I've been busy lately, but finally got some more done on the bike.
I'm having many issues and have solved a few of them.
1. Front disc brake alignment. When assembled with the adapter on the fork (203mm) the adapter was rubbing on the brake. I took the adapter to work and milled .040" off the mounting tab points, and it seemed to fix the problem. Maybe the fork I have is junk, or the wheel builders messed up with the hub spacing... but the fit was nowhere near perfect as stock.
2. Clutch. Cut up a beat up old 2-3" Starret .001 micrometer to use for my clutch arm. The hole in the engine faceplate has threads, but I couldn't figure out what it was though I was thinking it was a 5/16-18. I went in there with a 5/16-18 tap anyway, and put a screw in.
I need a stronger spring. The belt will be tensioned as stock, and when I pull the clutch lever the cable will pull the arm away from the belt, releasing tension and allowing it to slip (I hope!)
3. Intake manifold. After hours of searching and researching for a B&S intake manifold designed to fit the 45deg angled bolts, I gave up and decided to make my own. For a short time I was thinking of getting into DIY sandcasting and making a complete part, then milling out the internals. Fortunately I found a couple of scrap parts at work with a flange, 1" OD and hole through, and modified them into two halves of an intake manifold. The japanese Honda knock-off carb I have from thebay has a 1.9" bolt pattern with .854" center hole, set horizontal, and the briggs is an approx. 1.35" bolt pattern with a .812 or so hole set at a 45deg angle. Have fun finding an intake manifold to fit that.
These two intake manifold flanges will be connected by a 1" ID rubber tube hose clamped on both. And maybe glued. I wish I could weld aluminum!
I still have multiple issues to work out.. need a stronger clutch spring, figure out the clearance in the back for gear shifting, and my front disc brake. The inner piston doesn't retract all the way back in (needs cleaning/oiling) and the line needs to be shortened. I guess other issues will arise when I get through these