2 and 3 intermittently dying

Im having a really hard time diagnosing my bikes problem. The #1 and 4 cylinders always run perfectly and the bike always starts on the first kick. However the #3 cylinder will not run at all and I cant really tell but it seems like the #2 cylinder is either running intermittently or not running at all. Carbs and air filters are definitely clean and working. No vacuum leaks, new battery, no exhaust leaks. I checked both coils and the resistances were within spec (slightly high, primary was about 5 ohms). Both coils are only getting about 9.2V because of bad wiring which ive been meaning to replace, but ive checked all 4 spark plug wires with an extra plug while the bike is running and all 4 plugs have a good constant spark that could jump a .5" gap to the engine. What am I missing here? The #3 cylinder plug was black and wet, the #2 was slightly less black but still wet.

ok what bike

make?
model?
size?
year?
points?
dyna-s?

Right- sorry!

1979 KZ650, dyna s ignition, 4-1 vance and hines exhaust with pod filters, mikuni VM24SS carbs with accelerator pump

ok,

so we have two coils. 1 and 4 for one coil and 2 and 3 for the other. Sounds like you are having no spark from one of the coils.

The dyna-s will have two power wires that feed both coils.Do you have both sides of the dyna-s going to power?

I think so but the previous owner installed it so i will check. But the thing is the 2 and 3 cylinders both have spark. I fired up the engine, pulled the #3 plug wire and plugged in an extra spark plug i had lying around and grounded that against the engine and it produced a constant steady spark. Repeated those steps for the #2 cylinder and it too had spark. This is why im confused.

could the coil be grounding out on the frame.....this is a very common problem with dyna coils. Please re-check the power wires and the crimp on connectors.

There are several forum members that forgot more than I know......just be patient, someone will figure it out.......could take a while.

Here is the tech download page for your Dyna-s.......ck this out for info, might help you.

www.dynaonline.com/skins/downloads/Default.aspx

No the wires are definitely OK, ive double checked. Also they are not dyna coils, they appear to be the original TEC coils.

Ok,

on my bike.....I cant use stock coils with a dyna-s.

The stock coils on a kz1000 are rated 2.8 ohms and the dyna-s requires that you use 3.0 ohms. It dosent sound like a big difference but it is.

This might be a problem. Do you know 100% you can use the stock coils with a dyna-s ignition?

I'm really not sure, i'll try to find out. But the 1 and 4 coil seems to be working fine so I want to say yes. My multimeter reads 5.2 ohms across the primary coil.. but maybe the multi is bad. Also like I said im only getting 9.2v at both coils, but i still consistently have spark on all 4 cylinders. Its very strange.

who8myrice wrote: I'm really not sure, i'll try to find out. But the 1 and 4 coil seems to be working fine so I want to say yes. My multimeter reads 5.2 ohms across the primary coil.. but maybe the multi is bad. Also like I said im only getting 9.2v at both coils, but i still consistently have spark on all 4 cylinders. Its very strange.

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I just looked on Dyna website and found the DS2-2. This is the dyna-s for your bike. It said you need to use DC1-1 which are the 3 ohm coils.

you might have some valves hanging open (no clearance) on header side

what compression numbers look like on them cylinders?