Hello everyone,

Sorry for the big post, but I've got problems.

After sitting dormant a few years I got my bike going again. Carb rebuild, new gas tanks, new oil tank, new coils (single fire), complete re-wiring. I put fresh oil in the oil tank, but didn't think to drain oil from the crankcase. Evidently there was a bunch in there because on the first ride it puked oil all over through the air filter (case breather routed to the back of the carb intake).

It ran strong right away. Little carb fiddling and I took it to work and back the next day. No problems initially other than a little more oil puking, everything ran good on the way there. On the way home it ran ok, but had a loud backfire one time. I figured there was some adjusting to do but didn't figure anything bad was happening.

Pack the bike up and took the whole family to Florida for them to visit the in-laws and for me to go to Bike Week. I spent the whole time with the in-laws because something went bad on the trip to florida (in the back of my pickup).

The basic problem is that it dies suddenly. No stumbling or weirdness before death, no immediate warnings, just dies. This does not happen when running fast, like on the highway. It happens when slowing down, like on an exit ramp coming to a stop, or when riding at a slow steady speed, like around town. Will also happen if I start it up and let it sit in the driveway idling. The time is always different. Can idle for 2 minutes or maybe 6 minutes. Never dies if the rpms are up (and riding, haven't tried high rpm sitting in neutral).

More clues, but intermittent and don't know what to do with the information:

"Sometimes" when it dies it'll make a big hissing noise several seconds after dying. Not always. I was thinking the vented cap was messed up and have popped the cap immediately after death with no hissing, so no pressure or vacuum immediately after dying in the tanks. Maybe the hissing was through the carb? Could be, but I don't know what that means if it is.

It has a slight miss when idling. And when riding slowly with low RPMs, will sputter just a little and feel like it's lunging a bit. I have an electronic ignition and I haven't touched the timing at all on the bike. Feels like the time could be off, but certainly not off so far as to cause the engine to just die with no warning. Check and adjust of timing is on the schedule for tomorrow morning.

Sometimes (again with the "sometimes") it will sound like mild backfiring like bubbles popping out the pipes. This also happens sometimes when I stop the engine myself. Flip the switch, engine stops, and then a couple seconds later "pop" out the pipe. Not a big bang, it really sounds like a big bubble popping.

Something else that I just now thought of while typing all this is that the crankcase vent has a Krank Vent breather valve inline from the crankcase to the air filter. With the oil it's puked, that thing could be gunked up. Need to check it. will a plugged crankcase vent cause some of these problems?

ANY help is appreciated. I'm going to check the timing tomorrow and clean the crank vent. I've turned the accelerator pump off on the S&S carb to take it out of the equation but didn't make a difference.

Thanks
Dave

 

What year and model is your bike? Have you noticed if when it dies you lose all your lights? Or is it just the motor?

 

I had a intermittent stalling problem similar and it turned out it was the stator. Not saying for sure but that's what mine was.

 

It's just the motor that dies. Lights are still on.

The bike is homebuilt, no particular model. It's a 96 inch mostly S&S evo. Case breather, with a Super G carb. Single fire with a Dyna 2000 ignition.

Cleaned out the Krank Vent today. It was good and clean, just a little oil residue, so not my problem. Had to go into work, so didn't get anything else done.

With all these weird and somewhat intermittent symptoms, I think I'm just going to pick one symptom and try to find the fix for that. Then see what happens and move to the next symptom. First pick is the surging and popping in the exhaust (and the rare backfire that occurred once or twice). So what causes that?

Thanks for the replies
Dave

 

Check your electrical connections and the vent in the cap. I had the same problem with an aftermarket pro street bike and when it died, I found the battery cable was loose.

 

I have had similar problems and both times, it was either the stator or the battery cable. Hope tone of this is your problem cause they are easiest and cheapest to fix.