Source coil rewinding

[Echo guy]

Hello, i have an echo 610evl chainsaw, its a twin cylinder chainsaw utilizing two coils and one pickup coil, the pickup coil has a cdi box to automaticaly advance the spark. My question is can i delete the cdi box rewind the pickup and wire it in? If so would i rewind the pickup in the standard way? Idk how it was, the pickup and cdi were potted together in epoxy

 

[Diver300]

You can't delete the CDI box.

All ignition systems have to have something to trigger the spark. On old contact-breaker ignition systems it was the contacts opening the caused the spark. Power from the pickup coil (or the battery) would build up current in the ignition coil and that current would be interrupted very quickly by the contact opening. The spark happens when that current is rapidly interrupted.

On CDI systems, the capacitor is charged up from the pickup coil, and then the electronics will connect the capacitor to the ignition coil, and that is when the spark happens.

You need something that detects the correct position of the crankshaft, and at that time it releases the stored energy (stored as current in the ignition coil or as voltage in the capacitor) into the spark.

 

[Nigel Goodwin]

You can't delete the CDI box.

All ignition systems have to have something to trigger the spark. On old contact-breaker ignition systems it was the contacts opening the caused the spark. Power from the pickup coil (or the battery) would build up current in the ignition coil and that current would be interrupted very quickly by the contact opening. The spark happens when that current is rapidly interrupted.

On CDI systems, the capacitor is charged up from the pickup coil, and then the electronics will connect the capacitor to the ignition coil, and that is when the spark happens.

You need something that detects the correct position of the crankshaft, and at that time it releases the stored energy (stored as current in the ignition coil or as voltage in the capacitor) into the spark.

The older engines used points, and an ignition coil, both inside the spinning magnetic drum (along with alternator coils for the lights - on a motorbike at least) - so actually generated a far higher voltage in the coil, rather than using a low voltage coil followed by an external ignition coil. As I'm sure most people here know, those system were extremely unreliable, and often were difficult to start.

As kids, building bikes up to ride in the fields, our solution was to remove the internal coil and run a wire out from the points. We'd then add a 6V battery, an external ignition coil, and a toggle switch to turn it ON and OFF. This massively improved starting reliability, and we just charged the battery once a week or so - interestingly, as the battery started to go flat, you would get a lower and lower revving engine.

 

[Diver300]

interestingly, as the battery started to go flat, you would get a lower and lower revving engine.

I think that with a lower voltage and higher impedance of the flat battery, the points need to be closed for longer to get to enough current for a spark.

 

[Echo guy]

Thank you for the explination that makes a lot of sense, I still have the cdi box it wasnt damaged when i seperated the coil, in theory i could free it from the holding material using acetone, repair any open solder joints and rewire everything back together? I have seen youtube videos where they repair the cdi box, and ones where fhey rewind source coils. Ill post pictures of the contraption later today.

 

[Echo guy]

 

[Nigel Goodwin]

Don't know if this old story will help at all?, but back in 1976 I bought a brand new Yamaha RD400 trail bike - I got someone from work to give me a lift at dinner time to the dealer to collect it, and rode it back to work. By the time I got back to work it was running a little rough, but I presumed it was just because it was new, so carried on working. When we finished work I couldn't start the bike - it just kicked back (it was a 400cc single cylinder two stroke), and it was like someone hitting the sole of your foot with a hammer - REALLY painful. So I stuck the bike in the garage at work, and made my way home somehow?.

The dealer was closed by this time, so I rang them first thing the next morning, and they arranged for someone to come out - and they were coming about 1:00pm. So a little while before 1:00 I got the bike out of the garage ready for them, and one of my workmates Paul asked what was wrong with it - so I explained the problem, and offered him a try to start it (knowing that it was seriously painful ). Anyway, he kicks it and it started - so I went a quick ride round and it was working fine. I'd just got back and the guy from the dealer turned up, with an empty bike trailer on the back of his car.

So he came across and asked what the problem was, so I said it won't start - sat on a running bike - so he took it for a ride and came back saying he couldn't find anything wrong with it, so to try it again and see how it goes. He got off the bike and walked towards his car, and I got on the bike and it stalled when I tried to set off - he turned round and looked at me, and you could read from his body language what he was thinking

I tried to restart it, and it was kicking back again - so he came across and tried himself - needless to say it wouldn't start, and by the time he'd finished he could hardly walk. So he put it on the trailer, and took it away.

As they were unable to repair it with in a couple of days they lend me a bike, and when I went to collect it, I noticed that every member of staff was limping? - perhaps no coincidence I thought?.

Anyway - back to the reason for this long story.

They replace the CDI unit, and it didn't cure it - and eventually Yamaha themselves sent an engineer out, and he replaced the coils under the flywheel - this cured the problem. Later on the same year, while still under warranty, the same thing happened again - this time the dealer fixed it themselves, but never actually mentioned what had been done to cure it.

I ran the bike for a few years, never had any more problems with it, then sold it to a friend when I bought a car - he in turn sold it to another of our friends, and I eventually bought it back and ran it a further few years. However, both of my friends who had it replaced the CDI unit at least once - but again, I had no issues while I had it. I eventually sold it to another friend, who in fact I now work with - I'm not sure who he sold it to.

So issues could be the CDI unit, or the coils, or both - but there's nothing you can do without both of them working correctly.

I presume you can't just buy new parts at a reasonable cost?.

 

[Echo guy]

Every story helps one way or another im sure its the pickup coil/cdi unit as i swapped it out from another saw just to be sure.

 

[Nigel Goodwin]

Every story helps one way or another im sure its the pickup coil/cdi unit as i swapped it out from another saw just to be sure.

That's always the best way - I've just done a quick google, and I see that many of the spares (such as the ones you need) are obsolete

 

[Echo guy]

They are nowhere to be found and its a common problem for these saws unfortunately, being a rare twin cylinder saw itd be cool to get a repair procedure or something out there

 

[Nigel Goodwin]

They are nowhere to be found and its a common problem for these saws unfortunately, being a rare twin cylinder saw itd be cool to get a repair procedure or something out there

I thought that sounded unusual?, it's been many decades since I last used a chainsaw (I was still at school) - but I don't recall them been twin cylinder.