the MDS, what orifice size in the fitting, if it matters, do you recommend for the Walbro pump to operate correctly?

John

The MVVS pulse fittings are M4 with a 2.2mm orifice. These fit all their engines.