TOPIC:

Dang. Sucks when you're trying so hard to solve a problem and this is the thanks you get.

Fuel. Fire. Compression.
What is it losing randomly?

Reason i ask is my son had a similar situation going on with his HD. Random fails. He had that thing in so many dealerships in the span of a month. Fixed! No wait. Doing it again.
I went around and around with him on this. My rational was if it's totally random then unlikely fuel or compression so most likely fire & we tried to no avail. He was so pissed he was about to tow it to HD & tell'em to keep it. One last shot i asked & we went over the entire bike. That's when i found a small wire crimped under his solo seat against the frame...
Fixed. Finally.

Point is: if you've tried all the obvious & most likely then maybe it's time to try the least likely?
Had you done anything recently before this began happening; however unrelated?

Good luck. I lnow how frustrating it can feel.

If you get a chance a picture of the plugs may help.

- I figured it would eventually come down to tracing the harness out or even making a new one. but I really don't want to. And for a knicked wire to be the culprit, that would mean somehow the primary side of the coil is not getting sufficient voltage, and not making spark. the v at the coil when it won't start is the same as cold starts when it fires up. that alone pretty much proves this is not an electrical problem. (headlight cluster taillight work blah blah bike still has electrical power when it dies out)

my gut/sixth sense says it's something fuel related or this "vapor lock" shit. I have been building shit for a long time and never heard that term, so I feel it has to be in quotes. Sometimes when it won't restart, it will fire for a fraction of a second as if it were starting cold, literally maybe fire each cyl once then won't restart again. battery will drain trying.

I'm going to back all the valves like a half turn out just to double make sure, it is tricky to set the exh valves correctly.

how the hell do I upload pictures from an iPhone. I will go to town with pictures if someone can help. no the attachments thing does not work.

I see that you are getting 12v to the coil and that you have spark. However, that doesn't rule the coil out. When an old coil gets hot, it can fail internally. Are you seeing good, fat, blue sparks when the coil is hot? If not, the spark may be too weak to get the job done until the coil cools down.

Vapor lock is usually the result of the fuel line or carbs getting really hot, causing the fuel to boil in the line. This is pretty rare on motorcycles since the fuel lines are well insulated (rubber) and the carbs are rubber mounted. What more commonly happens is that the fuel line has a small kink, or the wrong type (paper element) fuel filter was installed. Neither seem to be the case here.

Coil is brand new Dyna gray 2.2 ohm. I have 81, electronic ignition.

Just checked compression 135 both cyl
Plugs dark black and sooty, last startup burnt a bunch of oil. other than old valve guides idk why. Don't really care about guides at the moment

Pics of the plugs?
Steve

The 440 has an igniter in the ignition circuit, yes? If so, could it be malfunctioning?

Yes has igniter. Battery wasn't tip top fully charged but have 12.1 at battery 11.6 at coil. But that's what I have when it will start and that's exactly what I have when it won't start. Battery is brand new
Anyone know igniter testing off top of head?



I just cleaned the shit out of them so a picture won't tell truth porcelain is dark dark brown. unless I go for a ride quick get stranded then hike home flirt with cardiac arrest in this hilly terrain. Was going to wait till it gets darker and cooler. I've lost like 10 lbs building this bike.

All my electronics are floating temporarily. I need to be able to reliably ride to friends shop for frame and exhaust welding and electronics tray. Once everything passes ops check, I'll either turbo it or sell it and build a 4cyl. Turbo and carbs is real fun,

Could any of the electronics that are floating other than rectifier need a solid mounting ground?

swest wrote: Pics of the plugs?
Steve

Main jet is too rich it doesn't really want to ring out. I'll go one step lower

When I was burning oil, (bad seals) I went down two steps on the pilots. Did a valve job and it was too lean. Wouldn't run for SHT. The exhaust was loud and hollow sounding. Went back up and it was back to normal. Then I started on the mains.
Steve

Check your valve lash.


.

TexasKZ wrote: Vapor lock is usually the result of the fuel line or carbs getting really hot, causing the fuel to boil in the line. This is pretty rare on motorcycles since the fuel lines are well insulated (rubber) and the carbs are rubber mounted. What more commonly happens is that the fuel line has a small kink, or the wrong type (paper element) fuel filter was installed. Neither seem to be the case here.

unfortunately the aluminum intake manifold can get very hot and transfer the heat to the carb if the rubber connection to the carb is small enough to allow the manifold and carb to contact. There can also be the problem of fuel condensation on the aluminum intake (I get about 10 ml inside of mine during normal operation with a much smaller piolet, and much leaner low throttle range. .The large size of the piolet and high needle position may be preventing the excess gasoline from dispersing from inside of the intake manifold at idle or low-mid throttle. I personally have found that middle needle clip position to be grossly rich at low throttle with any reasonably sized main jet. It definitely looks like you are on the very rich side but That's about all I can offer.