Spark plug question

[Denis Normandeau]

Ok guys, while bike was idling, I pulled the left spark plug cap off. Bikes rpm went down a little bit... put it back on, back to normal.
Then I pulled the right spark plug cap off, bike died...

Does this mean I’m running mainly on one spark plug?

 

[amc49]

Likely yes. You should be able to tell it in the idle quality.

 

[Denis Normandeau]

Dang, any suggestions on what I should do?
Plugs are new from beginning of the season...

 

[amc49]

Pull the plugs and compare them. What does the 'bad' one look like?

 

[Denis Normandeau]

Thanks for helping with this!
Pulled the plugs, here is the left side.

 

[Denis Normandeau]

Right side

 

[amc49]

What plug gap are you running there, it looks mighty wide but the pic angle messes that view up. Too wide a gap can kill spark.

 

[Denis Normandeau]

Measured the gap at 0.8mm

 

[amc49]

OEM gap is .6-.7 mm. Small bike coils are not well known for accepting going over OEM gap very far, set it to .6 with the problem you have now, it may help.

 

[Denis Normandeau]

Going to try that hopefully tomorrow and keep you posted, again thanks for the help!

 

[Denis Normandeau]

Re-gaped to .6mm, same problem.
Drove to the mechanic and as he was checking, he got a shock off the left side. Suggested we start by changing the spark plug caps and then work from there... we have ordered them and should know if it helps next week.

 

[xschris]

If your still using the iridium plugs make sure to use non-resistor caps.

 

[Denis Normandeau]

Ordered the non resistor caps, thanks!

 

[amc49]

While getting a shock can mean plug wires or other are bad it does not necessarily guarantee such, you can get shocked with brand new components.

And if the previously used plug was simply regapped to smaller it will still not fire, fouled plugs do not miraculously cure themselves in most cases. New plug. Once the foul short down the porcelain has been established it pretty much stays that way until destroyed by glassbeading or the like. Electricity always takes the easiest way, it will not go down the long road once the shorter one is present.

 

[William]

Ordered the non resistor caps, thanks!

Hi Denis,

Did you ever resolve this issues? I have the same problem

 

[Denis Normandeau]

We are still waiting on the parts... COVID seems to be slowing down the shipping to canada, I will keep you posted though!

 

[Denis Normandeau]

Long overdue update. Finally had the work done on the bike!

Yesterday they changed spark plug caps, did the valve timing, new air filters, new head gasket, lubed and cleaned too many things to list...
No more shocks, but problem is still there.
I pull the cap off of the left spark plug and the idle drops. Put the cap back on and pull the cap off of the right spark plug and the bike dies. Think I am going to grab some new spark plugs and go from there.

The good news is at cruising speed, I have definitely gained some passing power, I would guess from the valve timing.