1 and 3 cylinders not hitting.

[ZRice93]

hey everyone, I’ve recently bought an 85 vmax that sat in a guys garage for over a year.
I knew it wasn’t running right when I bought it so I’ve done some work so far.
new spark plugs, new oil, new gas, charged battery, and cleaned the carbs.
After all that it runs! Just not well.
After some testing I’ve found that cylinders 1 and 3 aren’t getting a spark at all. Based on my tester they are dead in that water (but get a spark after turning the ignition off).
I’ve read through a few posts from users that have had a similar/exact same issue. But all of them seem to end without any sort of confirmed fix.
So please, if anyone knows why this is happening and how to fix it I’d really appreciate it.

 

[Fire-medic]

1&3 are the rears, check the pilot jets. I suspect they may be plugged. Also check the gas tank and your fuel filter.

 

[ZRice93]

1&3 are the rears, check the pilot jets. I suspect they may be plugged. Also check the gas tank and your fuel filter.

The cylinders are getting gas fine. There’s just no spark hitting them.

 

[maleko89]

Check p/u coils. There are two, one for front cylinders and one for rears. Unfortunately they must be replaced as a set. The plugs will fire when key is turned on and again when off. That’s normal and happens regardless of p/u coil condition.

 

[ZRice93]

Check p/u coils. There are two, one for front cylinders and one for rears. Unfortunately they must be replaced as a set. The plugs will fire when key is turned on and again when off. That’s normal and happens regardless of p/u coil condition.

Okay I’ll check them tomorrow and report back with what I find, thank you!

 

[one2dmax]

Could be the pickup coils but the most likely issue is a bad CDI box. Check those pickups first though.

 

[ZRice93]

Could be the pickup coils but the most likely issue is a bad CDI box. Check those pickups first though.

Yeah my original thought was a bad CDI box. But I wanted to make sure there wasn’t something simple I was maybe missing
EDIT: Correct me if I’m wrong but if the CDI box was bad wouldn’t that cause all 4 cylinders to not spark? That’s really the only thing stopping me from ordering one.

 

[MaxMidnight]

Yeah my original thought was a bad CDI box. But I wanted to make sure there wasn’t something simple I was maybe missing
EDIT: Correct me if I’m wrong but if the CDI box was bad wouldn’t that cause all 4 cylinders to not spark? That’s really the only thing stopping me from ordering one.

Listen to Sean, he is giving good advice.

 

[likembikem]

Sean is ‘one2dmax’

 

[ZRice93]

Well it’s looking like P/U coils could be my issue. I’m going to change them before getting a CDI box.
does anyone have an recommendations on where I could find them?

 

[Fire-medic]

Try Sean Morley [email protected] for a used one. '85-'89 use a double pulse sensor, 1990-'07 use a single pulse sensor (pick-up coil). The old ones are expensive from Yamaha. You can switch to a different style (replace the old system with the new system) but that is time-consuming and pricey as you need a different rotor, wire harness, ignition CDI box and pick-up coil. There are threads on doing that, use the search function.

 

[MaxMidnight]

Well it’s looking like P/U coils could be my issue. I’m going to change them before getting a CDI box.
does anyone have an recommendations on where I could find them?

You say the p/u coils MAY the issue. Have you been able to confirm this?
IMO it is better to confirm your theory by getting some facts, i.e. resistance reading and visual inspection.
Without this you may well be pissing money down the drain needlessly.

 

[ZRice93]

You say the p/u coils MAY the issue. Have you been able to confirm this?
IMO it is better to confirm your theory by getting some facts, i.e. resistance reading and visual inspection.
Without this you may well be pissing money down the drain needlessly.

You’re 100% correct. I’m new to all of this and still trying to figure stuff out, I’ve had my FIL come help me look at it and I’ve spoken to a couple different people on the subject. The general consensus is bad CDI box. But I’m not really sure how to test that without having a second one

 

[maleko89]

Resistance test isn't always 100% to determine good or bad p/u coil. A small handheld oscilloscope is helpful seeing the signal from p/u to ignitor and from ignitor to primary coils. Or, if you have an aftermarket ignition unit, you can see p/u signals being registered.... with an LED light on Dyna3K or using laptop for Ignitech.

 

[Creepshow]

Resistance test isn't always 100% to determine good or bad p/u coil. A small handheld oscilloscope is helpful seeing the signal from p/u to ignitor and from ignitor to primary coils. Or, if you have an aftermarket ignition unit, you can see p/u signals being registered.... with an LED light on Dyna3K or

You’re 100% correct. I’m new to all of this and still trying to figure stuff out, I’ve had my FIL come help me look at it and I’ve spoken to a couple different people on the subject. The general consensus is bad CDI box. But I’m not really sure how to test that without having a second one

Hello, curious if any update here? I am running into a similar issue with my 1990 Vmax.