Suddenly decides its not going to run!!!

[Yammaman]

Hi, looking for a little advice here, rebuilding a barn find 2MA for the last year and has been going ok, been my everyday ride for the last few weeks and has been running well, not perfect as the power valve is not functioning, control unit is being repaired in Greece.
Last ride it was running fine, I picked up some new plugs BR9ES and fitted them, old ones looked fine and were resistor plugs.. today went to go to the bike meet and started first kick as always, rode off and it pretty instantly lost power and stopped, started again but would not rev, took it home and checked fuel, is good, fuel level in carbs is good, dropped the bottoms off, nothing wrong.. It still starts but won't rev, the plugs are wet, im thinking the 36 year old coil has failed.
I have read on here that the ignition system is not great, this is going to be a road bike with occasional track use so here is where I ask your advice, firstly am I missing something, secondly any recommendations on a coil, Dyna coil is coming up, Moto Legends have a coil for half that money or is there another that would be a good contender.. Thanks in advance..

[teezer250]

I would buy a genuine Yamaha coil so you know it's correct.
The primary and secondary resistance values have to be right for a non-standard coil such as Dyna and aftermarket ones.

I would also check the battery and reg/rec are working fine too along with checking earth lead from battery.
These can lead to poor running.

[m in sc]

id def look at the coil. its nothing really special. i have the dyna on mine as a preventative maintenance mod because i was leery on running an, as you say, 36 year old coil. tbh, most any twin lead cdi coil will work if the resistance is correct.  even if its just for testing.  .02

[Yammaman]

Thanks for the input, not sure where I can get a genuine Yam one but worth a look, maybe Yambits, battery is new and the charging is good, fortunately I have a borrowed coil on its way so ill know for sure in a couple of days...

[biggz]

i have the dyna on mine as a preventative maintenance mod because i was leery on running an, as you say, 36 year old coil. tbh, most any twin lead cdi coil will work if the resistance is correct.  even if its just for testing.

Hi, Which Dyna coil have you fitted? Reason I ask is that the UK product list doesn't look to have anything at 0.26~0.40ohm/4.7~7.0kohm rating. (You can tell electrics aren't my thing.)
Thanks
Laurie

[SP_BOTT]

I've fitted a couple of Dyna-mini coils to various Yamahas, or the bigger Blue coils, think they are around 0.5 Ohms. Like this one.

https://www.ebay.co.uk/itm/256123241679?hash=item3ba22284cf:g:w6wAAOSw7q5kmxDG&amdata=enc%3AAQAIAAAA4KqjjSAw%2FXa%2FIPCfHDUSJ9HztimwfYoHtsmkNigVFvveatlscoM8h0gWmkIb%2BQ6yCAPFJhH40KqtgxMROUk6yWpIJ9zMygmRkaV3bkEfCsFmmATd2WrkBQWi1hELYgoNvncsatp96JltV%2B4WipKXQCc5w87UkjiCYW4bf8ph1NWYhPioRb5suvUPTeB4yQ%2Fi9Z9nd6e7bia2UIjD3osI1v8Rx00mOy0AGSYJobParL8pLDuc%2BAQCP7BKH2GgmTTDwHKYCcpY4Ku1Kdh%2BhLQOB%2FctONfDTKKEkSljdjv8itcJ%7Ctkp%3ABk9SR8yXvtu8Yg

[m in sc]

^ thats what i have on mine.

[biggz]

Got it, looks like a DC11-1 https://shop.dynatekuk.com/dc11-1-453-p.asp
(I was looking in the wrong place.)

Thanks, Laurie