84- 550 es, wont idle when hot

[amartina75]

i checked the spark across all four cylinders it was the same and jumped a 1/2 in gap in a spark tester. if it can jump a gap that big I wouldn't call it weak. I'm going to put new plugs in it one heat range hotter and gap them to the wider spec and see what happens. also going to try turning the pilot mixture screws in 1/2 turn.

[amartina75]

ok i put new plugs in it one heat range hotter and set the mixture screwes at 2 turns out from 2 1/2. went out and ran it hard did not let it idle, pulled the plugs and they were a white/grey. then i replaced the plugs and tank. let the bike sit and idle. it idled for a little over 10 min then started to pick up rpm's i backed off the idle knob it ran for a couple of min then started to labor a little and died. any thoughts? how long is too long for a bike to sit idle? will any bike die on a hot day after 10 min? am i running too lean now? was the combination of hotter plugs and turning the mix screws in 1/2 turn too much?

[DV8]

The choke on these bikes isn't like your standard choke, they do not block airflow so much as they just add more fuel.

Could be contributing to your plug issue, if you are running with the choke pulled some....

[KEITH KRAUSE]

You don't say at what rpm the idle screw is adjusted at. Your bike should idle well at 1,000 to 1,100 rpm. Have you tried that specific range?
As for the mixture screws, they're supposed to be adjusted using the highest rpm method. If the bike won't idle well when at normal operating temp, try adjusting the mixture screws. On many models, straight from the factory, the mixture screws can be as little as 1/2 turn out, so there's a chance yours are simply too far out and causing a rich mixture which would worsen as it warms up.
I would go back to the correct/standars sparkplugs.
I assume the bike is stock and the air filter is clean and the correct type and all air box seals are good.

[amartina75]

i did have the idle set at 1100 rpm's when fully warmed up the problem is it wont stay there when i really get it hot after riding it hard. the plugs look good now. tan in color no black, i ended up turning the pilot screws back out to 2 1/2, after riding and checking them several times. but the problem is still there. I am now thinking i have i have a bad wire or wires somewhere. because i think the spark is degrading after everything gets hot. when i first got the bike i checked out the wire connections started pulling back tape and noticed a bad ground wire the insulation was melted. i thought i did a good job replacing the wire but i think, now that some other wires were damaged, although not visible. i think i have an excessive resistance problem, even though my electrical components are good the wiring is not.

[KEITH KRAUSE]

Yes, it could be poor electrical connections/resistance related. Have you tried testing the coils resistance at both primary and secondary sides? Have you inspected the plug caps? How does the regulator test at various rpm's? All connectors and the battery must be in good shape to do the tests.
If all are OK, there's a couple more things to check.
Be sure the venting is clear. Gas cap and any float bowl vent lines or the float chamber vent passages themselves. Heat generally aggravates a poor venting problem.
I would also verify the entire pilot circuit is clean and the float levels are correct. Dirty air jets, at the filter side of carb body entrance, could be varnished up a little and creating a "rich" problem once hot and at idle. Poorly operating choke circuit could cause your problem. Takes only one carb to cause this problem.