spark?

[golden763]

ok im haveing a problem at idle my vmax only sparks on 2 cylinders but the minute it gets over like 1500 rpm it starts to spark on all of them whats up with that? thanks for the help

 

[maleko89]

What's the Ohm reading when you measure from the plug cap boot to frame ground?

 

[golden763]

What's the Ohm reading when you measure from the plug cap boot to frame ground?

im not sure i can check that later though from the boot or the pat that clips on the top of the saprk plug? and about what should it be

 

[maleko89]

The metal piece that's up in the boot. It should be 19 - 22 KOhms. Wiggle the wire while measuring and make sure it stays consistent. While you are at it measure the Ohms of the pickup coils too. That should be about 110 Ohms.

 

[one2dmax]

What year is the bike? We've had a few lately that are 85-89's doing that same thing and replacing the CDI has fixed it.

Sean

 

[vmaxman99]

You could be leaking spark somewhere at the lower RPMS. Run the bike in the dark and look/listen for arcing. Seen this happen on mine, replaced wires, fixed it.

 

[vmaxman99]

The ignition box could be the problem, but of what I know of electronics (17+ years of experience), the transistors in the box will either work or not work at all. RPM shouldn't make a difference, but I suppose anything is possible.

 

[Rusty McNeil]

The ignition box could be the problem, but of what I know of electronics (17+ years of experience), the transistors in the box will either work or not work at all. RPM shouldn't make a difference, but I suppose anything is possible.

Correct.

When transistors fail they fail shorted, and stay that way, usually.

But the gate circuit that turns them on can fail intermittently I think

When my TCI went it did so intermittently and it seemed to be heat related, I did all the easy stuff; replacing coils wires, plugs, and checking the pickups.

When I gave in and bought a Dyna 3000 it fixed the problem.

Rusty

 

[one2dmax]

I've got one I just swapped out last weekend. At idle the bike sounded like a shotgun going off ever few seconds. Bring the rpm up and the bike would smooth out and pick up the cylinder. Swapped it with a dyna (and stock TCI) and problem went away.

Sean

 

[vmaxman99]

Rusty, the ignition box can be repaired. Sometimes it's only a cold solder joint.

 

[vmaxman99]

Sean, isn't electronic stuff great?!

 

[Rusty McNeil]

Rusty, the ignition box can be repaired. Sometimes it's only a cold solder joint.

Yeah, I took mine apart and checked the transistors, didodes and looked for any obvious visual stuff but didn't see anything. I wanted the rev limiter the Dyna provides anyway so went with it.

I've seen where RMSportmax will repair any TCI for around $100 I believe.

Still have my old one if it ever comes up.

Rusty

 

[Akatora]

ok im haveing a problem at idle my vmax only sparks on 2 cylinders but the minute it gets over like 1500 rpm it starts to spark on all of them whats up with that? thanks for the help

It is good idea to check also the resistances in the ignition pick-up coil wiring. This is very quick and easy operation to conduct. The connector is located under the saddle, and the wiring is coming from the alternator side there. Depending on the year model there are either 5 pins or 2 pins in this connector. If 5 pin connector, check the resistance between black wire and all the others one by one (on the flywheel side of the connector). The value should be between 96 and 126 ohms in each at 20 degr. Celsius. If you have two pin connector, just check the resistance between those 2. The resistance value should be between 81 and 121 ohms at 20 degr.

The older model has two ignition pick-up coils around the flywheel so that one is giving pulses to TCI for cylinders 1 and 3 (rear), and the other gives the pulses to TCI for cylinders 2 and 4 (front). If one of those pick-up coils is failing, it could cause two cylinders not to fire.