#1 cylinder is eating spark plugs

I just realized that on my z650b1, i have been riding on only 3 cylinders ever since i finished the rebuild. I replaced the spark plug (in #1 cylinder) and was amazed at the power increase, but the next day it fouled again. I am assuming that its because of a weak spark? The coils are original and probably not in the best of shape. Does this sounds right?

If so, I was thinking to buy new Dyna coils. I'm running the original points setup, and the original coils are 4 ohms (I think), but Dyna only sells 3 and 5 ohm coils. What do you recommend? Thanks always.

Is it oil fouling? if so, leaking valve stem seals can do this. How's compression? Spark energy good(hot fat spark)?

Tried changing ports on the ignition coil that runs #1 and #4? Good sparkplug caps? Ignition wires/cables/leads good?

compression is fine. You said that I should try switching the #1 and #4 plug wires? Is that ok to do? I can say however, that the condition of the coils and wires are not great. I have a spark in all four cylinders, but they are by no means big and fat. I'm planning to buy new coils anyways, but wasn't sure if I had any other problems. I was also thinking that it may be due to bad float valves.

Exactly what plugs are you running? I had a problem years ago woth my KZ650, oddly enough with cyl #1, that turned out to be a result of running the wrong heat range plug. Ed

Rebuilding the engine and not making sure the spark is strong? Get an ohm meter and check the juice to the coils and well, I guess if the wires are old. That makes a big difference too. I replaced my wires in my car and even though they looked clean and pliable made a huge difference with the wires being changed out got more power and acceleration. I would opt for new coils and an ignition plate but I just hate those adjustable points. My .02 nothing more. If the coils are bad then you would have two plugs fouling if one of them were bad.

I dont know how to tell if the the plugs are fouling due to oil or not. I never tested the coils because i planned on replacing them anyways. The wires are definitely in bad shape, the condition of the coils is not the question. I am hoping that the reason that the spark plug fouled is because of the plug wires. My friend also seems to think that its because the cylinder is getting too much gas due to a bad float valve.

If someone can help out, what aftermarket coils do you recommend? Should i go with the Dyno 3ohm coils?

Step 1 is to ensure you are running the correct plugs. What are you running? Ed

Dyna Green 3 ohm coils is what fits your bike. You can spray some water on each exhaust pipe right when it starts up and see which cylinders get hot and sizzle the water off, you can tell the dead cylinder this way in the future so you are not riding on three cylinders. As asked before what plugs ya runnin?

sorry, i had to go check. I am all brand new NGK B7ES. I usually just check the pipes by touching them real quickly. Last time when i replaced my #1 plug, I started the engine (cold start) and checked to make sure that all cylinders were firing. They were. I drove 5 minutes and checked again. #1 was cold.

A lot of good advice there especially this one...
"You said that I should try switching the #1 and #4 plug wires? Is that ok to do? "

Reasoning.... If the sparky plug problem follows from #1 to # 4, then your problem is not necessarily the coil itself but the plug wire/plug cap.

If you review your wiring diagram you'll find that cylinder 1 & 4 share the same coil primary and secondary outputs... Since only one of the plugs out of that coil is giving you issues chances are it's not necessarily the coil...

Since they share the same point and condenser components, somewhat eliminates that as well...

As for Dyna coils, nice stuff there no doubt... If your OEM is cracked, brittle, spark plug wires hard etc.... May be time to do exactly as you mentioned, replace with Dyna or OEM coils for that matter....

OMR

you gotta loose bore or valve seal...see if it will fix by running a hotter plug...not forever just try one in that cyl for a day or so...if you run a b8es normally try a b7es...see if it still fouls it...did you re-ring it ..or just rebuild the bike itself???

B7ES - good. Swap wires & caps 1 & 4 as suggested to see if problem persists on #1 cylinder. If is does, it probably is fuel not spark related. If the problem moves, it's time to take a close look at the wire and spark plug cap. Ed