spark plug cap resistors?

Replaced my ignition coils earlier this year with Chacal's green dyna coils, NGK BP7ES plugs and new wires with standard crimp on ends from the auto parts store. Do I actually need "resistor caps" on the end of my wires that hook onto my plugs? Just using the rubber 90 degree caps over the crimped ends.

 

Yes you do.

 

Would it be possible for the non resistor caps to be causing improper ignition or a miss? Have done everything to try and figure out why the thing is chugging at higher rpms. Cylinder one doesn't want to fire at idle and I've repeatedly cleaned the idle circuit. Compression is good and cannot find any vacuum leaks.

Makes it impossible to properly colortune...

 

Since you are also running non-resistor plugs it very well could be. The resistors supress EFI from the plugs. Unsupressed EFI can mess with the TCI and cause a misfire.

 

why not just get some resistor plugs ?

 

I've got resistor plugs - NGK BP7ES. They're resistor plugs; have the R designated on the insulator, but not within the actual model number.

 

if they were resistor plugs, they would have the bpr7es label on them.

CN

 

Paranoia got to me. Went and checked; cylinder 1, 2 and 4 have BPR7ES plugs, but 3 had a BP7ES non resistor plug. I'll stop and pick up the correct replacement tomorrow, but I really cannot imagine that one plug causing bogging and misfire issues, especially considering number 1 is the cylinder not firing at idle. It's only gets partially warm as opposed to the other pipes. Shows spark...

 

Actually this makes perfect sense assuming that #1 and #3 plug are connected tot the same coil and fire at the same time.
The current from the plug will choose the route of the least resistance and that is through the non-resistor plug (#3).
#1 gets what is left and that is probably not enough to ignite the fuel in the cylinder.

The new plug should make a difference.

 

^^^^ exactly. I doubt that #1 is firing at all because of the one non-resistor plug. Whatever warmth the #1 header is getting is from the head, and not from exhaust gasses.

 

#1 and #4 are on the same coil, #'s 2 and 3 on the other..........

 

Yeah, I knew 1 and 3 weren't on the same coil, so that leaves me a bit paranoid yet. Stopped quick at the parts store and they were out of ngk plugs, so I got the Autolite 63 equivalent. First thing I noticed was the piston tapping against the spark plug. Took the plug out and it is slightly longer, so it'll have to be tomorrow before I can get a ngk elsewhere.

 

the path of least resistance is true for a parallel circuits where there are two paths but the plugs are a series circuit, one way in, one way out

 

The plugs that are on the same coil are part of a parallel circuit. If they were in series you'd have one plug wire from the coil connecting to the first plug, another wire connecting the first plug to the second, and the second plug grounded to the case to complete the circuit. That would leave plug number one (in this model) hanging in the air.

I was not thinking about which plugs are hooked to which coils, so the one non-resistor plug does not explain #1 being cold.


It'd be a good idea to confirm that there is spark on the cold cylinder. Premade plug wires are usually made correctly, but a no-spark condition is less work to fix than a fuel delivery issue.

 

Polock has this right in that it is a series circuit.

SQLGuy explains the wasted spark ignition quite well in the How To: Ignition Troubleshooting.

As for resistance required he noted this in his write-up:

"The resistors in the plug caps serve not only to reduce electrical noise transmitted by the ignition system, but also to reduce the current flow once the spark is ignited, which lengthens the burn time of the spark. With no resistors, the spark will be more intense, but much shorter in duration."

Since fuel mixtures, spark intensity, and spark duration are all interrelated, having one non-resistive plug could cause one of the two cylinders connected to that coil to have an issue, while the other cylinder may behave normally.

Hopefully, changing to the correct resistive plug will solve the problem.

 

[/URL][/IMG] [/IMG]
if you add the red and take out the purple you have a parallel circuit. you would also get very shocked if you touched anything on the bike with wet shoes on.
it goes out #1 wire, sparks #1 plug, goes through the head, sparks #4 plug, goes out #4 wire, back to the coil. one path, series circuit
excuse me, i'll be back when i figure this out

 

Pure SQL Awesomeness, or, What You Need To Understand About Ignition Coils:

http://www.xjbikes.com/forums/index.php?threads/how-to-ignition-troubleshooting.21932/


NOTE: for the electrically semi-literates amongst us (I was one, too, so don't feel bad about it!) you'll need to read thru that entire post one step at a time. Make SURE you understand what is going on, electrically (i.e. flow of electrons and the function/signaling it provides) in each step. When you get to a point you don't understand, stop, re-read, ask questions, etc.


Here are the key points to recognize, with particular emphasis added by me via bolding, underlining, coloring:


SQL:
8. Once the coil is fired, there will be 20KV or more between the two ends of the secondary winding of the coil. The two components of this voltage potential will want to reach each other to complete their circuit. To do this, current will need to flow from one end of the high tension (secondary) winding, through the spark plug wire, through the resistor in the plug cap, across the gap of one plug, through the metal of the cylinder head, across the gap of the other plug, through the resistor in that plug's cap, and up the other plug wire. Yes, the cylinder head is grounded, but, since the secondary winding of the coil is completely insulated (from the rest of the bike's electrical system), chassis ground means nothing here other than another conductor in the current path between the two ends of the high tension winding (in the secondary side of the coils).


RESPONSE >>> I have to raise the red flag at the idea that current flows from one end of the secondary, through one air gap, across the block, through another air gap, and back up the second plug wire to the other side of the secondary. That, electrically, makes 0 sence.

When the primary side EMF collapses, it collapses "through" the secondary side windings, creating a current flow in the secondary. (Like how a generator works)

This secondary current will want to reach ground any way it can. So the current splits, half to one plug lead, half to the other plug lead. Both currents jump the air gap and go straight through the engine block back to (-) on the battery.



SQL:
I haven't been on this board in a long time, and I don't know if you are still here either, but I thought I'd respond just so other readers aren't mislead by your misunderstanding. You were correct until you started talking about ground. Ground has no relevance to the secondary circuit. (note: he is talking about the bike's main electrical system.....powered by the battery, where all electricity originates from and returns to via ground.....and it is this "ground".....in the main electrical system of the bike, which has "no relevance" when talking about the secondary side of the ignition coils because the coil secondary circuit is a totally separate, isolated "electrical system" from the bike's main electrical systems).

Take a look at the schematic in the service manual, or just draw out the circuit, and you should be able to see that you're mistaken.

The secondary coils are not connected to the primaries, they are isolated. When the field collapses, a potential is generated across that secondary coil; you could easily draw an equivalent circuit with the secondary as a high voltage battery. Current flowing from/to that "battery" is just like current flowing from/to a regular battery - it's going to "want" to flow from one end to the other through the path of least resistance. That path has nothing to do with the battery, TCI, or anything else on the primary side of the coil.

One other exercise you could try, or imagine, if you still don't see it: what would happen if you took out the two spark plugs that are on either (same) coil, left them plugged into their caps, touched their bodies together at the threads, and cranked the engine? Answer: Both would spark - without any connection to chassis/main bike electrical system ground involved.



All of the above issues are what Polock is attempting to illustrate (I think!)

 

New non resistor BP7ES NGK plugs, new NGK resistir caps, and new copper core wires. Bike is still cutting out at 5000 rpms in all gears. If I remove the plug wire from cylinder one while the bike it idling it doesn't really change, but there is definitely spark. I moved the wire from #1 to #4 and vis-a-versa and there is no change. Removing the plug wire from #4 kills the bike no matter what wire from the left coil I'm using.

I'm confident that the issue has nothing to do with the ignition system. I've cleaned the carbs more times than I want to admit; new shaft seals, valves in spec snd carbs synced. Compression is good on all cylinders now. I'm out of ideas...

 

If you open the bowl drain screw on the #1 carb, does fuel come out of it?

Is the exhaust header pipe on #1 hot, warm, or cold?

 

Fuel does come out; it is filling. Pipe is warm. Gets hot when I use choke, but otherwise just warm. It's like it's firing sporadically when on the highway. It almost has to be a carb issue, it's just not getting fuel. Carbs are off right now and I once again verified the float level, which is fine.

 

It's a little odd that it runs okay (??) up to 5000 rpms, and only then starts performing badly (fuel starvation).........that would seem to indicate a main fuel circuit issue rather than a pilot circuit issue, and the main fuel circuit is rather large, and hard to plug up with varnish, etc.

Check the fuel inlet (flat valve) assembly, see if the screen is plugged or if the needle has any damage. Make sure the vac piston slides freely, and that the needle hasn't starting to come out of it's plastic head cap. Check vac piston rubber diaphragm for tears, holes.

I assume valves have been set to spec and compression on that cylinder is okay?

What does that #1 plug look like (compared to the others)?

 

Compression was addressed in an earlier post:

XJYamaha wrote:

Head gasket installed and the bike fires up and there are no leaks. Compression is consistently 120 on cylinders 1-3, and closer to 130 on cylinder 4, so that's good news at least. I did then put a bit of 20w 50, very slight amount, down each cylinder and rechecked. Compression results shot way up, 210-220 per cylinder. Could this be due simply to the heavy oil I'm using to wet check, or does it also indicate my rings are in needs of maintenance as well?

Minimum spec for the 650 is 128, it was suggested to run it and test again, but that never appeared.

Diaphragms were also addressed in an earlier post:

XJYamaha wrote:
-Valves are in spec
- plugs, wires and coils are all within a few months old and all test fine
- New carb to airbox boots and resealed the intake boots
- New aftermarket carb diaphragms
- Carbs were all vacuum synced
- New OEM air filter

Wizards can weigh in on the out of spec compression.

 

I've run the bike a few times and rechecked compression. 1-3 all test right at 120, with #4 coming closer to 130. Adjusting the sync screw on 4 does seem to have more of an effect compared to adjusting 1 and 2.

 

So with the new diaphragms the holes in the slides are oriented towards the engine?

As for the idling issue were the air jets checked on each of the carbs?

If you are using a Haynes they have them labeled incorrectly.

A - larger hole is the pilot air jet, they have "A" labeled as main air jet
B- smaller hole is the main air jet - they have "B" labeled as pilot air jet



Per RickCoMatic

The POSITIONS of these two Jets, in the photograph appearing on pg. 123, are CORRECT.
3 Holes - Right side looking down and in.
LABELING of the 2 Jets is NOT Correct.

 

Has the engine been synched?

 

I've checked the placement of those jets more than once, and they are indeed correct. The plug on #1 is a tick on the whiter side, and I've incrementally tried bringing out the mixture screw, but since I've been unable to colortune any of the cylinders besides #3 I'm shooting in the dark. Cylinders 2 and 4 won't turn orange and #1 doesn't ignite unless I use choke, so I don't know how accurate the mix actually is.

I've repeatedly hooked up my 4 gauge carb sync and they're always where I left them previously. This really seems like an issue with a blockage somewhere, but it seems nearly impossible with all the cleanings I've given them. Since they're off now I'll go ahead and shoot more cleaner and compressed air through the passages. If I don't get it this time I may just have to find a reputable mechanic next spring to have a look.

 

"If I remove the plug wire from cylinder one while the bike it idling it doesn't really change, but there is definitely spark"
#1 plug isn't firing where it should, it's firing up inside but not at the gap. Get a new set of plugs

 

Plugs were new as of this afternoon.

 

Since your cleaning again, be sure to give extra attention to the two transfer ports that sit under the throttle plate. If you use a bristle from a parts cleaning brush they measure right at a 1/4" deep.



So do the holes on the bottom of the slide face towards the engine?

 

Thanks for the tip, and yes, I always make sure to face the two holes in the slide towards the engine.

 

Also, the fact that seating the mixture screw on cylinder number one has no affect on idle kind of verifies there is something going on with the carburetor in my opinion.

 

Did notice the throttle plate on number one completely covered the first hole as shown in the picture above. I took the plate off and gave the bore a slight sanding with 1000 grit, as well as the plate itself. Put the plate back on and the hole is just barely visible, as are the other 3 carbs. Not sure what effect it'll have, but it couldn't have been helping at all.

 

I had a similar issue when I got my bike. Using a colortune I was able to get a constant ignition only when I opened the fuel enrichment system or opened the pilot screw about 5 turns. I finally found a bad intake gasket was the problem. I replaced it and the problem went away.

 

Finding that throttle plate nearly completely closed after doing a running sync is a good indication of a vacuum leak as tabaka45 mentioned. To compensate for the vacuum leak, the throttle valve would have to be closed off to achieve the vacuum of the other cylinders - or if no vacuum leak, then compression would have to be an issue. Either the gasket or the boot could be leaking - Bigfitz52 has mentioned on several occasions that one of the most frustrating vacuum leaks occurs right at the spigot on the manifold. - either through cracks or from hardened vacuum caps.

When you removed the throttle plate and re-installed it if more of the hole was exposed then most likely is not centered properly. When you install it, hold it flat against the throttle shaft, if it does not close completely covering the holes then back off the sync screw until the holes disappear. Then secure the screws while you hold it in this position.

Purple Loctite is also recommended for those throttle shaft screws - blue would be the next choice.

 

Cylinders #2 and #4 have a real problem, typically it's unusual to be unable to get cylinders RICH. Try using a bit of choke and see if you can get them to go rich (orange)......if so, then either the pilot fuel passage is partially blocked, the fuel level is way too low, or there is a big air leak somewhere. #1 sounds like it has a blocked pilot fuel passage, or perhaps the mixture screw o-ring is missing or damaged?

 

I've been blasting carb cleaner through all the ports/passages and may have stumbled upon something. Shooting carb cleaner through the enrichment circuit, next to the pilot air jet, I am getting a bit of carb cleaner bubbling up through the choke plunger assembly on top of the carb (up through those little rubber caps). The caps that sit on top of the choke assembly are the only rubber parts on the carbs I haven't replaced.

I've propaned and carb cleaned those rubber caps with the bike running and can never get the idle to fluctuate at all, but could this actually be my issue? If this is my phantom vacuum leak it would explain my inability to colortune, and maybe my 5000k rpm stumbling?

 

I do think you're on to something. With the enrichment plungers in the down position there should be no leakage past the seats. I'd pull the plungers and inspect the seats. They can be polished so they seat properly. The rubber caps on the enrichment plunger shafts are dust seals.

 

I'm thinking like chacal and k-moe. Re-visit the enrichment wells. Possible issue could be swapped or missing o-ring and washer. Also imo eliminate the guessing game. You know the coils are okay. I'd add the bike specific resistant caps + non-resistant plugs, put the multimeter to em', get the correct ohms reading and move on to the next maintenance item. Just saying.

Gary H.

 

Enrichment wells don't have any orings or washers on my bike, just the dust caps on the top. I polished the plungers and seats, and put everything back together. The carb cleaner coming up the plunger is entering the well above the seat, so that explains the cleaner coming up through the dust caps. To me it seems if the cleaner is indeed bypassing those caps then it is a spot open to a vacuum leak, regardless of the enrichment is opened or closed.

 

Agreed ^ and Sorry, I meant to say mixture wells. Bp7es plugs and 128 compression. 650? if you remove the mixture screws there is a tiny spring, tiny washer and tiny o-ring in the bottom of the hole. A round wood tooth pick will fish them out without hassle.

Gary H.

 

I put new washers and orings with the mixture screws a couple months back. The enrichment circuits on the other hand have no washers or orings.

 

I agree and apologize again. I meant to say mixture wells. You've replaced them. You're on it. I'll shut up now.

Gary H.

 

Ha, no problem. Just a bit of communication breakdown.

 

if the hole your putting cleaner in is for the enrichment, and it were a vacuum leak, think about where it would go. into the float bowl, the same place your putting the cleaner. so it would just be another way into the float chamber.....not a vacuum leak

 

You could check that the the inlet manifold on 1 is not leaking.

also check the fuel mixture screw circuit is clean,this is easy to overlook,and the o ring washer are both there and in the right order.

 

Interesting find tonight. After finishing the clean, mixture screw examination and reassembly, I put my carbs back on and the bike wouldn't start. Pipes 1 and 3 were warm from the attempts, but 2 and 4 were cold. I unscrewed the drain plugs on those two bowls and got no fuel.

I took the carbs back off and put them on my PVC stand I use to check float levels, and without the bowls in place I wasn't getting any fuel draining past the needles on 2 or 4. When taking the needles out I got plenty of fuel flowing through the seats, but nothing when the needles were in place and hanging; I took the needles out and compared them to a spare I have on hand. The rubber tips were quite swollen and regardless if the float was hanging or not, fuel wasn't making it past the swollen tips.

I checked the needles on 1 and 3 and they too were a bit swollen, but not as bad as 2 and 4. I'm assuming my carb cleaning and compressed air may have added to the situation, but I'm hoping perhaps this was why I seemed to not be getting quite enough fuel in the first place. I'll stop at the dealership tomorrow and see if they have any needles on hand.

 

The carb cleaner caused the viton tips to swell. They will shrink back to their normal size in a few hours. You don't need replacements.

 

Ah, good to know.