Topic: Spark plug cap resistance and whole lot more

[topperharley]

Il do that when i do the tube test.
Thank you very much. You have been really awesome by answering my questions. Cheers for that.

Lähetetty minun SM-G903F laitteesta Tapatalkilla

[PeWe]

If i use plugs with R then 0 hms plug caps are fine?

Yes.

Where can I find 0 ohms caps?
My bike did not like Denso Iridium resistor plugs. NGK D8EA work better. Caps NGK 5kohms.
I have looked for 0 ohms without finding any.

[flybox1]

I switched away from Denso plugs.
Always had a tough time with jetting.  NGK D8EA+5k caps are the way to go.

[topperharley]

If i use plugs with R then 0 hms plug caps are fine?

Yes.

Where can I find 0 ohms caps?
My bike did not like Denso Iridium resistor plugs. NGK D8EA work better. Caps NGK 5kohms.
I have looked for 0 ohms without finding any.

I looked from the ebay and i coudnt find any straight non resistor caps. Funny. Are you sure that your local dealer doesnt have any? We have those on our dealers stock.

[topperharley]

Here are the results of the clear tube test.
Pic 1 is cyl 1. The bike is allmost standing straight.
Cyl 2 i did not open the screw all the way. It felt like im gonna lose a treath if i do.
Cyl 3. The level is between cyl1 and cyl4. ( no photo).
Pic 2 is cyl 4. Bike is completly straight.


I wonder is the level on cyl 1 a bit too high?

[flybox1]

#1 is too high...adjust the float
#4 is too low...adjust the float

[topperharley]

So the goal is between cyl1 and cyl4.
This system is so delicet that it runs rich if the level is like 3mm to high or lean if 3mm too low?

[flybox1]

So the goal is between cyl1 and cyl4.
This system is so delicet that it runs rich if the level is like 3mm to high or lean if 3mm too low?

yes.

[Deltarider]

If your bike was leaning to the left a bit, it could well explain the difference. All these people that advice you to adjust the floats, should ask themselves what chances are that PO has ever touched them (readers of this forum excluded). It's OK to check, but think twice before you start tweaking the floats. Check float needles are not sticking and float pins allow floats to pivot easily. You can polish them a bit if needed. And above all: verify fuel can reach the floatchambers not hindered by kinked fuellines, extra inline fuel filters or blocked vent tubes.

[HondaMan]

If i use plugs with R then 0 hms plug caps are fine?

Yes.

Where can I find 0 ohms caps?
My bike did not like Denso Iridium resistor plugs. NGK D8EA work better. Caps NGK 5kohms.
I have looked for 0 ohms without finding any.

PeWe: you don't want to use 0 ohm caps. The coil (all coils) on these bikes need some resistance. Normal is at LEAST 5000 ohms, Honda OEM was 7500 ohms, 10,000 ohms is actually a bit better. If you use resistor plugs (about 2500 ohms in most cases), these work fine with 5000 ohm caps, making it like OEM again.

With no resistance, the spark will be VERY short. This does not make for good fuel burn, so the plugs end up dark from unburned fuel and the power from the engine is less, especially at high RPM.

[PeWe]

If i use plugs with R then 0 hms plug caps are fine?

Yes.

Where can I find 0 ohms caps?
My bike did not like Denso Iridium resistor plugs. NGK D8EA work better. Caps NGK 5kohms.
I have looked for 0 ohms without finding any.

PeWe: you don't want to use 0 ohm caps. The coil (all coils) on these bikes need some resistance. Normal is at LEAST 5000 ohms, Honda OEM was 7500 ohms, 10,000 ohms is actually a bit better. If you use resistor plugs (about 2500 ohms in most cases), these work fine with 5000 ohm caps, making it like OEM again.

With no resistance, the spark will be VERY short. This does not make for good fuel burn, so the plugs end up dark from unburned fuel and the power from the engine is less, especially at high RPM.

Thanks Mark for the clarification about plugs and caps. I thought that Denso iridium R plug with NGK caps ended up in too high resistance.
That plug might be good for racing with jetting for full throttle. I had to jet my Mikuni TMR32 richer with pilot jets for cruising within the speed limits and nice take offs without hesitations. Different on dyno and full throttle.
I'll continue with NGK D8EA that always has worked fine.  I have used DR8ES-L too back in the 80's without problems.
My coils are Dyna 5 ohms (black)
I have a pile of sootened plugs after carb jetting sessions. D8EA, Denso X24ES-U, NGK DRES-L, NGK Iridium....Maybe possible to clean without spark short ciruit sootened porslain - plug, less spark where it should

[Deltarider]

If you use resistor plugs (about 2500 ohms in most cases), these work fine with 5000 ohm caps, making it like OEM again.

I happen to have some halfway used sparkplugs lying around. The (4) NGK DR8ES-L all measured around 5kΩ, the (4) ND X24ESR-U around 8kΩ. IMO with 5kΩ caps it really adds up, so I would advice with 5kΩ plugcaps (mind you: 5kΩ when new!) to stay away from (R)esistor plugs. 

[topperharley]

I have a bad feeling about this. It could be that the problem in cyl 1 is valve guide. I remembered that there was some issues in cyl1 8 years a go.
I renewed stems but i didnt do anything to guides last winter.

I installed new plug in cyl1 and drove few km's. It looked like its fouled.
There is littlebit blue smoke coming from cyl 1 in cold start but nothing when shes hot.

Id really hate to do a guide fix now when the driving seasons started. The plug doesnt look oily. Its fluffy, dry and black.

What do you guys think. Would it be a bad idea to try a bit hotter plug? Maybe 7 or 6?

I also have open pods aka air filter.
Iv read that its an issue with these open filters that you should restrict air flow to engine. It could  make mixture adjusting easier.

Im gonna open air screws 1.5to2 turns out and see what happens. The outest that screws have been is 1.2 turns. The pilot jet size is 40.

I did adjust the float level in cyl1.
This is giving me grey hair and a headache

[topperharley]

Cyl 1 plug keeps on fouling. Float level ok. Pilot jet 40. Main 135. D8ea, d7ea both fouling. Air screw is now 1 3/4 open and its still getting fluffy. It runs good. Accelerates right. On deceleration it pops but only on low revs. If you close throttle from high rpm it doesnt pop. A small popping (maybe) is on idle too. You can just an just hear it. Other cyl plugs havent fouled not once.

Whats next. Please help.

[flybox1]

Stick with D8EA....those are correct.  Stick with 1 3/4 mixture screw setting.
You continue to say the plug fouls, but dont give us a throttle position which causes the fouling.
If you ride around town, and go from idle to WOT a few times, and everything in between, and then back home again, you really cant tell what throttle position/carb fuel delivery system is causing the fouling because you've used them all.
This is how I would proceed if it were my bike.... complete accurate series of plug chops at WOT, 2/3 throttle, 1/4 throttle, and idle.
We should see four groups of 4 plugs.  A plug color map of sorts.
WOT  1-2-3-4
2/3    1-2-3-4
1/4    1-2-3-4
idle    1-2-3-4

Then we can SEE what part of the carbs needs adjustment.

If ALL carb settings are equal (accurate vacuum sync + maintenance items included) AND...results from each plug chop group show fouling at #1, then we can move on to diagnosing a valve guide/oil issue.

[topperharley]

I was also thinking that i have 4 to 4 exhaust that i could go to an carburator shop and ask for a exhaust analys from cyl1. I think that is a good way too to get some info about mixture and exhaust fumes.

[flybox1]

I was also thinking that i have 4 to 4 exhaust that i could go to an carburator shop and ask for a exhaust analys from cyl1. I think that is a good way too to get some info about mixture and exhaust fumes.

This is the best option, but a dyno+gas analyzer is $$$ compared to plugs 

[Deltarider]

Not familiar with the 750, I don't know what type main jet is on yours. If it's the push in type, I advise to check if the O-ring around the jet is still good and seals well. If not, you'll have a rich running condition as the engine will happily suck in the extra fuel.

[topperharley]

I drove to work this morning about 12km. I took the plug out and it was looking the same as it did yesterday evening when i arrived home.
Yesterday i opened the air screw almost 2 rounds. It pops and backfires but doesnt get carbon on it. Search and experiments continues.

[flybox1]

I drove to work this morning about 12km. I took the plug out and it was looking the same as it did yesterday evening when i arrived home.
Yesterday i opened the air screw almost 2 rounds. It pops and backfires but doesnt get carbon on it. Search and experiments continues.

Until you isolate the throttle position which is causing the rich condition, you will continue to foul the plug riding around.  Stop turning the mixture screw.  Set them all the same(1.75 out) and get to some plug chops, man.  Lets get this figured out. 

[topperharley]

Yeah. You are right. What is purpose of the tube that connects carbs 1-2 and  3-4? 

Lähetetty minun SM-G903F laitteesta Tapatalkilla

[flybox1]

which one?  Picture?

[topperharley]

This is from 3-4 carb. Same one is on 1-2.





I allso wonder whats going on with this.


After bench sync the rods are univen. Carbs 1-2 are lower then 3-4. There is a 2mm gap on gliders to body on each carb.

[flybox1]

fuel delivery.

The other pics, with the slides at different heights, is ok.
its a result of vacuum tuning the individual carb slide heights to all pull the same vacuum.
it can be remedied, but its not an issue.

[topperharley]

Those pictures are right after bench sync. There is a 2mm gap on gliders to body on each carb. Vac sync not done yeat. Why the rods are in different level when gliders have the same position?