The Sv's that I have came with WT 694s (chokes) on them. They have an external pulse line going to crankcase. On one the brass insert in the crankcase was completely stopped up with black crud, right outta the box, took a drill to get it out. I resealed everything with RTV, carb gasket, reed blocks, plate on side, etc. Took reed s out & checked them, laid on flat glass to make sure sealing, Last resort, rubuild carbs with complete kits, new diaphrams, needle, spring, removed lil freeze plugs & cleaned hi & low jets. After overhaulin carbs they ran for a while, 20 minutes, one good tank, then back to same ol problem. Have to screw out on hi side 3 + turns to get to run, low side about 2, turns, plugs (have tried 'em all NGK, Champion, Autolite & 3 heat ranges) show rich. BUT they won't run when you try to lean down.
Have dual filters, chain saw filter for one clunk, Big metal for other, Sullivan Crap Trap on main line, carb screen is clean. Compression is good.
Reset the timing, tried 28 to 30 degrees BTDC, used degree wheel, & timing device.
It's got to be the carbs, something ain't right. That's why I'm looking for a REAL Walbro substitute. Some say the Wt 817 or 741 may work That's what's comes on the newer ones. I have tried a brand new geniune Walbro WT 433, had to substitute pulse cover from WT 694, it wouldn'r run it!!
That's why I'm at the end of my rope!! Help, Please! ANyone???
I have a good mind to box 'em up & send to Capt M Com!! or BP Hobbies, if they'll even work on them!!