Sunday, May 30, 2010

No More Pulse-Air System

Since I still not supposed to ride yet, I spent the afternoon working on the bike. Pulled off the air box again to remove the Pulse-Air system. This system sends fresh air into the exhaust port right next to the exhaust valves and is apparently one of the culprits causing my valve recession problem. It is fairly straightforward to remove and the steel fittings threaded into the aluminum head came right out. Last winter, I tried removing the fittings and they wouldn't budge. This time, they were barely snug. Why the difference? Anyway, I need to try and find some 5/32" rubber caps to plug the vacuum ports on the carbs and on the air box and some rubber caps to plug some rather large holes in the air box where the plumbing fitted into. I also need to try and find some metric plugs to thread into the head next to the exhaust port. The overall look is much cleaner without all of the extra plumbing. I also took the opportunity to clean all the caked on grease and dirt from the transmission, air box, air hoses, etc. Basically, 60,000 miles of dirt and grime. It looks a much better. I'm also replacing all of the fuel lines, eliminating just about all of the vacuum lines (they are part of the Pulse-Air system), replacing a cracked stainless exhaust crossover, and while I have the time, The clutch cable. The fork gaiters will have to wait for this winter since that looks like a much more involved job. I will take the opportunity to rebuild the forks at that time. The BMW replacement parts are heavy rubber while the gaiters currently installed are thin plastic ones. Kind of like what you find on cheap aftermarket truck shock absorbers. I also still need to rebuild the fuel petcocks since I finally have the parts. Something for tomorrow. I've been asked why bother with an old bike such as this 1983 BMW R100RT but I really like the simplicity. No fancy electronics or complicated systems, no coolant hoses to leak but then again no advanced safety systems such as ABS.

When I drained the tank, I monitored the fuel flow to see if a vacuum would build up in the tank but it never did. I don't think the problem is the tank vent. Also, the vent line running from the tank to below the swing arm isn't plugged. The fuel flow was more than adequate for the entire three gallons left in the tank. I still don't have e carb parts yet so that is going to have to wait. Just for grins, I took off the ignition module and the thermal paste was reduced to yellowish-white dust. The paste ensures good heat transfer from the module to the aluminum heat sink to avoid overheating and eventual failure. I guess I have just been lucky that I haven't had any ignition problems related to heat. Tomorrow, I'll pick up some thermal paste from Radio Shack. I wonder what else I should check?

Sunday evening - I had a nice relaxing afternoon working on the bike. I found some expanding rubber plugs that fit the holes in the air box perfectly. Just tighten down an allen head screw and the center of the plug expands to prevent the plug from coming out. I found these at an industrial hardware store that was actually open. A Carquest auto parts store had the 5/32" rubber caps for plugging the now unused vacuum ports on the carbs, and the local Napa store had the M16-1.5 oil drain plugs that I used to plug the holes in the heads from removing the Air-Pulse system. I had to cut them down a bit but they now fit perfectly. I'll need to try and remember to torque them down when the heads are nice and hot. The engine now looks much cleaner without all of the extra plumbing. The exhaust crossover was kind of rusted in place and removing it required a vice and a hammer. The new crossover pipe was about two inches too long so I cut it down and re-cut the horizontal slots enabling the clamps to function. I then reassembled the intake system inluding a new air filter then put the exhaust system back on. Now it was time to rebuild both of the fuel petcocks. This basically amounts to taking them apart, cleaning them out, replacing all of the rubber parts inside and reassembling. About ten minutes each including carefully cleaning the screen inside the tank and trying to figure out how they came apart. I then adjusted the valves using my new color coded BMW thickness gauges (0.10 mm and 0.20 mm). These were missing from the tool kit and I noticed that the Beemershop carried them. The goal is to carry all of the tools I would need to do emergency repairs and periodic maintenance. All of the valves needed adjustment since I used SAE gauges the last time I adjusted them. Close but not quite the same. Both exhaust valves have not tightened so I'm still good. When the gap needs to be adjusted every time, that would be the sign to stop riding and pull the heads and send them off for rebuilding. I enjoy doing repairs but for rebuilding the heads, I'll let someone with more experience take care of it. I noticed that the vacuum line was almost cut in half from age and wear. This would have been a serious vacuum leak making the bike run very lean. A bit more on the right cylinder than the left. I wonder if this was contributing to my problem. I wasn't able to get any thermal grease so the ignition module is still hanging there. Once I get that done, I can put the tank back on, put in some gas, and see if it still runs. Maybe even take it out for a ride. All in all, a very therapeutic way to spend a Sunday afternoon.

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