Ignition


Magnet21
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Re: Ignition

Post by Magnet21 »

Couldn't keep my hands off the damned thing......didn't fix it but got further into the puzzle. I started by substituting a known good battery for the one that was in it to eliminate that as a cause. While switching those out I found a loose connector in the wiring compartment and butt spliced those wires together. Had the tank off and there is no vacuum rig on it for the petcock. The only line off the petcock disappears into the #1 carb area. It gave a good cold start with no extended grinding on the starter like before. Once off choke, it blipped right through the 3000 RPM rough spot. I had high hopes! But never fear the gremlins persisted. As it warmed all the way up, the rough spot reared it's ugly head and if left idling, it would stumble and die. It would start right back up as described before but would die after a minute or two. So we eliminated the vacuum petcock thing, battery is known good and symptoms reappear with engine warmed up all the way. It still runs like gangbusters above and below the rough spot so I am leaning toward something electrical breaking down when it heats up maybe? It is still going to the shop. :x Thanks for the support out there!

EMS
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Re: Ignition

Post by EMS »

Coming back to my earlier post: The correct carbs for your bike have two fuel inlets from the vacuum valve, one between carb 1 and 2 and another one between 5 and 6.
If your has only one, someone has either jury-rigged the second inlet or changed the carbs to a 1979 version. Check the number stamped on the left side of the No 1 carb.
It should read VB62A....If it does, check what they did to the fuel inlet between 5 and 6.


7623

Magnet21
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Re: Ignition

Post by Magnet21 »

Thanks! Will attend to that tonight after work....

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Re: Ignition

Post by Magnet21 »

For EMS:
The fuel line goes into a sort of one pipe manifold that feeds all 6 carbs. The numbers you wanted are: "60AQKt" on a small boss on the carb body and there is a larger sized embossed above the boss that says "VB". Hope that is not bad news.

daves79x
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Re: Ignition

Post by daves79x »

Those are VB60 carbs you have. They are '79 model carbs. Single inlet as you have described. '79 carbs work well on all years, but your original VB62 carbs have been replaced. I have 2 or 3 spare sets of VB62 carbs if you must have the original ones. This fact also would have had a bearing on what Dynojet kit you used. If whoever did the work ordered a kit for the '80 carbs, they are way wrong for the VB60. Might explain a couple of things. The jetting is altogether different. Someone that know needs to look into your carbs.

Dave

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Re: Ignition

Post by Magnet21 »

I will pass on the VB62's. Would just like to get the ones on it to act right. The kit installed is listed as fitting 80-82 models.

daves79x
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Re: Ignition

Post by daves79x »

Totally wrong kit for your carbs. It needs to come out and the stock jetting put back in. You almost certainly have some plugged low-speed circuitry.

Dave

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Re: Ignition

Post by Magnet21 »

So if we pull these carbs out and redo the jetting to what should be in 1979 models, we should get a better running engine?

daves79x
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Re: Ignition

Post by daves79x »

And make sure all passages are clean and other functions up to snuff. Were these carbs separated completely last time and new joint o-rings installed?

Dave

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Re: Ignition

Post by Magnet21 »

As far as I know, yes to the separated completely and new O-rings installed, float levels checked, etc.
I saw them off the bike and removed from the intake assembly that connects them to the head
Tech stated the inside of the carbs were very clean when disassembled. New carb boots were installed
when the DynoJet kit was put in.

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Re: Ignition

Post by EMS »

...and so we come to the bottom of it all! 8)

Magnet21
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Re: Ignition

Post by Magnet21 »

I sure hope so!

daves79x
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Re: Ignition

Post by daves79x »

The pressed-in slow jets should have been pulled and cleaned also, put probably were not. They are pressed-in and need tapped to pull them. Also, as I said before, I hope you still have all the stock stuff. The aftermarket parts available are horrid. Especially the jet needles. Let me know if you need help.

Dave

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herdygerdy
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Re: Ignition

Post by herdygerdy »

A sure fire way to measure the voltage drop at the coils is to have the positive lead from your mulitmeter on battery positive and the negative lead from your multimeter to the positive black/white ire on the coils (it's the one that is jumpered between all three coils). And of course with ignition and kill switch on.

A long time ago, the highly respected Mike Nixon taught me that voltage is a measure of electrical pressure and the when measuring volts, the multimeter simply measures the pressure differential between the positive and negative poles.

With zero voltage drop at the coils, your meter should read zero volts. But if a number appears on the meter, then right there is the measure of the voltage drop between battery and coils.

On my 78 TS CBX IIRC, I had about 3 volts of drop. Fixing that with an ignition coil relay made a HUGE improvement in general running, more mid range and vastly improved starting, esp. when left standing, sometime for weeks at a time (Sob!)

Next thing on my list is to ensure all 3 pulsers are set exactly at 120 degrees on the backing plate and the static timing on all 3 pairs of cylinders is spot on.

You would save yourself a LOT of angst and let Dave help you out on this for sure. Time and money probably much better spent than on the "crap shoot" with your local shop....

My two South Pacific pesos worth and keep us posted on how you get on. As they say in the CBX classics "Ditch the Dyna!"

Magnet21
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Re: Ignition

Post by Magnet21 »

Thanks to all who helped! We are busy rounding up parts to put the carbs right and will report the outcome

Jim

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