I have a similar setup to yours. I do have a arc billet rod but anyways carb works just fine. Used a 130 main jet clip in the middle grove (the way it came ) and the stock pilot should work I think it is a 15. Idle air screw adjustment should wind up between 3/4 out to 1.5 turns out if pilot is correct.
I milled head just to get it flat with a fire slot that I have since found out does nothing. It has a manifold that looks a lot like the one above with the mikuni, isky 230 cam with 260 lift and a home made header. The nice thing with those carbs is that the slide is narrow and tall so you have a lot of granularity with the throttle. I have used them on bone stock briggs 5 hp with equally good results. But I would not run a HS50 without the govenor unless it had a good rod in it, the stock rods don't like revs over about 4500 rpm.
Ok..so yours isn't similar to his bone stock motor....got it. Briggs have always been able to run a bigger carb. Food for though..the Black Widow runs a 4hp with a 19mm Dellorto....(without a governor). And the 69 Roadster runs a 22mm (guessed it..no governor)on a big block. Comparing Briggs with Tecs is like comparing apples and oranges. But this is just my opinion and not of this stations....
Yes, I have arc billet rod with the govoner removed. (Cylinders have been honed, fresh rings, head studs, port work, made my own intake) Anything I can do to gain something extra power. (I was going to run alcohol but I would have to advance the timing etc..) There is still plenty of room to shave the heads down. The head gasket that I am using is also about .004 thinner than the stock gasket. Im really looking for a baseline for the carb.
I wanted to play it safe so I just knocked .010 off. I can always knock more off. I have a couple of spare heads so I will knock some off those and can switch those out later. I didnt get a cam because this is going on a twin engine go kart and two cams would be close to $500. I also have a custom stainless header I built (I used the biggest tubing I could). I am building a custom fuel tank for it so I am using a mikuni fuel pump.
Here are some pictures of it. Going back through my email the cams might not be as expensive as I thought. If I get the cams what else will I have to get for them? When I had the kart together two years ago it went 50mph with hs50's that did not really run right. I would like to go 60mph with it. I've rebuilt the cart, new bearings, machined new steering bushings, fabricated a new dropped front end, new rear axle, steering parts, paint etc...
