Ignitor troubleshooting

[GaryS-NJ]

I'm working on a '95 Kat 750 California bike I bought not running. After going through the carbs, I think I have an ignite issue because I always have one cold cylinder and the dead cylinder moves around. It doesn't move around randomly but rather one cylinder will be dead for a while. I was chasing carb gremlins until tonight when the dead cylinder went from 1 to 2 (without touching #2 carb) and then #3 stopped firing. But the bike seems to rev fine (I never had one of these bikes and maybe it revs good on three cylinders or maybe the cylinder is coming in when I twist the throttle). As an aside, it is idling at 3000 rpm and now I'm thinking this also is the Ignitor (but if I push the throttle shafts down it will bring the idle down..) I can test the pickup but don't see how that could kill just one cylinder.. And the manual only shows a special tester for the ignitor.. I'm worried about buying eBay used because it might not work any better than mine.. Is this a typical ignitor failure mode? Lastly, any members here have a spare ignitor they would like to sell?

[GaryS-NJ]

Oh, and is there a range of years or models for ignitor that will fit my 1995??

[92xjunker]

The tester is beyond most riders wallets, I can say this, check each plug for spark with a spark tool (found at auto parks stores) if you have spark it's not the igniter. 88-95 box will fit but, you should match the model number as the timing program does change through the years. My thought is it's the carbs. Did you check the tank for rust and sediment?

[GaryS-NJ]

Thanks again.. And great point. I had used a spark checker before while battling carb issues and this last round after unpluggi,g those pilot holes, I've been using an inductive timing light to verify spark. The timing light was giving intermittant results which led me to re doing the coil high tension connections. With a waste spark ignition and only one pick up it is hard to believe the ignightor could drop one cylinder randomly without causing backfiring.. I did have an ignightor on my yam venture which lost one output and wouldn't advance... Ill try the spark tester today but how is it possible for a carb bank to not fire #1 and then without touching anything then have #1 come back and #3 drop out (#2 might have dropped again along the way). And the high idle is beyond me. Way back I attributed it to bent butterflies and then a leaking float oring

[92xjunker]

High idle could be a myriad of issues. Air leak in the intake systems, miss adjustment, throttle cable hanging up, choke sticking open, overly rich setup (use the drop down technique for the idle mixture). If you have crap floating around your carbs could be intermittently clogging up. Pre kats are not designed to run fuel filters, other issues will arise with them.

[GaryS-NJ]

Yes the fuel tank had rust but I washed it out and soaked in evaporust and rinsed with fuel... But most all of my testing is with the carbs fed with funnels through large gauge lines. I went through the pilots and found some partial clogs and now have it firing on all four. But with them close to balanced using a mercury guage, my idle is still way high like 3000 rpms. I verified my choke plungers all closed and also throttle cable slack and butterflies snapping closed during a bench sync (all butterflies covering 1/2 of the first orifice). Previously I dropped the float levels towards the lower limit (raising bowl fuel level) but taking carbs off I could see fuel wetting the bottom of intake manifolds so I brought the floats back up to 14.6 mm. Still no luck as the idle is hanging high. When I took off the carbs the mix screws were set at 2.5 turns out. Tomorrow ill bring them in to 2 turns but I thought pilot mix screws were generally set for highest idle. Scratching my head over here. And those pilot jets seem awfully small as I can't even put a high E electric guitar string through them. Also in my carb work I've been installing new float asst o rings each time (bought bags from grainger).