swan said:Thanks all. I have had several nibbles, but no bites yet on the sale. I may go to E-bay next.
NeightRG said:I'll be watching this build very closely... Closer than most. Looking good.
swan said:I am having a challenging time getting my bike to idle correctly with individual K&N pod filters. There are dozens and dozens of threads online (Do the Ton, SOHC, Yahoo Auto Groups, et al) discussing this very problem and most say it cannot be done. It can be done and I have successfully run pods on three other CB400f's using stock exhaust, dropping the needle clip one notch and running 80 or 85 main jets. This bike has a repacked Dunstall replica muffler (which sounds awesome!), stock 4 into 1 header, 80 main jets, raised the needle one notch (lowered the clip, enriching the mixture to compensate for more incoming air) and a #38 pilot jet. I have quadruple checked timing, ignition, valve clearances and confirmed there are no vacuum leaks. The carbs, floats levels all passageways etc have been meticulously cleaned several times and set to spec. I am at 700 feet elevation and it is generally in the 50's farenheit when I am doing test runs and plug chops. The bike runs extremely well above the idle circuit, but down low it idles high, hangs, then drops down to a too slow of an idle. This has nothing to do with mechanics of the carbs (slides, springs, throttle cables etc) I believe one or more of the pilot jets are fouling, causing the idle to drop. This has made synchronizing the carbs at idle difficult.
Well, last night I did a series of compression tests with the engine cold, wide open throttle (WOT), cold with a bit of oil squirted into the cylinders and WOT and after I ran the bike around for awhile. Cylinders 1,2,3 were consistently in the 130's psi on all tests with my cheapie compression gauge. Cylinder #4 was 75 psi cold, 85 with oil added and 80 psi after running, telling me there was a leak in the valves, not the rings or cylinder on #4. I checked the torque on the cylinder head and all bolts were tight and to spec. There are no air leaks around the cylinder head or gasket area. So, off with her head-I ripped her down to lower end last night. I knew the chamber of cylinder #4 had some pitting and corrosion which came with the bike. I did lightly lap the valves with rough and fine compounds when I rebuilt the motor.
#4 on the right, note the pitting.
What I discovered was some of the pitting and corrosion was also in the inlet valve seat of #4, allowing for a slight leak, causing the low compression reading. In a dark room, I shined a strong led flashlight into the inlet and exhaust ports and discovered two tiny light leaks on the inlet valve seat, the culprit of my compression leak. If I did it right the first time, I would not be doing this now.
I am meeting with a machinist friend today who has the proper sized valve seat cutters. Hopefully, we can lightly cut the valve seat in order to remove the two small areas of pitting without having to replace the whole valve seat (time and $$$$).
As long as I am at it, I am replacing the kick start quadrant with a slightly used one with better splines than my original.
With 4 cylinders of even compression I should have an easier time dialing in and synching the carbs and fixing the idle problem. I'll post my results, stay tuned....
redlabel said:Hi Swan!
Love the build and quality of your bikes!
Can you get original Honda jets in the correct size if you run pods and aftermarked exhaust?
I have been looking at these kits from Sigma on e-bay but not sure about the quality.
fenixv8 said:Dont mean to intrude on this thread but i am in a bit of a bind and this thread is the onlyone that I can find that related to my issue. I bought a 1977 CB 400f and it had a really free flowing exhaust and shitty pods on it.
It was running rich all around plugs fouled. I ordered a keyster kit (before reading this thread) opened the carb up and realized a keyster kit was probably installed on it. I replaced all the internals of the carb with stock honda parts now and it still is running way to rich.