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Strimmer Engine CDI conversion,which Spark Plug

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Old 01-25-2013, 05:04 AM
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GSXRMAN2010
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Default Strimmer Engine CDI conversion,which Spark Plug

Hi Guy's I'm new to the forum,I been flying elecrtic and glowon and off for the past 3/4 years.I recently came across 2 smallgrass strimmers whichI stripped out andused 1 for a while with the magneto ignition.After a while I decided to change to CDI ignition to save weight but I've come across a problem.
Ifirst bought a CRRC unit which was working I had spark and the engine runfor a few seconds then cut and would't start again (I wasn't getting spark) Oh btw I was using the original plug that came with the engine (Champion RDJ8J)..Sometime later I decidedto have another go using an RCXEL unit,with the same results..
I suspect it's the spak plug thats the problem (something to do with resistance ??) but I'm not sure..

Can anyone shed some light as to what plug I should be using,it has to be 14mm thread and short reach..

Any help is appreciated..Mike P.S. The engine isabout 18/20 cc
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Old 01-25-2013, 05:15 AM
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Default RE: Strimmer Engine CDI conversion,which Spark Plug

If the ignition can not spark normally through the spark plug, it will fire inside the sensor or even the ignition unit destroying it. Something is not correct about your circuitry?

Forget the CRRC unit. Thy went bad all the time for small wire that break,
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Old 01-25-2013, 05:32 AM
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Default RE: Strimmer Engine CDI conversion,which Spark Plug



Hi Thanks for your reply..
As far as I'm aware the circuitry is correct..I had no problem with getting spark until it run for a few seconds..

One thing I noticed was sometimes I could see it spark at the hall sensor just like you said.

Irecall someone telling me that not all spark plugs are the same,some have resistance and some don't but I'mnot that technicaly minded,I wouldn't know the difference...
After a bit of fishingabout onthe net Ibought a newplug (NGK CM6)thinking all would be ok butthe tread size is to small so what Ineed is something similarbutwith a 14mm thread..

Mike

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Old 01-25-2013, 05:49 AM
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Default RE: Strimmer Engine CDI conversion,which Spark Plug

NGK BPMR6A for a 3/4 hex plug cap
NGK BPMR6F for a 5/8 hex plug cap

Milton
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Old 01-25-2013, 06:01 AM
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Default RE: Strimmer Engine CDI conversion,which Spark Plug

sparking at the sensor means the plug cap wasn't grounded properly, this will fry the sensor after a few seconds and then no more spark...

by default i think most of these ignitions come with a cap designed for the CM-6 unless you specify otherwise. if you tried to use this kind of cap with an RDJ8J (5/8" hex taper seat) it would fit on and make contact at the top of the plug just fine but would not ground against the base of the plug like it should.....look at the various sites selling ignition and parts to see how these caps should fit. and if this is indeed what happened then you should probably be OK if you get the correct plug cap kit and a new hall sensor.
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Old 01-25-2013, 06:06 AM
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Default RE: Strimmer Engine CDI conversion,which Spark Plug

and concerning resistor plugs...the little CM-6 is not available with resistor so the caps have one built in. the larger plugs are available with built in resistor so the caps for them don't need any added resistance. the "R" in RDJ8J means it is the resistor type.
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Old 01-25-2013, 06:11 AM
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Default RE: Strimmer Engine CDI conversion,which Spark Plug

Look at the instruction sheet below.

Milton
Attached Files
File Type: pdf
Rp43109.pdf (282.8 KB, 15 views)
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Old 01-25-2013, 08:43 AM
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Default RE: Strimmer Engine CDI conversion,which Spark Plug

Thanks ZAGNUT and BadAzzMax...

Ithink you may wellbe spot on with your comments regarding the plugbeing grounded Zagnut....So assuming the unit is ok but the hall sensor is now "fried"I will try it outsoon and repost my findings..

Thanks Milton for providingthe attachment and plug codes...

Iappreciate your help verymuch guys

Mike
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Old 01-25-2013, 08:57 AM
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Default RE: Strimmer Engine CDI conversion,which Spark Plug

There are several places that carry's plug adapters that will allow the use of a CM6 plug in 14 mm plug hole. Here is just one such source.
http://www.agaperacingandhobby.com/ Look under ignitions, they also carry new hall sensors and other parts individually.
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Old 01-25-2013, 09:08 AM
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Default RE: Strimmer Engine CDI conversion,which Spark Plug


Quote:
ORIGINAL: GSXRMAN2010

Thanks ZAGNUT and BadAzzMax...

I think you may well be spot on with your comments regarding the plug being grounded Zagnut....So assuming the unit is ok but the hall sensor is now ''fried'' I will try it out soon and repost my findings..

Thanks Milton for providing the attachment and plug codes...

I appreciate your help very much guys

Mike
Shipping cost for the small parts would exceed the cost of the products.

Check with Paul at www.gashanger.com He is in the UK and might have what you need.

Milton
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Old 01-25-2013, 11:59 AM
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Default RE: Strimmer Engine CDI conversion,which Spark Plug

instead of an adapter for the CM-6 i would get the correct plug cap for the plug you have. price is pretty much the same either way but the larger plug is more durable and less prone to fouling and the cap will be more reliable as well.

here's some plugs that will work:
http://www.gsparkplug.com/shop/spark...12&resistor=65

http://www.gsparkplug.com/shop/spark...30&resistor=65

the ones with Y or P in the part number have projected tips and might not work in your small engine.

also notice that the champion brand (denso as well) has a 8.3mm reach while the NGKs have a 9.5mm reach...in reality they are the same, NGK measures from the top of the taper seat while the others measure from the bottom...
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Old 01-30-2013, 11:22 AM
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Default RE: Strimmer Engine CDI conversion,which Spark Plug



Thanks very much guy's for your help..

I fitted a new spark plug (BPMR6F)today along with a new hall sensor and after a little fettling about with the mixture screw the engine runs..The CDI unit is fine and appears to be working well...It starts first time by hand but I won't be doing that to often !!

The only minus I can see at the momment is it seems a little laboured so I may purchase another prop.I'm running it with a 16-8 atm so maybe a 16-6 will help..

Anyway a BIG thanks to you all for your help !!!!!!!!

MIKE

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