Help: Runs worse after timing

[jdvorchak]

Now that I re-read your original post I have to think you have a dead miss. Have you run a compression check to make sure have compression? The simple fact is that you need air, gas and a spark at the right time but that only applies to a healthy engine. For all you know one of the pistons has a hole in it or is missing entirely... Don't laugh.. I bought a CB900 once that only had 3 pistons and rods and it started and ran!

[groupus]

That would be interesting, although I did find all 4 when I changed both head gaskets. I remember doing a compression test when I was diagnosing a blown head gasket and I think I checked it after too.

Obviously something is wrong with the sequence of suck, squeeze, bang, blow

Fyi: Dyna is on Amazon prime for $133...

[groupus]

New update: I switched the entire points assembly from the other bike and reset it and the issue persists. So far I've ruled out the carbs, ignition, timing, resistor caps. I guess I'll get another set of spark plugs and swap some coil wires around. I'm running out of things to try. The thought that it could be a dead cylinder is a possibility, but everything did look fine when I had the heads off.

[CYBORG]

I'm still wondering if the advance unit is working. Have you checked it?

[jdvorchak]

In my mind you have not ruled out the carbs. If that header pipe is still colder than the others and you say you have compression and spark what else is left?

[Track T 2411]

In my mind you have not ruled out the carbs. If that header pipe is still colder than the others and you say you have compression and spark what else is left?

I agree with jdvorchak on this. 'One and done' on these carbs isn't always true, even for the most experienced wrenches. Not trying to knock your ability, just saying...

[Griffen]

I may have missed it but have you checked your coil and coil wires?

[groupus]

I can certainly never rule out the carbs, but they are definitely low on the list now. this is the 3rd time I've cleaned this particular set: once in-situ, once completely disassembled but without replacing anything, and finally a complete overhaul again with the Randakk master kit. Plus it did exactly the same thing with the 1100 carbs off of my good running '78 gl1000 which were also rebuilt probably 1000 miles ago. Plus, I've seen bikes run with some pretty haggard carbs. Again, not completely ruled out, but I'm 98.9% sure they are not it.

SOOOO here's the really interesting thing: if I hook up a timing light to the #3 lead, it flashes sporadically. All other cylinders flash fast and consistent. I replaced the spark plug, swapped the resistor caps, checked the valve clearances, and even swapped the coil wires (because it is a wasted spark system, you can swap the #1 and #3 wires with the #2 and #4 wires and it will fire the same). Still, #3 is always the dead one. If it were any one of those components, it would affect a different cylinder. This is crazy!

Now to steal some Coils! My poor naked bike is becoming a parts mule


Edit: Oh also, I did check and lube the advance do-hicky, seems fine. And if I pull the plug for #3 while it is running, it gets worse, so it is doing something, not completely dead.

[jdvorchak]

Ok I concede that it's not your carbs. so swapping the plug wires didn't help that leaves only the coils. Must have a bad tower on that coil to the #3 cylinder. Easy enough to test. Swap the plug wires side to side on coil. See if the problem doesn't move to #4.

[groupus]

The crazy thing is that I did swap the plug leads side to side - #2 and 4 on #1 and 3 cylinders - and it did exactly the same thing! That makes no sense to me. Yes, it should have transferred the issue to #4 if it was the coil. Finally, I did steal the Dyna coils from other bike and it ran better. Not perfect, but better. There is still some missi-ness in the strobe light on #3. but not nearly as bad as it was. My expert conclusion is that the cylinder is haunted and the whole bike needs an exorcism.

In other fun news, I went to ride it to work this morning. It fired right up, idled and took off fine, but then it stalled and would not restart. It's definitely haunted.

[salukispeed]

IF you are using an inductive timing light it is important to have the pickup/clamp oriented the correct way and since these are a waste spark system the direction the current passes through the cable is opposite. On my light I need to flip the clamp over to get it to flash reliably . It sounds odd but is true. The arrow on my clamp needs to point away from the plug on one side and towards the plug on the other.

[groupus]

The arrow on my clamp needs to point away from the plug on one side and towards the plug on the other.

That is very interesting and may explain what I am seeing. Either that or mild psychosis.

[salukispeed]

I have what I think is a quality light ( Snap On ) but it is finicky how the clamp is positioned. It is old 20 years

[Easter]

Bad plug maybe, How were you checking for spark?

[VintageMan77]

I am a fan off the C5 - take a hard look at Paul's set up before popping on a Dyna.