OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Victa Lawn Mower Frames briggs onto victa base

please set my mind at ease; I was advised by a retailer today that a briggs 850 engine will not fit a victa 550sp base - this is wrong isn't it? Need to be sure b4 I buy one

Mate depends on whether the mower was originally a 2 stroke or not, if not you will need a new blade boss. Also you need to find a Briggs motor with the correct lenth crankshaft

I have a 4 stroke boss ordered, just need to know what the victa shaft length is to get the right briggs. I'm looking a the 850 6hp with either "Crankshaft Extension: 25mm x 3 5/32" Length, Tapped 3/8" - 24, 2 Woodruff Key(s) and 1/4" Keyway" OR "Crankshaft Extension: 7/8" x 3 5/32" Length, Tapped 3/8" - 24, 2 Woodruff Key(s) and 3/16" Keyway"
I'm guessing it's the 7/8" shaft but need confirmation - the engine no is 121Q72-0020 850 Professional Series

Not sure about the 7/8" ive only ever seen 3/4" or 1" motors. But have not seen much new stuff. Most are 3/4 and if i remember right the Ultima was a 1" shaft. Best wait till you get the boss.



A power Torque motor is around 2 1/4" (52mm) face to face. (a bit hard to measure free hand)

An old victa 4 stroke will have a 1 5/8" shaft (47mm) you gain about 5mm in the seat of the blade boss.

Older morrisons and masports 2 3/8" shaft (62mm) Later Victas also use this with a 15mm spacer ring.

Rovers, MTD and flymo etc 3 1/4 (81mm) (could be 3 5/32") so that would be a fairly high spacer.


Best thing would be to grab a couple of steel rulers and have a good measure when the crank boss turns up.

I would be aiming for the right shaft length, the longer it is the easier it will bend.
Those crappy 24" MTD slashers with the 3.75 sprint motors on them were only a 3/4" shaft x 81mm, ive seen a couple of bent ones. Seen some regular mowers with the longer shafts that were bent too.