strange behavior

[c.salt]

Haven,t posted in a while but I'm stumped.
Rockster been running well going down the road, dry day and pull up to a light and idle speed drops out. Stalls out, need to bump up idle via warm up lever to keep it running at idle, upper rpm's pulls along ok but a bit rough.
Examine cables, pull plugs and find secondarys fouled(not the first time finding this). So I figure its time for stick coils and pony up the $250 for new ones. Stick them in bike fires right up but still doesn't want to idle at1100 (drops out to about 650 to 700 then stalls).
A djust the cables raising the idle to 1050 by tightening the right side throttle body and then do a t.b.s. but don,t really get a great result (left t.b. is pulling stronger on twin max) Not bad but has run smoother.
So my question is if it wasnt the stick coils that caused lo idle what can it be. Cant see the cables changing that much. Searched for vacuum leaks, changed a few questionable hoses?
Motronic unit? Should I try a reset if so can anyone tell me how to do that.
Thanks
Doug

[sweatmark]

So my question is if it wasnt the stick coils that caused lo idle what can it be. Cant see the cables changing that much. Searched for vacuum leaks, changed a few questionable hoses?
Motronic unit? Should I try a reset if so can anyone tell me how to do that.

Others here can offer better advice based on experience, but I'll throw out a couple ideas:

Fuel filter?
Other fueling issue (fuel pump, injector fouling)?

Motronic will reset if battery is disconnected.

[NoRRmad]

I don't quite understand your description of your idle speed and Throttle Body Sync procedure. If the left cylinder is pulling more strongly at idle, then the idle-speed TBS process hasn't been finished. (A little dirt in the adjustment ferule can throw things off.) I'd sync the engine at idle, adjust the idle speed to taste, re-sync re-adjust and so forth until you're satisfied. A fan on the cylinders will give you more time to tinker without overheating. Make sure the battery in your twin-max is fresh.

Hope this helps...

[iowabeakster]

The original problem: was running fine, then it begins to sputter and loses idle.

ideas...

1. You changed secondary plugs and coils. What about the primary plugs? Check the wires and connections too. The ignition is my always my first and primary suspect. Test and verify that all plugs are firing reliably. Once spark is completely ruled out, move on to other things.

2. It could be fuel related. Water in the bottom of the gas tank, old gas? Seafoam, Heet, and fresh gas...

It'll be harder to diagnose, since you have been making throttle adjustments (multiple variables now in play). The synchronization of the cables on the throttles should not affect the idle (the throttles should be completely closed at idle). If the cables change the idle (or balance at idle), they are too tight!

You should use the Big Brass Air Screws to adjust the idle, not the cables. The throttle valves should be resting against their stops at idle. The air for the engine at idle is supplied by the bypass regulated by the big brass screws. Remove and clean the big brass screws (the idle screws). Spray carb/throttle cleaner in the ports. Verify that the o-rings on the big brass screws are clean and sealing properly. A good starting point is 1.5 turns out from completely seated (lightly). Adjust so that the are balanced and at 1100 RPM. They should be roughly equal in adjustment (small difference is OK).

If you can't get them balanced and running smoothly, you might have an air leak between the throttle body and cylinder head. This has been a problem for a number of people.

[jas]

I posted this last year and referenced it a couple times - it may be worth checking:

I had a similar problem earlier this year, stick coils helped but did not cure the idle lope. I posted the following in the Rockster forum:

"Recently my mileage started to suffer, idle was all over the place and the bike generally ran rough. The first thought was the dreaded stick coils, although after troubleshooting I could not single out a bad coil. Next I changed the plugs, spec’d the valves and completed a tbs (could get the throttle bodies close but not right on).

After much frustration I took the bike to a local independent mechanic (Mitch’s Motorcycles) in Boise. A few days later, I’m back on the bike and it runs like a champ. The primary issue was an air leak at the intake manifolds. The manifolds became warped over time and the o-ring did not seat properly. Evidently this happens over time, and the extreme hot and cold conditions that I ride in (sub freezing to 100+) do not help any."

To trouble shoot an air leak, put water in a spray bottle with a light soap solution and spray or pour over the junction between the cylinder heads and the intake manifolds. If a leak is present, you will hear/feel a change in idle as the water temporarily closes the gap created by the warped intake manifold surface.

[c.salt]

Thanks for the replies,
Been busy so haven't had a lot of time to mess with it. It runs o.k. but could be better. The b.b.s. are backed out to about 1 turn. Need to go back and start at basics on cable adjust. My guess is on pulling and cleaning air jets since adjusting the b.b.s. didn't change idle much.
Tightening the t.b.cable allows more r.p.m. at idle but it hides an existing idle issue. When I get a chance I'll play with it some more. At least its on the road again.
Stick coils did help but there is more
Doug