Carburetor and Wiring Pt. 2

I researched what size jets I should be running with POD filters and a 4into1 exhaust.  I came across a great channel on YouTube called TheMotorcycleMD.  He specializes in vintage Hondas and has an awesome array of service videos.  In one of them he addresses how to tune the carbs when running POD filters and happens to mention the jets and setup for carburetors on a 1981 CB750K (thats what I have!).  You only need to open up the primary and secondary main jets.  The primary goes from stock 68 to 80 and the secondary goes from stock 102 to 116 (the closest one I could find is 118).  I got these from Randakks as well.  

Jumped into the totally-not-panic-inducing carburetor rebuild.  I separated the bodies and disassembled each carb, making sure to cleanly organize each one.  I broke them down until every metal piece was free of any rubber/o-ring.  One carb at a time I dipped all the metal components into a carb cleaning dip for about 2 hours each.  I scrubbed the outside surfaces and lightly brushed the internals.  I cleaned the jets that would be remaining with a guitar string, steel wool and more carb cleaner.  The primary and secondary jets were replaced with the new sizes.  All the gaskets, o-rings, diaphragms and springs were replaced with an overhaul/rebuild kit from Randakks.  

I painted the carb brackets black and put the bodies back together heavily referring to the thorough and entertaining MacGregor Carb Cleaning Services manual.  Bless that man.  I followed his procedure for aligning and syncing the carbs without a pressure dial bank.  I will fine tune sync after I see how its running.  TheMotorcycleMD said for the 81' CB750 he did with POD filters that he got it running great at 3.5 turns out on the fuel/air mixture screw, so I will start there.  

I needed to finish up the power system by connecting the alternator.  The alternator wire clips onto the oil pan bolts.  I had left off the oil pan because the bottom gave me a flat surface to lift on.  This was a pain with the exhaust in the way so I had to remove that first but then I got the new oil pan gasket on and torqued the bolts.  With the alternator cable routed I extended the wires and ran them up against the right side tube, hidden from the "presentation side" of the bike.  I connected the alternator to the reg/rec.  Then I connected the remaining inputs and outputs of the m-unit and ran them up to the front of the bike.  

The horn gave me a bit of trouble, mostly just because I didn't pay attention to how they operate when mounting it.  There are two screws you use to tune the horn, one of which is used as the mount.  I had turned both of them too tight while mounting which locks up the horn, keeping it from vibrating and making a sound.  After taking it off and tuning it, I was able to carefully remount it without messing up the tuning.

Got the front end completely wired up.  The right side clip on has the right turn signal power, brake switch and m-switch for the starter, right side turn signal and motoscope Tiny configuration.  The left side has the left turn signal power, clutch switch and m-switch for the horn, left side turn signal and high beams.  I drilled holes in the bars, deburred them and ran the lines through.  To reduce wiring I grounded the m-switches to the bars through the switch housing.  I had to shave off some of the black anodizing to ensure a good connection to the bars.  The bar cables meet up with the headlight, motoscope tiny and speedo cables into the main loom that enters the front side of the tank.

I made new NGK spark plug cables and installed them with new NGK spark plugs.  Getting a lot of components to hide in a space that it isn't designed for is a bit challenging.  You have to make sure the cables are sitting in the right spot as you slide on the tank or you can end up pinching the wires.  When everything was connected I wire tied the cabled snuggly together against the frame tubes.  Any wires that were too long I looped together, wired tied and stuffed them in the cavity thats at the top of the frame.  As I mentioned in the first wiring blog, I wired everything in a way that it can be replaced, nothing is hard wired in without a connector.  That being said, it doesnt mean it wont be difficult to replace it with everything being secured with wire ties, electrical tape and braided wire loom.  

Wiring up the Motoscope Tiny was a little tricky with the leads being so small.  I got away without having to add the included speedometer sensor and wheel magnets.  I found an Acewell analog to digital cable meant for their gauges that I hacked to be compatible with the Tiny, which i'm happy with because it maintains a stock look.  The only discrepancy I encountered (which was my fault) was whether the speedometer sensor connects to ground or +12v.  The included manual is in German and says to look for the manual in english online.  I assumed the first googled document was correct but turned out to be the wrong version.  Their older units connect to +12v while their new units connect to ground, shown in German on the manual I had.  Swapped that cable around and it was working just fine.  

Doing the first test for wiring up the speedometer almost gave me a heart attack.  I connected the power, switched power, ground and turn indicators w/ the diodes.  I powered everything up and everything turned on and was operational for a few moments, then everything started flickering and seemingly the power to the front half of the bike went dead.  Then the m-unit started flashing and wasn't behaving either.  I tried connecting the turn signals directly to the battery to test if they were working, they were not...

I was scared I short circuited something and caused major damage.  This seemed very unlikely with how meticulous i've been.  A quick search on the internet indicated the battery was dead, which seemed unusual (at first) since it was brand new.  Sure enough, swapped out the batteries and everything was working properly.  I have been testing the system at almost every stage of wiring and wanting to show off to my wife each time, and since having the headlight wired in, that apparently can drain a battery really fast without the engine running.  Phew!  It was looking like $1,000+ in component damage... not to mention redoing a lot of the wiring.  

Cleaned up the information plates and reshaped them as they got bent when removing them from the frame.  I lightly hammered them against a piece of metal conduit.  Finding replacement pins would be challenging so im going to tap and install with M2 screws...I might eat those words when I have to tap the frame.  With the gauge complete I was just about finished with the wiring.  Just have to put the battery in the box and hook it up.  I anticipate ill have one more post before the bike is completely finished.  I have to mount the information plates, change the fork boots, get the chain on, adjust the brake lever, touch up some paint etc.