"Project Bantam" - Arts and Crafts

I've finally amassed all the parts required for the Briggs&Stratton 14FB engine overhaul.  The main bearings look good, and the piston ring gaps are within spec using new standard size rings.  One of the exhaust valve keepers was rattling around in the tappet chamber when I opened the tappet cover last month.  The exhaust valve seat was rather rusted and required significant lapping to get down to good metal.  A quick grind on the valve stems put it back within gap specification.

exhaust = 0.015"

intake = 0.008"

The gudgeon pin is still tight and the piston looks good as well.  It can be put back in with the new standard size rings.

I went with a two-tone paint job on the block.  The fins were rather rusted, so I wanted to make sure they got painted and stayed painted.  So they got a 1200'F rated exhaust paint in silver.  The crankcase got a 500'F rated engine paint in black.  The exhaust elbow was rusted fast, but the threaded adapter to the exhaust pipe still had good threads, so that's staying.  I just need to obtain a new mating nut and olive for the exhaust.  It looks like an electrical fitting.

I had my son help with the arts and crafts.  Making measurements and cutting gaskets is a tedious task, but still enjoyable.  I started with some relatively thick gasket material for the tappet cover, point cover, and oil pan.  The bearing housings require some adjustment based on axial float of the crankshaft.  I made them out of thin material as templates.  I can go back and duplicate these easily when I get the crank set in, if the float needs increased to meet spec in the manual.

On closer inspection there are marks on the inside of the timing gears.  It looks like someone has had this engine apart before, since the cam gear has a awl scratch on it pointing to the correct place between the timing teeth.  The manual says to set the timing based on the outside of the gears, which is presently obstructed by the main bearing.  Timing will have to be set by the inside viewing through the bottom of the crankcase.

Sunbeam S7 Deluxe tuned and adjusted

The engine has been hard to start, and hasn't seem to had the right amount of torque at low revs.  I figured that it was too far advanced, and I should back it off some.  I'm not halfway between the original mark on the distributor and where the book said to set it.  It runs much better.

Also, the clutch travel wasn't right, so I took the blob of tape off the handlebar to find that someone had adjusted the clutch cable with a washer holding the sheath out away from the handle.  That explained a lot.  I removed the bodge, and then remembered that the clutch slave arm wasn't symmetrical.  Its actually made so that its bent a little and can be put on either direction.  This meant pulling the rear fender out of the way, and undoing the jam-nut and screw that holds the arm in.  With that done, I flipped it around and then readjusted the clutch adjuster so that I got better travel and engagement at about where I wanted it.  The clutch is much better now and the bike even shifts better since its disengaging better.  Previously it would clunk pretty loud when changing from 1st to 2nd.  Now its smooth.  Probably smoother than my Guzzi.

I still haven't taken it very far.  The engine runs hot even though its running a little on the rich side.  The rings are likely still rather tight.

Armature and timing cover removed

I finally dedicated some time to taking the flywheel and armature off.  PBlaster is a great penetrating oil.  Just a few squirts and a day of waiting and everything came right off.

Well, I did have to fashion a slide hammer for the armature.  I tapped out a 7/16" bolt thread into the armature just a few threads.  Then I made this slide hammer and it came right off with a few pulls.

It here's what I found when the timing cover came off.  Not much to see, but I'll have to line up the timing marks to see how everything is supposed to go back together.  Long bolt goes in the top of the timing cover.  Why its chewed up, I don't know yet.

The seals are naturally petrified.  The timing cover seal has apparently no metal backing built into it, since it sits inside the timing cover and needs to be pried out rather than slid out the side.