Yamaha 55 working on one cylinder

[P1]

Hi to all i have Yamaha 55 year 1995 2cly it seems that is working on one cylinder i arrived to that because first i unpluged spark plug cap number 1 and the motor stoped than unpluged spark plug cap number 2 and the motor still run the same.Can some one tell me please if it is Coil or CDI fault or can i do a test of the coil and cdi.

Thank you and help be very apriciated regards P1.

 

[rodbolt]

Re: Yamaha 55 working on one cylinder

unplugging a spark plug wire is useless at best and usually stupid.
like I posted before, make a spark tester and TEST it. if it sparks ok then its compression or lack of fuel.

 

[99yam40]

Re: Yamaha 55 working on one cylinder

Check compression and spark on all cylinders.
If they are good the look at the fuel. Carbs

 

[P1]

Re: Yamaha 55 working on one cylinder

I tried with spark tester on cylinder 1 spark is ok but on cylinder 2 some times it spark and some time not.Fuel is coming on plug.

Thank you for your help and regards P1.

 

[P1]

Re: Yamaha 55 working on one cylinder

I have tried a test right now this is the result

Coil 1 with spark plug 1 bright light on tester
Coil 1 with spark plug 2 bright light on tester
Coil 2 with spark plug 1 dimm light on tester
Coil 2 with spark plug 2 dimm light on tester


Coil 1 with spark plug 1 spark on tester ok but Coil 2 on spark plug 2 with 5 key turning 3 spark 2 not on tester.

Thank you and regards P1 your help is very appriciated.

 

[rodbolt]

Re: Yamaha 55 working on one cylinder

use a spark tester capeable of a 7/16th" gap. you dont use the tester with the spark plug in the circuit.
if a plug wire has no spark test the CDI output voltage and the trigger coil inputs.

 

[P1]

Re: Yamaha 55 working on one cylinder

First thank you for your help so if i understand well i have to remove the plug from the engine and with the gap set to 1mm see if the plug pass spark.

Thank you and regards P1

 

[rodbolt]

Re: Yamaha 55 working on one cylinder

do a forum search, key word,home made spark tester.
plugs out,tester in place, gap is .437 thousands of an inch.
roughly 11mm.

 

[GoogieMan]

Re: Yamaha 55 working on one cylinder

unplugging a spark plug wire is useless at best and usually stupid.
like I posted before, make a spark tester and TEST it. if it sparks ok then its compression or lack of fuel.

i lost spark to NO.3 on my 140 yam turned out to be the male plug on the wire that connects the CDI to the coil pack, light sand and away she went, so theres another possibility

 

[P1]

Re: Yamaha 55 working on one cylinder

Hi thank you for your help but i sand all the bullets connectors in hole motor and i have put petrolum jelly on.Can any one tell me how to check the CDI please or Coil with volt meter.

Thank you your help very appriciated regards P1.