Ignition


Magnet21
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Ignition

Post by Magnet21 »

My 80 SS has suffered for some time with really awful cold starting, like sometimes grinding on it to where battery is starting to drop off. Then it sometimes smokes after finally catching and runs OK on half choke until warmed. Does not smoke when warm. I had a dynojet kit installed hoping to get rid of a bumbling sorta flat spot it has at 3-3800 rpm. Runs OK below that and OK above that. The kit did not improve the flat spot much and the hard starting is still there when cold.

Wondering about the low voltage to the coils I have read about on here caused by aging components upstream from the coils.....is that a logical next step? It's got gas, no problem with air supply so spark ought to be next.........I guess. :handgestures-fingerscrossed:

Cheers.
Last edited by Magnet21 on Mon Jun 25, 2018 1:25 pm, edited 1 time in total.

Rick Pope
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Re: Ignition

Post by Rick Pope »

It would be easy enough to test your theory by running a jumper from the battery to the coils If that fixes it, you've found the problem.

The other thing to check is whether there is gas in the float bowls. If you still have the vacuum shut-off, it takes a bit of cranking to fill the bowls. There are tricks to get around that without disabling the vacuum valve.

What air filter are you running? Hopefully stock......
Rick Pope
Either garage is too small or we have too many bikes. Or Momma's car needs to go outside.

Dynamohum
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Re: Ignition

Post by Dynamohum »

How often do you normally start it?

daves79x
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Re: Ignition

Post by daves79x »

As Rick said, check the voltage at the coils (low side) with the key on and compare it to actual battery voltage. If it's more than a volt lower, you have a problem in the circuitry, which is quite circuitous, to the coils. There is a ready-made relay set-up made that give full battery voltage to the coils and does improve starting and running.

But I would suspect the health of your carbs as a potential culprit. The accelerator pump plays an important role in starting. A functional pump will provide the extra charge of fuel you need to get the bike started. This assumes your vacuum valve is functional, or bypassed. If functional, blow into the vent hose for the valve for a few seconds to fill the bowls with fresh gas. See if starting improves with just that. If it does, then you might have a bad vacuum valve. In any case, once you verify you have gas in the bowls, 'pump' the throttle a dozen times or more to actuate the accelerator pump. This will put a good charge of fuel in the cylinders and then turn the key on and try it. It should start pretty quickly and on all cylinders.

These are notorious hard starters after sitting a few days without the carbs drained. The above will help.

Dave

Magnet21
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Re: Ignition

Post by Magnet21 »

All:
It is running a stock aircleaner. No Vacuum shutoff on this one. I try to run it every 2-3 weeks. It stays on a trickle charger. It has gas stabilizer and anti ethanol stuff in it. Tried the 10-12 pumps on the throttle and it touched right off. Still has the stumbles in the 3000 RPM range but now it doesn't do it everytime like before...so more to the mystery mix. It still goes dead at idle when all the way warmed up. It is going to get some shop time for all this as I am unsure of what else to look for. It seems to be both carb and ignition/electrical related and that is most likely beyond my capabilities and equipment.

Thanks so much to all that answered and I will keep you posted on what it might do next.....I am dying to get it out and ride, but don't trust it with these maladies :violin:

daves79x
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Re: Ignition

Post by daves79x »

You need a complete carb overhaul, I think.

Dave

EMS
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Re: Ignition

Post by EMS »

Something else you may want to check: The vacuum valve on the CBX-A has two (2) fuel inlet lines to the carbs (unlike the late model change and retrofit for the CBX-Z). The petcock has only one outlet line. So, if someone took the vacuum valve out, as you say, they must have rigged something in the inlet lines between petcock and carbs, like a t -joint. Make sure you don't have a fuel starvation issue there.

Magnet21
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Re: Ignition

Post by Magnet21 »

Will check on that, sounds like I will need to pull the tank for access.

Dynamohum
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Re: Ignition

Post by Dynamohum »

Have you tried adjusting the idle screw?

Larry Zimmer
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Re: Ignition

Post by Larry Zimmer »

Primary cause of low voltage to the coils would be corrosion at any/all connections between the battery and the coils. Meaning ALL connections. Includes such things as the goes-into and comes-out-of the ignition switch, etc. Doesn't take much at just a few connections to drop a couple volts. Your 3k flat spot -- I'm with Dave on the carbs. Unless, by slim chance, you have 6-1 exhaust on your bike. Having said that, I've always noticed a slight 'flat' in the 3k to 3.5k range. On several other bikes, too.

The 10 - 12 pumps to get it to start has me wondering if the choke is operating. Typically, that would bring on Noah's flood. And, not idling when warm is likely either the idle screw adjust; OR, as Dave said, needing a good 'take 'em apart' carb clean.
Larry Zimmer
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Magnet21
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Re: Ignition

Post by Magnet21 »

Larry, Dave and Dynamohum;
The carbs were taken off the bike and gone through last summer. This was done before the DynoJet kit was installed. I will check all the connectors as Larry suggested. I have adjusted the idle screw to run at 1100 when warmed. It will eventually stumble a bit and then quit if you leave it idling at that speed. It likes 14-1500RPM better and only stumbles, does not quit. I can't tell if that is a fuel or ignition issue. It fires right back up without a problem. I am also thinking of load testing the battery to eliminate that being part of the problem. It has a high charge rate of just over 14.5 volts at 2500 RPM and a digital voltmeter across the battery poles at the same time agrees with that. It has the "euro" alternator that Tim's sells installed.

I can recall its attempt to strand me a year or two back. It would not idle during stops so it had to kept revved to continue running and finally it quit all together (great fun in DC traffic). I pulled the right panel that covers all the electrical stuff and found a melted connector on one of the thicker wires. Had enough stuff and my McGiver knife with me and effected a connector repair roadside. Pushed to start it and it got me home OK. Battery was back up by then. No repeats on that scenario since then. I replaced the 30 amp main fuse strip with an inline 30 amp fuse holder some time back. Have not found any wires that are hot to the touch in that electrical compartment.

The choke cable was replaced when the DynoJet kit was put in as the original had been kinked. It seems to check OK for operation. If I start it cold and warm it a bit then turn off the choke and rev it slowly up to where it starts to stumble, slow application of the choke will zip it right through that rough running patch. I am thinking that indicates a fuel problem of some sort. Plan at this point is to pour $$ on it until well as I am outta ideas and abilities. Oh, it has the twin mufflers with 3 pipes running into each....

It just bothers me that more than one thing is causing this problem.

Larry Zimmer
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Re: Ignition

Post by Larry Zimmer »

The 'melted' connector is a definite sign of resistance in those connectors. The 14.5 charging voltage is good. Might be just a couple tenths high. Wouldn't think it would do any harm. The idle thing does seem to implicate idle circuit in the carbs. Dave can tell you more there! Good luck chasing these gremlins. And, they are gremlins!!
Larry Zimmer
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daves79x
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Re: Ignition

Post by daves79x »

You likely compounded your problem with the Dyno-Jet kit. With the stock airbox, all you did was decrease your gas mileage. The carbs didn't get clean during the rebuild. The carbs need done properly, all the stock components need reinstalled - hope you still have them. That is the problem. If you can't find someone to address the carbs, I can help you.

You can't flood these things, choke operating properly or not.

You electrical problems are very common and glad yo got them addressed. However, they have nothing to do with your current problem.

Dave

Magnet21
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Re: Ignition

Post by Magnet21 »

Thanks to all who replied and advised. Will post shop results when I get the beast in there.....kinda tired of fooling with it especially when you think you have it fixed and then it up an does something worse or new.....I did a quick critical path on getting it under control and it had a lot of dead ends so it is shop bound when I get the time to get it there.

steve murdoch icoa #5322
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Re: Ignition

Post by steve murdoch icoa #5322 »

Magnet, i certainly get the frustration and wanting someone more capable to get your bike running properly.
Not knowing your shop, the best advice i can give is to get your shop to send the carbs out to one of the experts aka daves79x.

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