Tach and 2 cylinders dead when hot

[Fire-medic]

Just like with old Mopar muscle cars with stock type electronic ignition, always keep a spare box with you.

"Change-out the firewall-mount ignition module when you notice the goo running-down your firewall from the back of the ignition module." There should be a sticky metallic tape with this on it, next-to the ignition module. It was not-only the muscle cars.

 

[Coastal Grey]

Just like with old Mopar muscle cars with stock type electronic ignition, always keep a spare box with you.

Oh the joy of ballast resistors my dart would puke one all the time kept a few in the glove box

 

[Fire-medic]

Oh the joy of ballast resistors my dart would puke one all the time kept a few in the glove box

I forgot about those, it could be the ceramic coiled-wire candybar, or it could be the melting ignition module, both next to each other on the firewall.

 

[pfeutim]

Hi Jack,
many thanks for your lines.
I fact I'm waiting to the pick up sensor arriving.
What I additionally did and not wrote above is, that I cleaned all dozens of connectors with spray and connected back 2-3 times to remove any oxidation.
The connector of the pick up I even made new, as my fear is there.

Also I can say, that my problem started slowly and is getting worse over a month now. Firstly the vmax pushes/pulls just a little bit in the partial load range. Then it start with pretty hard and short power holes and now I'm on the stage, that the bike even stops or does hardly react on the throttle.

The thing I wonder really is, most of the cases when this happends, I only have to press the clutch, wait until I'm on 1krpm then everything works again for a while. This leads to me to a chaos in the Cdi (possibly and hopefully comming from the pick up miss signaling)

in the meantime I received the Pickup and replaced it, but the problems still persists. I will go now to look on a new Cdi.
What you recon: the Dynatech 3000 or the Ignitech CDI with Vboost Control Capability, which Sean sells?

 

[Creepshow]

in the meantime I received the Pickup and replaced it, but the problems still persists. I will go now to look on a new Cdi.
What you recon: the Dynatech 3000 or the Ignitech CDI with Vboost Control Capability, which Sean sells?

I am having a similar issue and would like to hear how the new CDI works for you.

 

[Sniffbooger]

I didn't get a chance to look at my issue this weekend, it was too hot, extreme heat advisory so I tried to stay inside and stay cool...but I rode my Vmax to work today like usual, and it was fine, until I came home it suddenly died on two cylinders and backfired loudly...I pulled over to the side of the road and turned off the key, then restarted it...and it was fine.. got home with no more issues ...this is a random thing. Very strange...

 

[Creepshow]

I didn't get a chance to look at my issue this weekend, it was too hot, extreme heat advisory so I tried to stay inside and stay cool...but I rode my Vmax to work today like usual, and it was fine, until I came home it suddenly died on two cylinders and backfired loudly...I pulled over to the side of the road and turned off the key, then restarted it...and it was fine.. got home with no more issues ...this is a random thing. Very strange...

I’ve had the same thing off and on for the last month. Checked all connectors and cleaned them up to shiny metal and also found a small hole in the old vacuum line which leads to vacuum sensor, replaced that as well. Seemed to do the trick and for the past week ran great but going into work today it started back up, only after about 20 minutes of riding and once engine up to operating temp. Today all of a sudden my headlight and instrument cluster light both went out when I engaged my clutch as well and won’t come back on. Need a full day off to investigate deeper. Tested Pick up coil while hot and just a bit higher than spec. Thinking it’s CDI.

 

[02GF74]

Need a full day off to investigate deeper. Tested Pick up coil while hot and just a bit higher than spec.

Metals have a positive coefficient of resistance, ie the resistance increases with temperature.
Household light bulb blow when switched on since a that moment their resistance is lowest drawing the larges current.

 

[MaxMidnight]

Metals have a positive coefficient of resistance, ie the resistance increases with temperature.

True, but if we are talking about changes in ambient temperature is the difference going to be significant?

 

[02GF74]

True, but if we are talking about changes in ambient temperature is the difference going to be significant?

Dunno without further investigation.

The manual states pick up coil resistance at 20 c.
There probably is some variance in manufacturing.

The OP's coil may be one at the top end of the resistance, factor in the temperature increase so would explain: Tested Pick up coil while hot and just a bit higher than spec.

 

[MaxMidnight]

From what I have read the change per degree is very small so unlikely to make a difference?
If you want another pebble to throw into the pond then the resistance of carbon and silicon decreases as temperature rises.
Temperature related breakdown of insulation might be more likely?

 

[Jack Hammer]

Factory parts in vehicles have quite a broad spectrum in the operating range. If your readings are slightly off, doubt that's the case.

 

[Sniffbooger]

UPDATE: I didn't have a chance to dig into the issue and check some things like I had planned last weekend, due to the nasty hot weekend temps and oppressive humidity...but I have been riding my Vmax to work daily all this week, 18 miles each way city/hwy. Only a couple times it gave me an issue on the drive, with backfiring and loss of power, but it cleared right up as soon as I turned of the ignition key and turned it back on. Restarted and ran fine with no issues after that. This is an intermittent issue, and I thought it was heat related, but this morning it happened when I started it up cold. It was missing, backfiring loudly like a shotgun, dead tachometer, and would not rev more than a couple hundred RPMS. So I turned it off with the key, restarted it and no problem all the way to work. This is something I still have to spend more time diagnosing. I know the rear two coils under the seat have cracks on the bottom side, but I have not been able to inspect the front coils yet. Not sure if this is part of the issue, but I will silicone them and seal them up soon. I am really considering that DB Electrical CDI box for $150 on Amazon...

 

[Fire-medic]

This is what I found from your named company: https://www.amazon.com/Electrical-IYA6055-3JP-82305-11-00-3JP-82305-12-00-3JP-82305-13-00/dp/B01NCUTI4Q/ref=sr_1_28?crid=333DQWJB9IFWK&keywords=db+electrical+cdi+box+yamaha+vmax+2007&qid=1663205512&sprefix=db+electrical+cdi+box+yamaha+vmax+2007,aps,72&sr=8-28

$149.87 w/free delivery amazon prime.

I didn't compare it to the service manual for the model # but you may want to. http://vmoa.net/VMX12-Service-Manual01.pdf

I'd buy a DYNA ignition, or an Ignitech, though you would spend more $.

If the coils pass all the tests in the service manual, I wouldn't worry about the cracks. They can have surface cracks and it doesn't affect their operation. If you want to fill the cracks with JB Weld or something, it can't hurt.

Again, (for those other than the O.P. who has included his bike year) if you include your year of bike and any mods in your signature line, it can help someone giving you advice to know which bike you have and its mods. It saves hunting backwards to discover which/what/where.

 

[02GF74]

UPDATE: . it cleared right up as soon as I turned of the ignition key and turned it back on. This is an intermittent issue, and I thought it was heat related, but this morning it happened when I started it up cold. So I turned it off with the key, restarted it and no problem all the way to work.

The fact it clears up after a power off/on would indicate to me it is an electrical component that runs erratically and is then reset after a power cycle.

The vboost unit goes through an initialisation sequence and probably with the ignition unit.

Before spending cash on an ignition unit, maybe worth unplugging the vboost unit to see if the problem stops.

 

[pfeutim]

I am having a similar issue and would like to hear how the new CDI works for you.

Hi, I received the Ignitech and my bike is running now again since approx 2 month of seeking and searching for the problem. The bike is also running far better as ever. My feeling.

 

[Fire-medic]

Good, glad it's fixed. These bikes are lots of fun when they are running properly

 

[pfeutim]

Hi everyone,

Following up on this thread:

As some of you might recall, my VMax has been running with a new rotor coil and an Ignitec from Sean for the past two/three seasons. However, this year I’ve noticed an issue across all four cylinders—some worse than others—where the spark is jumping from the spark plug cap to the engine instead of firing at the spark plug end in the cylinder.

My current setup is as follows:

• Spark Plug Cap: NGK SD-05 F (5kOhm)
• Spark Plug: DP-8 EA-9 (non-resistor type)
• All new silicone ignition cables

Here's what I've tried:

I reduced the spark plug gap down to 0.4mm (0.015"), which I know is far too small, but the engine fires more consistently at this setting. When I open the gap back up to the recommended 0.7-0.8mm (0.027-0.031"), I can see visible sparks in the dark, jumping from the NGK SD-05 F cap to the cylinder head.

My question is: What can be done to maintain the correct 0.7mm gap without these stray sparks occurring?
I see arc of many mm (~10mm / ~0.39-inches.)

The rotor I replaced two years ago produces more power, likely generating higher voltage. My concern is that the increased coil output might be too high for the insulation to handle, leading to this issue.

Any ideas or suggestions would be greatly appreciated!

 

[Fire-medic]

By 'rotor coil' I assume you are referring to the engine stator, on the left side at the crankshaft?

https://ia800204.us.archive.org/14/...ice-manual/yamahavmaxvmx12-service-manual.pdf

See p. 328 of 405pp of the .pdf page count, of the factory service manual.


Minimum gap: .024 inches.

 

[pfeutim]

Hi Fire-medic

yes I meant the engine sta
tor.
I'm waiting to a tool for the spark measurement and will come back with my results.

Meanwhile I show you on a video of my problem.View attachment vlc-record-2024-08-19-23h16m10s-2024-08-08 21.28.45.mp4-.mp4