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25 2-Stroke Timing Question (Incorrect Flywheel Degree Indication?)

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Yanibm1

New member
Short Summary:

  • SELOC manual instructs to position the piston at .13" BTDC and to adjust the link joint length so that the timing indicator aligns with the marking on the flywheel. The specifications also list the full advanced timing as ~25, or 24-26.
  • Finding TDC with a dial indicator, the hash mark on the flywheel indicating TDC aligns perfectly with the reference arrow; however, when timing is adjusted properly using a dial indicator @ .13" BTDC on my motor, the flywheel indicates the timing is at 22 degrees, not around the 25 degree mark.
  • When adjusting idle speed, the manual instructs the user to set the timing at 7 degrees ATDC, using the hash marks on the flywheel.

Question:

I presume the dial indicator method is the most accurate way of setting the timing and therefore is why the method is recommended instead of using the hash marks on the flywheel; however, the idle speed timing is supposed to be set using the marks on the flywheel instead of finding some determined piston position with a dial indicator. Since the dial indicator method has shown the degree marks on the flywheel are not an accurate indication, I presume they are also inaccurate for establishing proper idle timing.

Does anyone have any suggestion on how to determine a proper idle setting using the dial indicator or other method? Not sure how I would calculate the piston position.

Am I missing something or doing something wrong?

I appreciate the help!

edit: Motor is a 2003 25MSHB
 
Last edited:
ClassicAQ said:
Setting the ignition timing is pretty straightforward. No need to calculate position of piston since the markers on the wheel indicate TDC/BTDC.

Here is a link for the service manual for your engine. Page 3-2. Follow the instructions.

https://www.vansoutboardparts.com/s...hop-manuals/382-2003-yamaha-20v-25v-25v2/file
Click to expand...

Thanks for that resource; however my motor, the 25M, isn't listed. I assume they are practically the same? Do you have a link for the 25M?

I am a bit OCD when it comes to these things and want to ensure I get it all set up correctly and more so understand why it is the way it is.
 
Actually yes, look at 3-3 – says to align the piston with a dial guage to .13" BTDC and then set it accordingly. But .13" BTDC does not align with 25 degrees as stated on 3-2, it aligns with 22 degrees.
 
Turns out I read the dial guage wrong by a few markings...:rolleyes:

But now the problem is that I can't get the link joint length screwed in enough to get to 25 degrees. It's close but not quite there.
 
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