Yamaha 50D Strange fitting

[avonsearider]

When you mentioned Voltages I realised you would be referring to the later 50V manual for America which I also have a copy of.
I have a European 50D model and the Factory Service Manual 6H428197-G1 that asks for the readings in Ohms.
As and when the later manual for the 50V asks for Ohms values they are different to those found in the 50D manual.
Any replacement parts are specific to the earlier 50D (you can see the CDI in the manual has a different layout).
I also used an inline spark tester and the bulb was very dim and only visible with the lights off in an enclosed building.

Has anybody had any issues with the parts form China?

[boscoe99]

The ohms values are not as important as output voltages.

[panasonic]

I find it hard to believe that you are finding pretty much all of your ignition system components out of spec. You probably have the wrong specifications. As mentioned already peak measurements are the way to go to trouble shoot your ignition components. Here is the adapter I have to do this.

https://www.amazon.ca/Voltage-Readin.../dp/B00R3B6HYW

[panasonic]

You should be able to find the peak voltage specification here.

https://www.cdielectronics.com/

[boscoe99]

Is the complete engine ID not known?

A 50D was not distributed here in the US. If the complete ID was known we can get to the US equivalent model.

[boscoe99]

Found your engine ID. Buried in my messages.

Looks to be a 1991 model year motor.

Here is some info that might help.

[avonsearider]

Thankyou for the reply. What was the image of?

[avonsearider]

According to a CDI professional, this is a sign of moisture entering through the advance/retard lever.

[ArjanStam]

Hi avonsearider,

is it possible to share the service manual?

I have a Yamaha 40HEO, with similar problems which I was able to solve last weekend.
motor would idle rough for 20 seconds, than die. Or if try to rev up it would die.

I suspected the CDI, because idle timing was 6 degrees btdc instead of 6 degrees atdc according manual. however, this is part of the high idle circuit, after 20 seconds the timing changes from 6 degrees btdc to 6 degrees atdc. and my motor would stall.
I only managed to let the motor run with idle screws 2,5 turns out. And run at higher rpm by spraying additional fuel randomly in 1 of the 3 carbs.
disconnecting the cdi wiper arm made it easier to let the motor run.

However, after lot of searching and the 3rd time disassembling the carbs, I found that idle jet no.23 (6H4-14948-11) under the rubber cap was not fully clean in length direction.
and if you have a prime solenoid on the bottom carb, you should check the diaphragm no.43 (6H5-2411-00) in showed some cracks, causing a fuel/air leak.

after cleaning and replacing the jets again, and replacing the leaking diaphragm, I properly synced the carbs and now it runs better than ever. After it was running again, I adjusted the timing to be exactly according spec.
Good luck!

(PS, resistant measurements did also fall outside spec with my motor. but spark gap was like 14mm. and removing the spark plugs and making a slow-motion video showed the correct firing order of the spark plugs.)

[ArjanStam]

additionally to my reaction above,

My CDI is looking exactly the same, with the white stuff on the back side and it's working fine after all...
if you can get it to run with the wiper arm disconnected. do you notice a change in RPM when you change the position of the wiper arm?

if yes, the CDI is doing its thing .

and note, after 20 seconds, the CDI will change the timing to lower RPM

[boscoe99]

According to a CDI professional, this is a sign of moisture entering through the advance/retard lever.

I don't agree. I have seen many perfectly good CDI's/ECU's with what looks like large grains of stuff in them.

[99yam40]

I don't agree. I have seen many perfectly good CDI's/ECU's with what looks like large grains of stuff in them.

even some new ones have that showing in the sealing fill.
some may just want to sell parts.
but you need to check to make sure the CDI is doing what it should be doing.
if it is not working properly then replace it

[avonsearider]

DAV adaptor ordered.

[avonsearider]

I am just waiting for a DVA adaptor to arrive.