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No Idle 9K Max RPM

buckbuck

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Location
Texas
Boat Make
Yamaha
Year
2008
Boat Model
X
Boat Length
21
@rsjohnsn I went back through a half dozen YDS reports on my 2008. I saw timing numbers vary between 5 and 15 degrees BTDC. Are you sure you have a timing issue?
 

rsjohnsn

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The only thing I know is that the engine that runs good is at 5* BTDC at idle and it doesn't move. The engine that I am having issues with is at 15* BTDC and it fluctuates. I have moved every sensor, coil, plugs and ecm from the good engine and nothing has changed. I don't really know where to go from here. I'm going to pull the valve cover and at least verify timing is correct. I am open to any and all suggestions. Thanks
 

wajetter

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AR
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If so, can I do this without pulling the motor?
Yes, can be done. There's a youtube video of a guy doing it on MR1. Roughly this:
1. Put engine on top dead center (compression stroke) (this tool can be used) https://www.amazon.com/dp/B08W235VJW
2. Remove chain tension with a screwdriver (clockwise)
3. Remove camshafs
4. Double check cyl 1 is still precisely on TDC
5. Put the camshafts on their marks. Be sure there is already a chain tension between camshafts, so when the chain tensioners are applied back, the camshaft degrees will not be spread out. If the chain has some slack, the chain tensioners will spread the camshafts when applied.
6. Torque the camshaft brackets.
7. Spin by hand to ensure no valve intereference.
8. Crank without sparkplugs and check each cylinder compression.
 

wajetter

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What compression did you measure on this engine? Measure hot and with THROTTLE OPEN. It matters, as that is a true test per manual.
 

rsjohnsn

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I can't do a compression test at the moment as it is apart. The original compression test was 140 and 145 on a cold engine?
 
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