Been fiddlin' for months now...no matter what I try, my plugs foul in just a couple minutes.
This has made for a considerable cost in spark plugs...
I have waffled between this being something in the electrical ignition, and something in the carb. After replacing everything in the ignition (points, condenser, plug wires, plug caps, coil, ignition wires), I put the blame on the carb. Even after trying every possible setting for float and needle, I'm mostly-sure this is where my troubles lie.
But I had to figure this out the hard way. SEVERAL of the parts I have ordered for my Dream have been wrong (many people obviously send stuff for a CB77 thinking it's the same). The non-resistance thing in the plugs is particularly challenging...more than one NGK plug dealer has given me 'DR8HS' plugs 'coz their books show it as replacement for 'D8HA' (pile in middle in photo). It's not a replacement, it is the resistor type!
Anyhow, I've done it so often now I'm pretty sure my float height is good. I have a 120 main jet; both the jet and the needle are from my old carb as the replacement Keyster brass does not look good. I've had the needle in all settings, latest with it fully 'in' on its top notch. With new plugs, I have good spark, and the bike starts up right away (no choke), then runs great for about 2 minutes...when it stalls because the plugs are fouled as black as coal.
When running, it has no odour of burning oil, but makes a light-grey smoke that gets steadily worse. By the time it stalls there's quite a bit of grey smoke, which I'm presuming is unburnt fuel.
My Dream is a non-USA model C77. When I got it, it had a Mikuni VM22H carb on it, which is not correct (I think) and had a epoxy repair to the set screw housing. It would foul plugs, but over a matter of hours, not minutes. I got a Keihin off Ebay, seems absolutely kosher and clean.
Anybody have any advice or suggestions for me?
ideas on what happened?
Three months later...NO JOY :(
Re: Three months later...NO JOY :(Valve adjustment.
Compression. .......lm
I've got a clueNot surprisingly, LoudMouse pointed me at something useful, namely a compression test.
Took me a while to get to it, I lost the adapter for my tester and had to buy a new one. Test showed 155 both sides. Sounds good, I thought...even and high. A look at the Clymer manual, however, says readings over 120-150 means 'severe carboning in the combustion chamber,' requiring disassembly and cleaning. So, not out of the woods yet, but mebbe if I clean it, with my all-new fuel and ignition systems, I'll be back on the road...next year! CompressionHonda Shop Manual says 149.3 lbs is "normal" with 113 lbs being the service limit. Bill Silver says normal compression is 150 to 175 lbs. I think I have seen that somewhere else as well.
Hmmm...
If Honda says 149.5, and Mr Silver says up to 175, at 155 it would seem I'm in pretty good shape compression-wise. That leaves valves, which I'm pretty confident are gapped properly (I have done this on many vehicles). So - something wierd in my nice clean Ebay carb? Or - my compression is low, but then carbon build-up is making it read normal-to-high? I haven't yet made the investment in Mr Silver's CD, thinking it would be a couple years before I went for the rebuild-restore on this bike. Guess I better buy the guide and take off the top end to see what it looks like. I COULD be so lucky as to find that using those incorrect resistor plugs is the source of the carbon, not failing rings. If I clean it and there's no signs of cylinder wear, I might be lucky. But if it carbons up again, I'll have to look at the pistons-rings. And if I get that far, I guess I'll have to look at my bottom-end bearings. And if I'm going through the rigamarole to remove the engine, I might have to think about a strip-and-repaint on the body. We'll see how the time and energy hold up. Thanks guys, I'll keep you posted.
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||