OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines Briggs to Honda swap

Has anyone tried having the blade boss and drive pulley machined from 7/8 to 25mm to suit the Honda unit?

I was going to swap Briggs to Briggs as mentioned in an earlier post but decided not to go through with it.

I have a low hour GXV160 in the shed and can't buy the correct parts thus considered machining them.

Go for it, if you can't buy the correct parts... They put a man on the moon with hand made parts..Done correctly by a good machinist I dont see why not?...

At this point I don't know what machine you are thinking about converting, aldot. Can we have pictures of the machine, the original (Briggs) blade setup, and the blade boss you are thinking of converting please?

I made a conversion a couple of weeks ago, and it took a lot of extra work because I had to do it twice due to insufficient measurement work before I started. (I wanted to put a Honda HRU blade plate with 4 swing-back blades on my 1980s 4 height lever bar blade HR. I also wanted to lower the cutting edges of the blades 10 mm below where the bar blade's cutting edges were, so they were at the bottom of the mower base.) On the first try I somehow managed to overlook the fact that the Honda blade disk is heavily dished downward, so I put in an hour or so of milling machine time making a complicated 5" diameter 15 mm thick spacer I didn't need, to adapt the huge bar blade boss to the small pitch circle required by the blade plate. And yes, I could have just bought an HRU blade boss instead of making anything, but I'm way too cheap to do that.

In reality I just needed to drill and tap three holes near the middle of the original bar blade boss, and make a 1.5 mm thick spacer to keep the blade plate from fouling on the original mounting spigots for the bar blade. The conversion is therefore instantly reversible: if I ever decided to revert the old HR194 to original form, it would only take a couple of minutes to do it. And yes, it works extremely well so far. The point was that it's easy to miss one detail of the physical layout when you are doing the design, and end up going off at a tangent.

I have the impression that Honda's output shafts (PTOs) are longer than Briggs ones, to accommodate the blade clutch they tend to use. You will therefore need to pay careful attention to where the cutting edges of the blades end up relative to the mower skirt and bottom of the grass scroll. You don't want the blades hanging in mid-air 10 or 15 mm below the bottom of the mower, like an old Victa toe-cutter. And you don't want them 10 mm above the bottom of the mower either, like the 1980s HR194, or you won't be able to mow down to the 30 mm cutting height commonly used for kikuyu without the mower skirt burying itself in the grass so you need three guys to push the mower.

I'm still playing with this. I need to pick up a puller to remove the boss and drive pulley.

Aldo, it will make this easier to follow if you post what kind of mower/slasher is involved, and what model Briggs it has been using up to now. If you post the full model/type/code, we may be able to find the parts list. Who knows, we may even be able to find a parts list for the slasher, and bring up a sketch of the boss and pulley.

I think its a 100mm three jaw stanley brand from supercheap. Cost me less than $50 if i remember right. Does a good job.


If you modify the heels on the hooks on the end of the jaws slightly with the ginder it will even do the victa bosses on the short shaft Tecumesh motors.


Ive got a bigger two jaw I do most stuff with, but that stanley has done a good job. Guy at the mower shop told me it was the one to get. Its never not got a boss off that I have tasked it to remove.


Go and buy a couple of spare 3/8 UNF bolts. 2" & 2 1/2". If you have a lathe, drill a point into the top of the bolt head to locate the nose of the puller shaft. If you dont have access to a lathe you can do the same with a drill press reasonably acurately. You could do the same with a hand drill too i suppose. It does not have to be real deep just enough to stop the puller walking.


Put the bolt in the crank and wind it in a fair way. Ring spanner on the head of the bolt. Put the puller on. Then as you wind the puller the spanner will hit the arm of the puller and stop the bolt winding in any further.



It has been posted on here that another option is to clean up the cranksahft above the boss, the drive the boss up the crank, clean where it was on the crank the slide if off by hand.
Ive had limited succes with this, works well if the shaft is in fair shape. If not its a hell of a lot of work.

Cheers, Bob.