Hi...Intermittent spark on #4 at 4k

[Maxdog]

Hello from poor old bankrupt England!! I'm a new member of this forum and it seems like a mine of info - congrats!
My 99 Max was running very well on dynojetted carbs and a full Hindle system, until I noticed a slight backfire - not much but real annoying. I've cheked it out to #4 cyl. I changed the coil, the lead, plug and cap, checked connections - no luck. It is definatly an electrical prob as when I put a strobe on the H/T lead I get an intermittent blip, more pronounced as I get to 4k rpm then it goes. Could it be the cdi or pick up? The coil feed wire is white. :ummm:
Thanks
Maxdog.

 

[Akatora]

Hello,

Welcome to the forum!

Pick-up coil is possibly the fault. Better to measure the resistance from the connector. Connect the multimeter + to orange and - to black wire that are coming from the pick-up. The connector is under the saddle. The resistance value should be around 81...121 ohms at 20 degr. Celsius.

If the engine temperature has any influence (for example works ok when cold, problems begins when hot etc.), then take measurements when ok and again after the problem has occurred. This is because the (broken) pick-up coil wire may have contact when it's cold but get longer and loose contact when it gets hotter.

Hopefully you find a problem cause soon!

Cheers!

AT

 

[maleko89]

+1. Try switching the coil to the other side and see if the symptoms change sides too.

 

[Noxx72]

Coil over mod. Less money and time and no more digging those deeply buried coils out of the Max's packed innards anyway. Works very well with a stock CDI, and feel free to overgap your plugs a little (there's a significant voltage increase) for even more positive ignition. Lerv it.

 

[Maxdog]

Thanks for the info. Took the cover off and found that the p/up coil had a bit of damage. Looked like something had hit it and it was very close to the rota. I replaced it and all is now fine! One thing that puzzles me is ...how does this system work? there is only one p/up coil, 4 triggers and 4 plugs. How does the cdi distribute the sparks to the right cyl? I realise the system uses spare spark but that only answers half the question! You seem like a real tech bunch and once again ...thanks for your help. (My wife's just bought a V Rod) ....oh well

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