idle hunting below 1500 rpm

[Seaking]

After replacing a dead Key switch, dead starter circuit cutoff relay (aka side stand relay) and the starter relay (why not, everything is changed), I then had to change a dead pickup coil a week later. Before the bike died, it idled well, ran well and when it did, would start well, then the pickup coil died so that got replaced.. All went well, no extra parts left on the bench, nor missing any parts, bolts or screws..

 

The bike starts ok, choke not required. It will drive like a bat out of hell, making good smooth power throughout the gears, speeds and powerband..

 

But it does not idle nice.. If I set it at 1500 rpm it will idle smoothly, albeit high.. and start reasonably well.. If I set idle at 1000 or so, starts are a little wonky sounding..

 

If I turn the idle adjust screw (right side under tank) to adjust idle, it doesn't seem to play well with others.. Once the idle drops below 1500 it really plummets to 1000 where it won't stay idling well.. adjust it up a bit and its hit and miss until it sits at 1500 rpm.. the sweet spot it would seem.

 

When the bike idles at 1000 rpm, it will run kinda smooth, then not.. it sounds like it wants to stall.. then not.. then maybe.. then.. ok die already.. sheesh.. If I blip the throttle a little it will go up in rpm, hang around 1500 a bit and down to 1000 where it sounds like it doesn't want to be there at all.

 

I synch'd the carbs. Though they were done the week prior to the pickup coil dying, they were really out of whack.. each pair and the two sets were out by a good bunch. Now they are set properly, but the problem persists. I did notice the idle change a lot during the synch process.. needing to go up and / or down until 4 carbs were synch'd.. and idle set at 1500 again.

 

I checked the choke mechanism for smoothness and the 'pistons' it operates.. all come out and all go in properly, as far as I can tell. All 4 cylinders are putting out heat so nothing amiss there..

 

The air filters were done a week before she died of the pickup coil when the bike was running properly, and nothing suspect would cause concern there.

 

I went as far as passing an unlit propane torch in and around the boots to see if the revs would change, perhaps indicating a leak but nothing changed.

 

Somewhere along the line when I re-installed everything, something went pooched up again.. The fuel line is clear and free, all the vent lines are clear and free (not clogged or pinched).. Fuel has been Seafoam ad nauseum.. fuel pump tested Ok and new fuel filter.

 

I can leave the idle at 1500 and ride away.. but it's masking a problem.. The wonky start is probably attributed to the same issue.. once resolved this bike will be awesome again..

 

I'm out of ideas after going through the search features in the forum..

 

Any thoughts or ideas that I may try next?

[Neil86]

Any chance during the looking for spark checks that perhaps one or more spark plug caps were not seated back onto spark plugs?

[Marcarl]

I'm not that well versed in 2nd gens,,, well I know some things,,like they are slower,, but that doesn't matter in your case.

I would check the air filters just to be sure,, never assume anything when it come to engines and such.

Next, redo your carb sync,, it seems odd that it was running fine after the last sync but changed when you had issues,, that should not change the sync one bit. When you are done with the sync it should be idling at 900 or so with all carbs drawing the same. If you have issues trying to get them ALL the the same, maybe you are turning on the wrong screw(s). The idle will go down and up by turning on a sync screw, so you might be thinking it's the idle screw, but maybe is not,, but the sync screw instead, so in the process the sync would get screwed out of adjustment.

[djh3]

Provided the sync is good, I think it point to the idle circuit of carbs. More than likely it just has some sort of gunk in it from sitting. We use to take air filter off car, bring rev up and then close off top of carb with hand or a rag until it about quit. Then let it stablize out and do it agin. On the bike I would guess for all the carbs.

[Seaking]

Any chance during the looking for spark checks that perhaps one or more spark plug caps were not seated back onto spark plugs?

 

Thanks Neil.. That did cross my mind.. it also occured me to me that I did change spark plugs but honestly can't remember if it was before or after this last stint.. (so many parts, so little memory).. I'll check those tomorrow and hopefully find something..

 

Apart from burning more fuel letting it idle at 1500 rpm, is there any other harm that can come to the bike by leaving it as is for the time being until a fix is found? It runs great while riding, lots of power, no backfire or anything amiss other than the idle issue..

[djh3]

One thing I can think of is you may have what we use to call "dieseling" or "run on" after you turn the engine off. Because the RPM are high and of course drawing more fuel it will want to run after the key is off. It will stop, but it just has a clunky pingy sound momentarily.

[Neil86]

If you are still running the Dyna igniter....any chance the setting switch was disturbed...I know a few have had grief with erratic

operation using Dyna...thinking maybe it got disturbed somehow...never messed with one, understand some use dip switches to select

modes.

 

Any diagnostic codes showing on the Dyna?

Edited August 10, 2014 by Neil86

[Seaking]

Thanks Neil, I had a look at the Dyna before putting it back in to make sure I had the same settings, it's set on curve 3 as before. I have the OEM igniter unit and tried putting it back but for the life of me can't get it to fit in.. Its a bit larger than the Dyna and for all intended purposes, acts like the cables are way too short to slide down and onto the two studs..

 

I'll be taking the bike apart again this afternoon and may swap it out and manage somehow to jumper the battery to the leads on the bike since there's no room for the battery in the box with the OEM igniter unit not properly installed..

 

I had the bike out this morning and it started right away on the first go of the starter button, but wouldn't hold a low idle.. if I keep the idle up at 1500, it will idle fine.. sometimes dip to 1000, but won't die.. set it any lower than 1500 and the bike will idle fine for a bit and then falter... and die if not attended to..

 

Other than that, wow does the bike perform well while riding.. it's just that grrr idle issue causing the remaining grief..

 

I'll let you know how it goes.

 

Thanks again

[Neil86]

Does the model of Dyna you run have any diagnostic lights?

[Seaking]

Does the model of Dyna you run have any diagnostic lights?

 

It just has a red light to tell you when it's on.. I swapped out to the OEM ingniter box and the problem persists. New spark plugs, same story.. Can't find if there is a vacuum leak or intake leak with use of propane around the boots etc. Starting to think that something got into the carb causing an issue with the idle circuit. I had the fuel lines at the pump and carb body off to check for obstructions and its possible that dirt got in the system..

 

Though the bike will idle fine at 1500 rpm, its still ridable, starts ok.. awesome running. When I have the time I'll have to pull the carbs out and give them a proper cleaning.. or it will clean itself out with some Seafoam for the rest of the summer.. Impressive how well the bike runs on the highway and back roads.. smooth engine, lots of power.. no popping or backfires.. just smooth power.. its only at idle that there is a problem..

 

I'll give the carbs another synch tomorrow, see if it's displaced at all since the other day..

[billmac]

when you have your sync tool hooked up can you turn the idle down to 1000 and how does it idle? may be one of the plugs or hoses on the carb is leaking air throwing the idle mix off. I also ride a couple or more mile just before I sync the carbs so the motor is nice and warm and the carb heaters turn off. don't know why they always come on when I first start even when its 70+ degrees out. two min of idle will usually turn them off.

[Seaking]

Thanks Billmac.. I do my carb synch right after I get back from a ride, the bike is nice and hot.. From the propane tests I did, nothing seems to be leaking as there is no change in rpm when applying propane near and around the carbs, boots, hoses, vents or caps.

 

To synch the carbs I have to leave the bike at 1500 rpm so the engine doesn't quit.. If I attempt to bring the idle down, I need a third hand to hold the throttle to keep the engine alive while adjusting the screws.. Even then, with the carb synch adjusted properly it won't hold idle long enough to say it's stable.. it'll hold.. and falter.. blip the throttle to keep it alive.. holds.. falters and will die if throttle not attended to..

 

Starting the bike from cold, all four jugs make heat so there isn't a dead cylinder to note a bad spark feed or bad coil.. even when it starts at 1000 idle.. but it won't keep long before faltering and conking out.

 

At this point, I don't think it's the carbs being out of synch that's causing the issue. Nor do I believe its an air leak or vacuum leak.. I leaning towards something caught in the idle circuit in one of the carbs..

 

As it stands now, leaving the idle at 1500 renders the bike useable, as the bike rides like never before.. smooth power, tons of power.. but a higher than normal idle..

 

I'll be visiting a professional mechanic friend of mine who can properly check for leaks in a way I can't do it.. maybe it is.. maybe it's not..

 

But the good news is that while doing all this work I finally discovered what was making that light ting ting ting noise in the front of the bike.. I could only hear it while sitting in a certain position but not if leaning forward or sideways.. and it could only be heard while riding.. annoying.. Turns out one of the screws holding down the front left valve cover had decided to go on it's own with the second one packing it's bags as well.. the cover was fluttering a bit.. Oddly enough, no oil was leaking from this cover.. but this would have no effect on the low idle weirdness.. Note: check your valve cover screws.. I would wipe mine down but never noticed it being loose.. only by spotting the open screw hole was I able to discover it.

 

Fun and games..

[djh3]

Post #4 Man I hope you get this sorted out. But I dont really miss the 4 e-mails a day. So I know your out riding some anyways.

[Neil86]

Next time you are doing more investigation.....remove the left side cover so you can feel the fuel pump lid and note the frequency of the pulses at the 1500 rpm, then drop the rpm to 1000 rpm and see if it continues pumping albeit slower or stops.

 

Also if you can find a spark tester that you just touch to spark plug wire check that all 4 are firing when it goes into this wobble at normal idle.

[djh3]

Neil-I presume your talking fuel pump rite?

[Carbon_One]

While doing the syn keep an eye on the gauge so that you might get an indication as to which cylinder is causing the idle problem. In other words say #3 falls off first when the idle starts dropping then I'd check that carb first. Thou going thru all of them might be the better solution.

Larry

[Neil86]

DJH3

No...I'd want to be sure the fuel pump control circuit isn't dropping out at lower idle speeds.

[Seaking]

Soon as I got the problem fixed I took off on a 5000 mile road trip...

 

OK, so the rough idle and last problems were caused by a bad pickup coil.. the 2nd one.. go figure eh?! Though the resistance checked properly, there was still an issue with it.. so they refunded my coins and gave me a new one. This time it worked! And wow, did it ever get rid of a lot of the long suffering little annoyances I had with this bike. NICE!

 

The problem with the 2nd pickup coil was that though it would pick up the signal, once it heated up it would start dropping the signal here and there.. So after a ride and arriving at a light, it would hold idle without assistance.. Nor would it start every time.. but turning the key off and back on would just about work every time.. Not good.

 

Discovered it was the new pickup coil by putting a test light on the spark plug lead and watching the spark sputter out here and there while on idle... it did this intermittently with all four jugs.. Run the revs up and it would show a good spark throughout.. but not back at idle..

 

So a new pickup coil was needed and well sure enough, an 8 week national back order would mean no road trip.. hence why the free coil, it's from a different bike but with all the same specs. Straight bolt on, solder the wires up and bam, wow.. what a difference..

 

Whereas the key switch died earlier, then the side stand relay, I replaced the starter relay 'just because' since I changed everything else.. it was like a cascading effect.. right down to the pickup coil.. However, the charging system is working awesome.

 

Based on all I had been through and had to go through in order to get this bike running awesome again, I've deducted that the pickup coil was going south for a while now before finally dying cold. All of the previous annoying issues I had in the past are gone now..

 

After 5,000 + miles of 'test riding' all the low engine rumbles are gone.. the engine has never been smoother.. Others suggested colour tuning the carbs but it was the pickup coil (rumbles were still there after all the other components were changed and before the final pickup coil)

 

Hang starts.. for a while now, every once in a blue moon or more often than not, when I hit the starter button, the engine would turn and feel like it was hanging up against a compression stroke somewhere.. sometimes resetting my odo and radios. It even did this once or twice after the major component changes, but never once after the final pickup coil change. Go figure that with 12-14 hours of riding a day cross country, the bike did a lot of start ups in the heat, cold (Northern Michigan night temps dipped to 40'F brrr..) and in the rain.. never failed to start, lighting up magnificiently every time..

 

No choke needed. I haven't used the choke on the bike since putting in the last pickup coil.. even when parked over night in 60F weather.. wow, that's never happened before.. I always had to add a wee bit of choke to get the engine to light up after a few hours in moderate temps.. Now it's simply clutch in, neutral, hit start button without a twist of the throttle and she lights up.. and quickly gains idle revs (1000 rpm)

 

Mileage. Again wow..

 

With the VMax rear diff on my bike, I ended up with surprising and consitant mileage while traveling through the USA plains and mountains.

 

Running on the highways at 80 mph (revs at 4100 rpm) I ended up with 38 MPG

Running on the highways at 70 mph (revs at 3550 rpm) I ended up with 43 MPG

Running on the highways at 50-60 mph would give me around 48 MPG

 

Going through Vermont and New Hampshire mountains on RT 9 in 4th and 5th gear rolling at various speeds gave me 43 mpg.. (wow, what an impressive route! =)

 

...and somehow got a whopping 58 MPG while cruising in 5th out west.. hit reserve at 200 miles..

 

While running at 70-75 MPH on the speedo I hit reserve at 175-180 miles fairly consistently.. Makes fuel plan management so much easier now..

 

So though the other components died on me, they just caused the bike not to start properly.. but the pickup coil was the culprit to a lot of issues this bike had.

 

All I need to do now is replace the exhaust gaskets since I had the pipes off so often and check for Y pipe cracks while the pipes are off.. and the bike is like new..

 

Long story short: Bike is back better than ever.. And I'm gone riding again.. =)