C40tlrx timing retarded below 12 ATDC

[99yam40]

I have adjusted the linkage as the manual said but when I checked the timing at idle with a timing light it reads ( 12-14 ATDC) way past the 7 degrees ATDC that the indicator shows on the CDI box. Full advanced still shows to be at the 25 BTDC degree mark with the light?
Is there a chart out there anywhere that gives the timing compared with the RPMs as they go up?
Is there a way to adjust just the low end without affecting the high end?

I have looked at some web sites for a CDI box just in case I need to buy one and for my motor the part number 63D 85540 00 00 has been replaced with 63D85540 01 00, which has been replaced with 63D85540 02 00 ,which has been replaced with 63D85540 03 00 ,which has been replaced with 63D85540 04 00. but not all part places say that the 63D85540 04 00 is for my 1999 C40tlrx.
Can anyone give me some incite to the changes over the years to the CDI boxes and how they may affect the older motors?
Or is it that I could use anyone of the part numbers if I can find one

[99yam40]

Just got back from running motor on the water. I had adjusted the retard stop screw to about 25mm instead of 20 mm just to get the timing to 10 ATDC instead of 14 ATDC and help with the idling. This still allowed for the TSP to move the timing a small amount before moving the butterflies
Checking the WOT timing with timing light showed about 28 BTDC, so I adjusted the advance stop screw to get it back to 25.
The motor still has some random RPM drops from time to time mostly 3/4 to WOT, but it is not due to timing change or fluctuations because I watched the timing while the RPMs were moving around and it stayed steady. I am only going by feel and sound, I do not have a tac.
I did notice that the RPM drops were not as bad when I removed the cowling and silencer from the front of the carbs and was running into the wind, was a little worse running with the wind. This sounds strange like it is running too rich or something with the little bit of restriction from the silencer. It did not help to adjust the mixture screws and it definatly killed each cylinder as I choked the individual carbs with my hand.

I have read most of the threads about timing, but I have not seen anything which states the retarded timing being this low with the pointer being on the 7 degree mark.
Even the treads about bogging and/ or surging do not give any definite answer to what finally fixed the problems.
I have been though the carbs, fuel pump, and fuel lines. The bulb stays firm and I have changed the plugs.

Any and all help would be appreciated.

[99yam40]

Help needed from anyone that has knowlage of what all affects timming on C40TLRX

I am trying to find out if the only thing that would affect the timing on my C40TLRX is the CDI unit. Can anyone give me some information, Please reply if you have had any experience or knowledge on the subject.

[99yam40]

I am trying to find out if the only thing that would affect the timing on my C40TLRX is the CDI unit. Can anyone give me some information, Please reply if you have had any experience or knowledge on the subject.

Is there anyone out there that is familiar with the timing changes that can occure to a motor controled by the CDI boxes?

[99yam40]

Just-In-Time can you give me any advice on this timing issue?

Can you tell me where to find info on how much the timing is retarded or advanced by the CDI unit on a Yamaha C40TLRX under certain conditions and what those conditions are.

It seems that the timing is advanced to about 4 degrees BTDC at start up and warm up and then drops back to what ever you have the retard stop screw adjusted to, but I do not know anything else like what will retard it and the conditions that will cause it and how much.

[99yam40]

Still looking for some kind of reply from someone with knowledge