So, it with winter coming I decided that I would get a few things done while the weather was still warm enough to work. I had not been riding too much and finally I had a chance to take care of a few things. Since the rebuild of the carbs, I noticed that I was not getting quite the high-end performance I had expected with a nagging miss around 3000rpm.
It seemed like a good idea at the time
Fix the obvious
Points and condenserI started by replacing the points and condenser. Not a bad idea. The old ones were so shot I could see them arc across the points themselves to the arm that holds the points. Hey, that may have been the miss. Or not. It certainly helped and thanks to the magic points adjustment tool ($24 well spent) I went for keeping with mechanical timing. I guess I just like the thought as opposed to an electronic system that just flat dies by the road with absolutely no options. Still not satisfied I tried to balance the carbs with my home made an manometer. What is that?
Detour: The manometer from hell..for $6
To measure your vacuum on the carbs and balance them you can spend a lot and get a fancy set of gauge that giggle and bounce making it really hard to see if things are steady. That costs around $60. Or you can spend $6 and get a more accurate gauge. Attach a 4 foot length of 1x2 perpendicular between a couple 3ft lengths of 2x4 so it sticks up in the air and the base is stable enough so it does not fall over. buy 10 ft of 1/4 in clear plastic aquarium hose. and loop it from the top of the 1x2 back up to the top. secure it gently with zip ties. Fill it with some automatic tranny fluid so you have about a foot in each column of tubing. Secure the top. You might have to use a couple short lengths of fuel line to keep the upper ends of the tubing from kinking as you bring them down to the bike. now when the bike runs, the carb drawing the most vacuum will pull some of that ATF up its side of the loop. Instead of trying to read a little bouncing dial you have a nice stable column of fluid that probably moves one inch for every 1/32 inch giggle on a needle. It is really precise. Pure physics.
Fuel flow...or not.
So, again, that helped but not cured. Time to check fuel flow because it seemed as though one carb might be starving. Pulled the petcocks and found them to be in poor shape. Replaced one outright ($45) when dumbo broke it while tightening it. I will not tell that story. Ever. New screens, one new petcock...what could be a better time to look a the tank.
Tank sealing 101
I looked in the tank and realized that years ago someone had sealed it and that seal was shot. Gross junk. So, here's what I did.
- Get a jar of naval jelly ($6)
- Gallon of acetone ($10)
- Box of baking soda. Don't use your spouse's from the kitchen. Get you own. (Tip for a 35yr marriage #43)
- An 8oz can of POR-15 49216 tank sealer ($13)
- a short length 18in or so of brass chain. small stuff, that figure 8 type.
- 2 rubber stoppers that fit the petcocks...BAD MEMORY..I thing they are 1/2 inch or so. Measure yourself. ($3)
- A "pick up tool"
- Air Compressor
- Hair Dryer or Shop Vac
- Enough protective gear for a chemical attack.
- A couple dark nights with no neighbors around.
Flush the tank with water. Add the chain and shake that tank with water to bust up all the loose old sealer and rust. Repeat until dawn or the only thing left in the tank is whatever sealer is still sticking.
Add the acetone and put the gas cap on. shake it every few hours for a day or so. The old sealer is turning into sludge. Drain that mess back into the Acetone can and Flush the tank with water. If convinced its all out of there, pull out the chain.
Now, add the Naval Jelly and warm water. Half tank. slosh it to break up the jelly. This is galvanizing the metal with an acid. fill it to the top and let is set for a day. Drain it, flush and fill with water and baking soda. Now the acid is neutralized, and your driveway is the cleanest it has been in years.
Drain it, flush it with water like crazy and blow it out with Compressed Air. Dry with hairdryer or shop vac blowing into the tank.
Follow directions on POR-15. You've already cleaned and prepped the tank just dandy. The directions are shake it, pour it. tape off the opening for the gas cap and start methodically turning tand tilting that tank. The BMW has a 6 gallon tank and you are going to get about 2-3 oz of extra sealer when you drain it finally. It is a thin, thin coat. Let that sucker dry for 96 hours or whatever. Don't rush it. So for $35 it is clean, galvanized and then sealed with aluminum powder suspended in a fuel proof paint. Yipee, it will last forever and so much nicer that that gooey plastic sealer that was in there before. Yellow mung.
Back to the Petcocks and some other thoughts.
Reinstalled the screens and petcocks plus...a new set of in-line filters ($10) and have great fuel flow. Still a little missy, so time to re-check floats. I think they were a little low and might have given it some fuel starvation? Anyway, it seems better. Time to do some other checks or just have a pro play with it for an hour and get it right. I'm pretty happy with the valve clearances and associated noise. Its been a few years since I checked them - so it might be time before I spend money on a real mechanic. Something I can do and feel good doing.
Starter problem - not so fast! It's the cable, stupid.
So I was doing some checks, balancing the carbs by letting them carry the idle individually until they would just die after a few kicks. Really using the starter a lot. All of a sudden, I got the chattering sound of the bendix not fully engaging the flywheel to the point where the sucker would get full voltage and turn!..and its not the first time. A few weeks ago, I changed out my old Bosch for a Chinese knockoff Valeo. Yeah, I know. But it was doing this same thing. Chattering. It stopped when I put it all back together and the new starter seems okay. Now its a few weeks later and its doing it again! Then I hear it. POP... I spotted a freaking spark off my negative ground cable! Until I moved it around I had no idea it had rotted and broken by one of the connectors. Probably 1/3 of the wire gone. Well. Replaced the ground wire and it starts like a champ. Obviously that old Bosch was not the problem and now I have a spare starter handy for the day the former democracy demonstrators turned laborers at Tienanmen Industries Starter Factory #7 located near an old above ground nuke test site in the Western Deserts fails me. What do those people want? A 12 hour day and a 6 day week?
So that's almost the end of the story