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Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10964
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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We have a 200hp 2 stroke, 16 year old. It vibrates badly at

Customer Question

hi - we have a 200hp 2 stroke, 16 year old. It vibrates badly at 2600rev. Any suggestions please?
Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.

Hello. My name is Tan.

Check the prop shaft for wobble. Tilt the lower unit up put engine in neutral and spin the prop watch the prop shaft at the end. Does it wobble?

Is the prop banged up badly?

Customer: replied 1 year ago.
it does not wobble. Prop is new
Expert:  Tan replied 1 year ago.

Ok does the engine run up to full throttle wit no vibration?

If no vibration and it turns up to full throttle we will have to use a timing light to check for an ignition misfire at 2600 rpms.

Do you have a timing light?

Customer: replied 1 year ago.
goes up to full throttle ok - no vibration either side of 2600. We have checked the timing with a timing light
Expert:  Tan replied 1 year ago.

We won't be checking the timing we are checking the spark on each cylinder. What you do is connect the timing light to #1 cylinder run the boat up to 2600 rpms where the vibration is. Watch the flash of the timing light. You want a steady flash with no dead spots. If no misfire move to the next cylinder down. Run the boat check the flash of the light. Do this on all cylinders. If you find a misfire move that coil to a known good firing cylinder. Did the misfire move? If it moved then the coil is bad. If the misfire stayed then you have another ignition component failing. This will require a peak reading volt meter to do further testing.

Customer: replied 1 year ago.
hi Tan - the craft has changed hands (with our warranty) so we have to wait and see if the new owner wants to sort out the problem.
Expert:  Tan replied 1 year ago.

Ok Keep me posted. .........Please don't forget to positively rate my help as that is the only way I get credit for helping you.

Rate by clicking the stars at the top of the page 3 or more please.

Keep me posted...........Thank you........Tan

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