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Replaced ignition parts still weak spark.

  • Thread starter Thread starter APmech
  • Start date Start date
A

APmech

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After 5 miles I gradually lost power down to 20ish mph stopped and the right two cylinders were cold. Played with the plug wires, pulled them off individually with no rpm drop. No drop when both were off. After sitting along side the road for a bit I started it up again and had full power again. I pulled 3 and 4 for wires off and had an rpm drop, although through the wires I could feel the spark. I was going to limp it home and stop when needed to let what I thought was the coils cool off. But on the first go I forgot to turn the fuel on and thought it was just senseless abuse to keep going and got a ride.
At home I checked the power at the coils and I had 12 volts. I did do resistance checks but it's been awhile so I don't remember what they were. It doesn't matter because I ordered new dyna coils, and since in for a penny in for a pound I also got new wires, points, and condenser. All from z1 enterprises.
Put all the parts on as I thought they should be, and set the point gap.
It has never had confidence inspiring spark. Now it still has small weak yellow spark. It will start on the choke but it has to be feathered off. The throttle is very sensitive it opened to quickly it dies, and it gains revs like snail. Also has a random backfire ish pop every now and then.
 
"It doesn't matter"

lots of of stuff matters here......is this a recent problem or something that you inherited? Sounds like a two for....electrical and carbs. The stock ignition coils are very durable and unlikely to go bad. Your money would have been better spent on a dyna electronic ignition to replace the points. If the new dyna coils are 3 ohm variety , your points won't be happy long.
Run down what have you done maintenance wise on carbs.
 
Doesn't matter since I have new coils. What makes 3ohm from dyna different when 3 ohm was written on the old coils? The carbs are fresh and had miles on them this year. I kept the points because I couldn't find a clear answer if the bit to replace them was all that was needed. I did keep the plugs I was running.
 
If I recall correctly, the stock coils on point/condenser setup were 5 ohm primary. The later electronic ones used 4 ohm coils.
 
When out and started it left two cylinders are dead cold. Pull the plugs off and no drop. Still getting shocked though.
Bummer on the coil ohms it was 3300 that it said and tested at 3ohms
Also it was the first time its ever started buy kicking it.
 
Well, you are convincing me that it's a carb (or fuel) issue.....but it's hot here , so what do you think?
 
I was going to use my color tune to maybe see what's going on but I lost the little stick. Then was going to pull the plugs and check them but in pulling off the left 2 i didn't like the way they felt. Then I put them back on and the right plugs . It was better for throttle response and they were warmer. Rest the air screws to base line, two out, then did the fuel screws under the carbs to 1 1/2 out. Better ish. Right 2 still run colder. The vacuum gauges were 3, 10, 8,9. Checked a plug out while running spark was purple. Since the vacuum was low shot all the backs of the carbs with carb and choke clear with no change. I guess I'll pull the carbs but they were clean and maybe get non Taiwan parts.
 
Since you were tugging on plug wires, doublecheck that they are on correct cylinders - this is easy to mess up. But sure seems that you need to clean carbs..skip rebuild kits, the stock metal parts should be fine after cleanup. But get new carb orings from a member here.. Might want to consider carb boot o-rings at head interface while you're having carb fun.

http://cycleorings.com/VMkit.html
 
It is interesting that you lose two cylinders at a time. If it were 1&4 or 2&3, I would suspect ignition, but you say you lost 3&4. Later, you said you lost 1&2. I would have you check to verify that you do have the wires on the correct plugs. The left coil should be firing cylinders 1&4, the right coil should be firing cylinders 2&3, unless someone has swapped the coil positions (it happened to me).

The issue with the coil resistance is that lower-resistance coils will allow more current to flow through them. Although more current does give a better magnetic field and a hotter spark, it also contributes to burning the points. As mentioned, the bikes with points had coils that were specified at 4-6Ω, bikes with electronic ignitions were specified at 3-5Ω. Does not sound like much of a difference, but the points definitely have a shorter life with higher-current (low resistance) coils.

Also, were the coils you removed STOCK coils? I don't remember seeing any that had the resistance printed on them, so it's possible that they were replacements. Based on the history and reputation of "previous owners", I usually hesitate to replace an item with what it already there. I will check to see if that is actually correct, then replace with what SHOULD be there.

.
 
The old coils were probably correct. I tested them at 3ohms. And it said on the top 3300 Suzuki. I pulled them off about a week before I ordered parts on lunch at work so it was a memory thing. The plugs have been hooked up correctly. Right now it seems like it's back to normal in the garage I haven't ridden it to feel it. I also need to charge the battery I had the harness plugs disconnected and forget to turn the key off when I was checking stuff a couple weeks ago.
The plugs are loaded with soot as well. So I think I'm gonna order the carb kits from jp cycles since I wasn't super impressed with getting Chinese points from z1 and having to oval out the holes more to set the timing.
What should the fuel screw at the bottom of the carb be set to as a base line I've always struggled to find it.
What do you use for a timing light to set that, a regular automotive light or a mag sync light? The manual I have calls a part number but doesn't show it.
Would some hotter plugs help actually it burn the charge better?
I really want to take it to Road America at the end of the month and I'm getting cruched for time now. It's being a real problem child this year.
 
Last edited:
APmech said:
The plugs are loaded with soot as well. So I think I'm gonna order the carb kits from jp cycles ...
Click to expand...
Please, do NOT waste your money on carb kits. Just clean them properly, then re-assemble with an o-ring kit from cycleorings.com. If you don't feel comfortable doing them yourself, send them to Chuck Hahn or Chef1366 for a proper overhaul job.


APmech said:
What should the fuel screw at the bottom of the carb be set to as a base line I've always struggled to find it.
Click to expand...
That depends on your intake and exhaust systems. For a stock bike with original intake and exhaust, 5/8 to 3/4 turn will probably work. Start with the air screws (on the sides) at about 1 turn. When the bike is warm enough to run without "choke", you can slowly turn them out a bit, listening for best idle speed on each one. They might end up anywhere between 1 and 1 1/2 turns out.


APmech said:
What do you use for a timing light to set that, a regular automotive light or a mag sync light?
Click to expand...
A regular automotive one works just fine. A clamp-on version is really nice. Just clip it on the plug wire for #4 to check timing for 1&4, then move it to #3 to check 2&3.


APmech said:
Would some hotter plugs help actually it burn the charge better?
Click to expand...
No. "Hotter" plugs produce exactly the same spark as any other plug. The reason they are know as "hotter" plugs is because they have a longer internal path for heat sink. That means that they stay hot from combustion longer. A "colder" plug has a shorter path (the ceramic 'nose' in the center) to a heat sink, so it stays cooler. Changing the heat range to something other than what is specified is only a Band-Aid. In your case, a hotter plug might burn off the soot, but why not fix what's causing the soot, instead? That would either be too rich a mixture at the carbs, bad oil seals, bad seating of the valves, etc.

.
 
If you have inherited someone's project, and don't really know its history,beware of creativity. Some guys will drill out mains,etc. . So inspect the jets and screws looking for mikuni markings . Aftermarket carb parts are iffy and make it harder to get bike running well. What does this bike have for airfilter intake?
 
I've owned it for 2 years I did the carbs so no drilled stuff. It's all stock.
 
When you got the 12 V at the coils were the supply plugs open?
If those plugs are corroded that 12V will fall off quick as soon as current starts flowing.
 
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