Hot skip...idle

[jasonm.]

1st ...I have had my 87 Royale for 20+ years. And done many Mods and work. I have 30 years as an electronic tech. But I have been having this HOT idle skip. EX: been riding on a hot day. Get off the hiway to my house. Pull up the driveway. Open the garage and the idle starts missing. I can see the tach dipping..I hear the spark plug caps arcing and can see it on the right side caps(3,4) sparks to the head. AH, I replace the caps and wires to ALL coils. Stiill no help when hot. AND if I rev the bike the issue goes away for a 30 seconds then returns. I ohm out the pick up coils. All good. Primary side of the ignition coils.. test good even when HOT...OUCH. I replaced intake o-rings AND We can rule out the carbs because I had the bike EGA'd ...it's not rich... running 13.5:1 a/f @ 1000rpm. CHanged to non-resistor spark plugs vs. resistor type...no difference. Since the bike can idle smooth on first start of the day w/o choke...Thus , I think a hotter range plug will not fix this. As a cold engine is more difficult to ignite fuel. Also, I do not see a "rev limiter" wire in the schematics. Typically from the tach to ignitor. As this has been a documented problem on my Yamaha Vision. Again, if I increase revs it's good for as hort few seconds. I am thinking it the ignitor getting heat soaked OR secondary side of the 2 right coils are bad...BUT then again, reving it shiould not temp. make it run good. Any experience out there with an issue like this???

Edited August 1, 2011 by jasonm.

[bkuhr]

Just a random thought may give you idea to test.

Have a scope handy? Might monitor primary's during both hot skip and normal with a thought ignition unit may be dropping spark when hot, also might try same monitoring input coils controlling ignition box.

[Yammer Dan]

Wouldn't know the why but could you use one of those Spray Ignition sealers to cure it? But if you are like me you want to know the WHY.

[jasonm.]

Good Idea. Yes, I have a scope...quite old. But my inductive lead, last time was weak. Maybe the standard lead will show me something? Also, Since I posted this. I have been trying to remove the coils. I have some perfect looking spares. DAMN...it's not easy. It would seem that I need to disassemble the WHOLE fairing. Does anyone know a short-cut to replacing the coils ? I just need to do the right side. Also, mentioned before... I have sparking right thru the caps...even new caps and new spark plugs. So either the spark plug caps are acting like a capacitor charging up. But not enough to jump the spark plug under compression...AKA weak spark/coil.....or...??????

Edited August 1, 2011 by jasonm.

[jasonm.]

I am 80% sure it's one or both right coils are weak. I did a test by idling the bike for quite a while. Then with the engine hot and the fan and brakes on. The reserve power of the battery is somewhat depleated. And the idle voltage would be 12.7v. w/fan on then 13v or so with fan off. And the voltage would slowly climb to replenish the battery. Turn the throttle to 1400rpm = 14.3 volts. I do have a good sealed battery that starts the bike hot or cold without issue. Thusly, It would appear the weak , heat soaked coil(s) need closer to 13v to fire good. When not heat soaked there appears to be no issue. Or when the voltage is well up above 13v. Remember this is strictly idle. Yes, I have the new Mosfet R/R. But that does not do miracles for a normally idling bike with brakes and fan on. As the coils are on a Bracket. That makes access to their individual mount screws seemingly impossible. And the bracket/frame bolts no easier. SO, does anyone know a shortcut to safely and efficiently remove the RIGHT side coils w/o removing the entire fairing ??? Or maybe there is a way by removing just the right side fairing pieces? Please no sawz-all jokes...

Edited August 1, 2011 by jasonm.

[dingy]

I have some spare coils you can have for price of shipping.

 

Gary

[jasonm.]

Seems I have found the trick for coil removal. 1st. remove the front coil. There is a screw that is starirng right at you and easilly comes out. Then using a good #3 phillips bit and a 1/4 wrench it's taped to...wiggle coil and carefully turn that phillips out. Then proceed to the rear w/1/4" socket and #3 phill taped in and assorted wobbles and extensions. NOW I just need to find the ONE phillips I dropped in the engine somewhere. I will use allens for remounting. Hope this solves skipping idle. Dingy, I have, what I hope are good spares to try.Thanks...

[Flyinfool]

Do some more checking.

With the bike hot and skipping try pulling plug wires one at a time. this will help you identify exactly which cylinder has the problem.

 

I have to ask the obvious question just cuz no one else did.

Are you sure you have the boots tight on the plug? They are a little difficult to get on tight.

If the boots are not on all the way, that would explain your arcing to ground.

[bkuhr]

Heres some scope readings I took a while back. I used standard lead backstab into TCI. Used old 1 channel, 2 channels would show differances better.

 

http://www.venturerider.org/forum/showpost.php?p=502850&postcount=10

[Condor]

Sounds like maybe a plugged idle jet. May not be electrical. Have you run any Sea Foam thru it lately??

[jasonm.]

Sounds like maybe a plugged idle jet. May not be electrical. Have you run any Sea Foam thru it lately??

It's not the carbs. As stated it idles perfect when cold...no choke, you can hear the cylinders fire one at a time. It's that smooth... and takes the gas instantly...when cold(no choke). If it was the carbs, it would hesitate, especially when cold. Plus the carbs were gone thru by me last year... new jets. None are cleaner than mine. I only run the choke for 20 seconds on very cold 1st starts. That's all. And had each carb/cylinder EGA set. New slides 10k ago. This is a HOT only issue. I did identify the cylinders with a timing light and the arcing was obvious as previously stated. Bkuhr, that's pretty much hat I was seeing on my scope. Yes the boots caps and wires are tight and properly in place. They are easy for me to put on. I do not have large hands. I use a good dielectric grease to prevent water and arcing issues on all wires. Just the outside of the wires. As this grease is an insulator. Last night, I removed the 2 right coils. Neither had any signs of outside cracking. Which is common. They bench tested cold good. BUt who's to say when hot? My spares only have cracks at the very outside edges where the screws hold them to the brackets. I hope they are good. Now I am trying to figure out whether to use coils closer to the UPPER or lower spec. for these? As higher resistance means usually more windings and more potential voltage on output. Or the lower spec. as these usually need less time to reach their discharge? If this does not fix it...then it's the ignitor. Oh joy...

Edited August 1, 2011 by jasonm.

[jasonm.]

Last night took the bike for a short ride after finishing changing coils and spark caps from crap NGK back to OEM.

Last night, same problem...idle it enough to turn on the fan ...then it skips and in fact I could see the front caps both arcing...Then the bike died. Restarts but repeats the problem. I have many OEM Venture caps all test good and physically look good. So I changed caps again. No difference. FYI- I found all my NGK caps only a year old to fail the 5k ohm test on my meter. Yet my 20+ year old Venture caps to be good.

I set the carbs to perfection last year. New float needles and set floats. I have had the carbs off 3 times. 1st bad needles( I have Sirius brand Canada needles), 2nd time set floats properly and third time- double check everything. In fact I set the floats "low" because the needles will "break in".

Then had it EGA'd . Me and the EGA guy(John) did it together. It's my bike so I made the adjustments while we both read the PC screen. He has a $15k dyno EGA. Now I am at the idea either something has changed in the carbs...at least 2 of them Or the TCI is failing when warm(hot). I am going to temporarily relocate the TCI to top of air box. If that changes things then...I know the TCI is the issue. If no change...then it could still be either problem. Wish I had a spare test TCI ignitor.

Got any other ideas?

 

Jason

[camos]

I hesitated to jump in on this because I'm not a "real" mechanic but I'm just not getting it. There are two possible issues being discussed here. While there are possible issues with carbs, they have had a lot of recent attention so the chances of them being the culprit are slim. The arcing however is a definite issue that needs to be attended to whether or not there is a problem with the carbs.

 

When things heat up they expand which could open a weakness in the caps enough to allow the arcing. When the engine is idling, the stator is producing the least amount of power and when the fan comes on it increases the demand all of which could reduce the viability of the jolt from the coils. Without re-reading the whole thread, I don't recall seeing any mention of the plug wires being replaced. The leak that is causing the arcing at the caps does not have to be at the caps since electricity does flow and will take the shortest or the easiest route to ground.

 

[capn eddie]

Just a thought are the caps sending spark to head or maybe cracked insulators on plug arking to head. i ask because i don't see two sets of wire caps sending spark to head and did you replace the wires just a thought.

[jasonm.]

All spark plug wires are new. And I do not get a jolt when touching them.Note: these listed below are all NGK items. Last night I find 2 non-resistor spark plugs "open" (yes they are cleaned). and they should read close to zero.. I found also 2 bad caps also NGK. These bad caps read "open" instead of 5k on the ohm meter too. I busted them open to see why. Turns out they are not air tight and I think a slight bit of sopemthing got in and turned the stud the wire connects to...but inside the sealed CAP's brass BLACK. This is something internal...nothing that could be seen. My ohm meter again confirmed this was the cause of the OPEN circuit. NOW Replaced w/good used OEM items> But still same issue.It sparks horizontal directly to the head on the front two. Nice light show. There are no cracks in the "good" OEM caps. The OEMS are good because they are "rebuildable". Which I did. They all ohm out at 9 to 10k ohms. The wires are new. Everything was "ohmed out". Makes me really angry As they only 1 year old...all items. Maybe the bad caps etc. has caused the ignitor to be bad when hot? I am relocating TCI it today to the top of the airbox.to see if cool air helps. ANyone know of a better/other spark plug or CAPS , NOT NGK. I think Autolites are at most Auto stores..like ADvance Auto...?KEEP the ideas coming.

Edited August 13, 2011 by jasonm.

[Condor]

OK since we're brainstormin' here. What type plug wires are you using, and when you plugged them into the caps and coils did you make really sure that the center pins made contact with the center core???

[dingy]

Jason,

 

I have a set of 8mm core graphite wires that were new last summer. Took them off this year due to COPS setup.

 

Cut to length for stock coil location on a 1st gen.

 

Caps have SB05E - 5K ohm on them.

 

Inside caps are bright, shiny brass.

 

Paid $55 for them, you can have for $25 & shipping. They will fit is a small priority box.

 

Gary

[jasonm.]

I am using the 7mm, 19 strand wire you see in the Dennis Kirk catalog. My local Auto store carries it. Very good stuff. Caps...the ones you show are the ones that went bad on me. I had 2 straights in back and 1 angled at front go bad. a 4th was borderline bad. Thanks for the offer...but no thanks. I never buying NGK anything again. DAMN...I just put NGK plugs in the wife's car 2 months ago....oh boy. Now I did the test w/TCI on air box. No difference. Although I now know it's seems to be just the #2 LF that's arcing. This was one with a bad cap and bad spark plug. Could have damaged the coil. AS FAR AS CONTACT...I AM ABSOLUTELY SURE EVERYTHING WAS INSTALLED TO PERFECTION. This is something I never rush. PLUS I use an OHM METER AFTER EVERY CONNECTION. PRIMARY AND SECONDARY RESISTANCES. FYI-I had the same thing happen on my last car. And the coil had split open, ... But at least that was obvious with arcing right out the coil. So this is another change out...oh boy. UPDATE 8PM. 8/13 coill change for #2 did not fix it... So I either have something that has changed in the #2 carb causing it to be too rich and borderline gas fouling and the spark has to go somewhere, thus to the head or............?????????? FYI, you cannot read spark plug when it's just idling. There is not enough mixture to make an obvious color change.

Edited August 14, 2011 by jasonm.

[jasonm.]

I think I found the cause. 1st I need to say it appears to be 2 things that are causing my issues. The 1st previously reported, was bad caps and plugs. 2nd- since the issue stayed on #2. I decided to check the fuel level. Could the level change in the last 3k miles from last year's work? I removed the air box. And using my "mini level" on the carb ...shimmed the centerstand till things were perfectly level. The bodies of the carbs were marked by me previously. Checked this time again and again ....Results #2 fuel level was 4+mm higher than it should be. The bad caps and plugs just just made this high level fouling issue show sooner, rather than later. As we all know, a warm engine runs richer...as the pistons/rings seal vs. a cold engine. So when hot...it was borderline gas fouling/flooding. Even with the idle mixture screw closed it still arced to the head..too much gas is too much gas. At least that is my take on it. Some may say 4mm is not much. Well if that was the case. Then, Why is the manual so specific on these settings? TO those of you who suggested...carbs. You were right. Me, with my idea, "bad coils", I was wrong but close. It was caps and spark plugs. That was a waste of time changing coils. As any coil that can spark from cap to head must not be bad. I should have followed my own rule. "check the simplest thing first" aka caps and spark plugs. And I will also remember, "just because it was good last year does not mean it's good now"...especially carbs and electrics. I will be ordering some parts and getting this done ASAP. I will let you know how it goes. Round #4 on the carbs. Unless someone knows of something I missed?

Edited August 15, 2011 by jasonm.