replace all Yamaha carbs Chapter 2

[colayn]

Re: replace all Yamaha carbs Chapter 2

It is twisted pair, 14 conductors, shielded wire bundled in a cable.
No cable number on it, but looking up the manufacturer website, the worst case is 150v rating , tested at 1000 vAC for 1 min

I do plan to run on the hose at 1500 before taking off to the lake.

I do have the info needed to check the charge coils. First time they have came up, so I didn't know they were suspect. For my education, brief explanation of their function.
Will plan to test.



Per the questions in previous post, are all test DC ?
And outside of the CDI output, do the others test to grd or to the wire mated to it per the manual ?

 

[99yam40]

Re: replace all Yamaha carbs Chapter 2

I would follow the manual as to where to put the meter leads and as far as I know the meter is set to DC on all those tests, but make sure that is what the manual says. Usually the manual will tell you what to test first and if that is low or OK then replace or test the next component.
I tend to follow it step by step, that is why I said something about the charge coils

 

[boobie]

Re: replace all Yamaha carbs Chapter 2

Instead of buying that expensive test wheel you can find a beat up alum prop that will fit your motor, get a sawsall and start clipping the blades off equally then running it. When you find a happy spot 4500-5000 rpm leave it there. You now have a test wheel for a reference point. Mercury Outboard did this years ago before they had test wheels when OMC did.

 

[99yam40]

Re: replace all Yamaha carbs Chapter 2

If you do that on a known good motor then you might be able to do it properly but I doubt it, You are looking for load(torque) with no or little forward thrust not just some RPM but if you are working on a motor that maybe sick you have no reference unless the prop was tested on a good motor and the results are known.

 

[Don S]

Re: replace all Yamaha carbs Chapter 2

Hey Bubba, let's cut some more off them prop blades, we ain't gettin' 'nuff rpmz.

 

[rodbolt]

Re: replace all Yamaha carbs Chapter 2

sumun hol muh beeer?

 

[99yam40]

Re: replace all Yamaha carbs Chapter 2

I do have the info needed to check the charge coils. First time they have came up, so I didn't know they were suspect. For my education, brief explanation of their function.
Will plan to test.

low speed charge coils provide the voltage to the CDI capacitors for firing the coils at low RPM and the high speed charge coils provide it at the higher RPM would be my thoughts

 

[99yam40]

Re: replace all Yamaha carbs Chapter 2

sumun hol muh beeer?

I never ask for "sumun to hol muh beeer" cause I know I will never get it back from those guys even if I could try to finish it off after the show

 

[colayn]

Re: replace all Yamaha carbs Chapter 2

Did a test run on my wiring today before going to the lake.
I either found a problem or doing something wrong. See charge coil data, attachment.
Also tested compression once again to be sure.
See attached sheet with the data.
1- I did find the shop put B7HS-10 plugs in instead of the resistor type BR7HS-10. will that cause any interference in the elec. circuit ?

As you can see almost all my readings are higher than the manual spec.
I am thinking it is because of running with no load ???? Correct ???

Used the DVA and a Fluke 189 for all measurements.

The Hi and Lo charge coil readings are way off at 1500 RPM
I checked and double checked continuity.
I tried with out DVA using AC and DC setting both (my manual doesn't specify) but readings were still way off. low.

 

[rodbolt]

Re: replace all Yamaha carbs Chapter 2

numbers look ok for running on a flusher.
remember, for electrical tests when they say loaded or unloaded it simply means is the device plugged in or not.
also remember the voltages are minimum specifications.
but the CDI output needs to be checked at the problem RPM and engine load.
yes non resistor plugs can do funny things,yes bad plug caps can do funny things.

 

[colayn]

Re: replace all Yamaha carbs Chapter 2

OK, I will get the resister plugs. Just noticed that one doing compression.
I thought the voltages were OK do to know load, just concerned about the Charge coil high and low, both were WAY off spec.

Am I correct in using the DVA for all checks ? With it all were close except the charge coils

Sorry, just realized the charge coil data was not on the attachment.
High coil 2.6v idle - 2.0v R1500
Low coil 233v idle - 210v R1500

Next test WOT at the lake when I can go.

 

[rodbolt]

Re: replace all Yamaha carbs Chapter 2

high speed charge coil voltage is way off, you either did the test wrong or you have a stator issue.
remember, the spec is MINIMUM.
220 isnt bad for low speed charge coil output.
no sense in lake testing until you find out why the high speed charge coil voltage is so low.
check each high speed charge coil lead for shorts to ground and the resistence between both leads.

 

[colayn]

Re: replace all Yamaha carbs Chapter 2

I will check as requested.
I tested it the same way as the low side, just using the other conductors. (blue - black/red)

For my education, IF the High coil is not working properly would that mean
the proper charges aren't generated at high RPM resulting in poor high end performance

 

[rodbolt]

Re: replace all Yamaha carbs Chapter 2

egggzacary.

 

[colayn]

Re: replace all Yamaha carbs Chapter 2

I'm getting excited now !!
Try to get back on it tomorrow if work doesn't go to late.

 

[99yam40]

Re: replace all Yamaha carbs Chapter 2

This stuff is easier than you thought aint it,
Just need the manual and proper test equipment

 

[colayn]

Re: replace all Yamaha carbs Chapter 2

yes and no. With you guys walking me thru it is pretty easy. I just have to struggle thru the terminology.
My Yamaha manual has been great for illustrations to help ID parts and with and general specs. But it assumes you already know a lot.
I have another set of manuals on CD, with are far more detailed, but with 1750 pages trying to sift thru the pdf file on a PC it is real hard to find what you need.
I have spent countless hours working on the problem, studying , testing ,etc but it has been a good experience. That engine doesn't intimidate me any more.

Going to get back on that charge coil today I hope after work. I have checked and rechecked my connections and continity (slide small wire in the back of the connector, soldered on my test leads and taped)
Hopefully I can update tonight with root cause.
Thanks fellows for the help, I truly appreciate it.

PS, on another note, I also found the adjustment screws on the actuator for the timing don't have jam nuts. Doesn't seem right to me. Wonder if someone removed them and that is all out of whack. I will get into the book and check out the procedure to see if it is close to were it suppose to b.

 

[rodbolt]

Re: replace all Yamaha carbs Chapter 2

the stopper on the magneto control lever is for idle timing, the stopper on the intake that the control lever hits at WOT is for WOT.
about the only way to check it is at WOT full engine load.
that is where either the IDC dyno or YB1626 is so handy.
and yes, they originally had jam nuts and a tamper proof coating on the threads.
remember, the charge coils, like the pulsers are TWO wire coils.
open a wire or winding and you lose both the positive and negative portions of the A/C sine wave.
short one wire to ground and you lose about 1/2 the voltage and one entie portion of the sine wave.
think of the charge and pulser coils as simple A/C alternators that feed a device.
cause thats about all they are.

 

[colayn]

Re: replace all Yamaha carbs Chapter 2

even though a sine wave is generated I still use the meter set on DC with the DVA to measure ??
Correct ?
The manual doesn't specify AC, DC or when DVA is required.
Above is the only way I could get much of any reading

 

[rodbolt]

Re: replace all Yamaha carbs Chapter 2

set the meter to Vdc.
what your looking for is a voltage peak.
most meters read voltage average thats why the DVA adapter is nessasary.