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Electronic ignition Timing problem?

argonsagas

argonsagas

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GS1100GKE

Runs on regular/87 Octane fuel only.

Would run to 9000RPM easily, not too happy about being pushed past that.


Symptoms


Popping on deceleration...this came on rather quickly.

Increase in fuel consumption by about 25%


Bike used to start with only a sharp push of the start button, hot or cold.

It began taking a bit longer when cold. Much longer at or below freezing.




Treatment

Air cleaner checked.....OK, not due for cleaning, but replaced the stock cleaner with a new K & N free flow.


NGK B8ES Plugs all checked out medium to dark tan, electrodes OK, with little wear, but plug bodies are getting corroded on outside.

Replace with new NGK B8ES

Install new fuel filter.


New Symptoms



Bike starts OK, idles fine, pulls fairly well at low RPM, but will not tolerate open throttle.

Bogs badly above 3/4 throttle opening until over 5000RPM.

Max available RPM 8500.

Pull carbs and open them up.

Two have tiny bits in the pilot jet. Blow clean, check all through. All working fine.

Reassemble. Remount carbs on bike.

Check all fittings. All OK.



Bike starts well, still bogs in any gear when throttle is opened sharply, but will rev if allowed to run up slowly. On medium throttle, it pulls OK under 5000, but power curve is not as good as it was before.

At 5500/6000 at full throttle it changes personality....from there it revs very strongly to 10500 in 2,3, and I did not take it above 9000 in 4. Never saw 10500 before, and it never ran this well above 6000.

Gas mileage is still down, but not as bad as it was.

15 litres (4 US Gal) for 205km /125 miles.



Pull plugs.

All are the same.

Centre electrode is clean white, looks like brand new and unused, has acquired no particles or any marking. Farther down the insulator ...roughly even with the rim of the body... a soft black covering begins. (Brushes away easily with wire brush)

Body of plug, outer edge/rim has the same soft black covering. Side electrode is clean at the tip, but also has a soft black coat near the base/body.

Found a small hole in left side exhaust pipe (about 1/4 inch), just ahead of the muffler.

Nothing done about that yet.

There is obviously no fuel flow problem, as it pulls so very strongly at high RPM.

Fluffy deposits on the plugs suggest a rich mixture, but the white tip suggests too hot a plug, or timing is off, probably advanced too much, which could also contribute to the improvement at higher RPM 's, but they could have benefitted from the improved air flow of the K & N filter.

The manual says nothing about adjusting electronic ignition timing. Could this be a rotor/pickup problem? Other than visual inspection,( which I have not yet done) what is the best way to check it?
 
Well Ron you certainly did a thorough job eliminating stuff...the only things I could add would be the mechanical timing advance (I don't think your 84 has one) getting sticky,a loose rotor( I don't think the air gap is critical,as long as it's not hitting a pickup coil), maybe a ripped carb diaghram?(CVs right?) I'm pretty sure the popping on deceleration would be from the hole in the header....but it could also be from the gunk in the pilot jets....if you hadn't mentioned cleaning them, they would have been my first choice for all the symptoms
 
Do a fuel flow check. disconnect the fuel line from the carbs and set petcock on prime and see if fuel comes out like a garden hose, then check main and res. by sucking on the vacum line and see if it flows too. If you have a external filter check it the same way. Sounds like it's running out of fuel to me. If the plugs are white after running then it's running to lean.

Jake
 
Simple check here is when you are riding and the bike boggs turn the choke on and see if the problem goes away if it does then it's a lean condition.
 
Simple check here is when you are riding and the bike boggs turn the choke on and see if the problem goes away if it does then it's a lean condition.
 
Dave, I checked the diaphragms thoroughly, then sprayed them lightly with silicone before reassembling. No splits, no holes, and all flex easily.
After chemical cleaning, (spray carb cleaner..Gunk) I ran wet 1500 grit paper lightly on the needle, main body and slide and dried everything. All slides move easily.


Jake. I had tried the choke...bike did not like that at any RPM or throttle position.

I did not check the fuel flow, as I was certain it is good as the engine pulls so strongly at high RPMs...better now than it has ever done, and it is using 25 % more fuel than it was using last summer when it was running fine.

I checked for overflow, but found nothing.

The bogging is temporary....lasts about a second, sometimes two, when the throttle is pulled open. It doesn't matter if this is done at 2000 or 4000 RPM. A quick downshift to pass in traffic and I get a momentary pause/bog, then RPM's rise, and power keeps coming on, but not as well as it should. Then it clears at 5500/6000 and screams from there.

That makes it look like jetting, but the plug conditions are a concern as there appears to be limited burn, with the plug tip being clean, and the body black, suggesting incomplete burning of fuel.


I considered that the plug was too hot, but the plug type and heat range is unchanged, just new ones of the same make and series installed.

A lean condition in the fuel would give a white tip, but the black, sooty, substance led me to think of the timing being off, and likely advanced, due to the improved high end performance, with more RPMs than it has seen before.

The new air filter, with cleaner air flow, would also contribute to the higher RPMs, and could lead to a leaner mixture, so I will pull the K & N filter, clean the old one, (which is in very good condition) and put it back in, and see what difference that makes.

Before doing that, I will take the bike out for a short run, as I opened up all the mixture screws a quarter turn before putting the bike away last night.

None of this answers why the fuel consumption went up so quickly, (about 20/25%) and it did that before I made any adjustments or changed anything.

I have to take the car today, and I don't yet know if I will get to ride on the weekend.



Thanks for the replies.
 
Maybe a bad tank of gas?

Are all the plugs in the same condition.

Take a timing light and check all four leads one at a time and watch the firing, maybe a bad lead?

check wiring, fuses, key switch and kill switch.

If you got good fuel and fuel flow and the carbs are clean and the floats are set right and the jets are right and no vacum leak. Then it's timing or ignition problem.

Sounds like a simple problem but they are the hardest to find. I use to say 98 percent electrical probelems and 2 percent carbs problems.
 
possibly the electronic ignition is staying at full advance and not retarding (Getting Retarded?)when the rpms come down? I'm just throwing things out there.... fuel leaking through the vacuum pull off for petcock?
 
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