has anyone messed with improving the ignition systems on these old f2/f3s? I see a lot of people talking about weak spark and my f2 current has super weak spark even though it passes every test in the manual...

Im wanting to improve the ignition system to it sparks way hotter but am kind of stumped i have tried to cop conversion with little luck so far but i can keep trying if i dont have any new leads. I would really like to swap to new coils with better connections whether thats cop or standard coils with better spark plug wire connections and plugs..

thoughts? thanks

 

How do you know you have weak spark?
What numbers have you measured that points towards weak spark?

 

its visually weak but ive tested everything in the manual listed for the ignition system from the icm to coils plug wires ive gapped new plugs tested ground battery tested the pick up and all switches. in general ive seen many people complain of the same issue on both f2 and f3s which are the same ignition systems. i actually rewired the icm to coil wires adding weatherpak connectors using slightly heavier gauge wire because the stock harness has a resistance that was slightly above the specs recommended in the manual which did bring it within spec but still no signifigant change in the spark

visually looking at the spark and comparing it to my other bike which is a fuel injected 97 zx6r running a microsquirt ecu and a quad spark with gsxr 750 coils the spark produced on the zx6r is fatter and visually looks much much stronger compared to the weak looking thin spark on my cbr.

in general it would make the bike more reliable and easier to reduce possible future problems with better connections that are more secure and less exposed to corrosion, and stronger spark even if it doesnt produce any significant power increases would be a positive change to the bike and wouldnt hurt anything

 

Primary factors affecting spark energy is:

- charging voltage at coils
- inductance capacity of coils
- dwell time

Figure out what these values are for stock system.
Compare them to values from MS bike. How do they differ?
Then modify to improve.

 

im getting over 12v at the coils, and shouldnt the dwell be set by the icm so thats not adjustable so the only change would be from changing the inductance capacity of the coils?

either that or completely changing the system, which im thinking i would have to consider primary and secondary resistance to not cause issues with the stock icm

reason im suspecting ignition issues is i can confirm compression timing and fuel, i can confirm i have spark but its very weak, i went through the tests in the book and tested the battery and R/R but still have the same problem, every now and again it seems like it wants to start up but then it wont and eventually doesnt sound like it wants to again. i then check the spark and it seems even weaker or non existent like it comes and goes but no wiring has changed and ill even take a break to recharge the battery

 

Charging-voltage makes HUGE different in coil-charging. At 12.1v, there's significantly less charge at high-RPMs than 14v. Measure actual coil-charging voltage between CBR and MS.

Most are smart-coils that have built-in dwell control because they are powered full-time. Then ICM just triggers spark by grounding coil. Find specs for CBR coils and compare to one used on MS bike.

 

that makes sense, but shouldnt there still be a strong spark, at least strong enough to start and idle, when the bike is cold and is being started for the first time that day or for the first time in a few days? these cbrs run off ~12.5v so i would imagine that a fully charged 12v battery would be enough to give a cold start and produce good enough spark to start easily.

just assuming i take my eyes off of trying to improve the ignition system by swapping systems or coils, what would be the appropriate road to start down in order to get the system back to how it should be given that ive diagnosed what the manual recommends, that includes swapping to known good coils and known good icm's

i previously started a thread with the same issue and went through everything that was tested and the results there and i repeated the tests multiple times but was not able to get the bake started again. i can try to find that post and the results.

but i have an accessory tank with fresh supreme gas to eliminate the petcock, new spark plugs, have confirmed that it has compression no its not perfect compression but its easily enough that it should run and pretty consistent across all cyclinders, timing has not been altered since the last time it ran and drove which it did for years without issues, carbs were freshly cleaned and has the same balance as it did when it last ran which ran really well. the other day i sprayed a little starting fluid and it sounded like it wanted to start telling me maybe it was a fuel issue but when i did it again or tried to start again with both gas starting fluid it didnt sound like it wanted to start at all, i even placed a tiny bit of gas directly into the ports and even gave a small squirt of starting fluid, so i know for a fact that the cylinders were getting gas

so it had compression timing fuel and air only thing left is spark

 

Is there difference between choke OFF and choke FULL?

 

doesnt make a difference, i even sprayed the starting fluid into the carbs with the throttle fully open so i know i got the starting fluid to the valves