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NOTE: For figures and guidelines on compression service limits see specifications in your factory Repair Manual. Low compression pressure can indicate one or more of the following :

• Excessively worn cylinder wall
• Worn piston or piston rings
• Stuck piston rings
• Poor seating of valves
• Ruptured or otherwise damaged cylinder head gasket

Test procedure

1. Start and warm up the engine, then shut the engine off.
2. Remove the spark plug.
3. Install the compression gauge into the plug hole.

Compression gauge is a special tool required when performing a compression check on your Suzuki four stroke outboard motor.
Special tool required: Compression gauge adaptor

4. Disconnect the safety lanyard from the emergency stop switch.

WARNING: Disconnect the safety lanyard from the emergency stop switch prior to cranking the engine. This will prevent any residual fuel discharged from the cylinders from being ignited by a spark discharged from the spark plug cap.

5. Move and hold the throttle control grip in the full-open position.

6. While cranking the engine with the recoil starter, note the maximum compression pressure reading on the gauge.


Suzuki Models / Horsepower / Model Years

DF4 DF4 DF6 DF9.9 DF15 DF25 DF30 DF40 DF50 DF50 DF40QH DF50QH DF40T DF50T DF40Y DF50Y DF70 DF80 DF90 DF100 DF115 DF175 QH T Y 4HP 5HP 6HP 9.9HP 15HP 25HP 30HP 40HP 50HP 60HP 70HP 90HP 115HP 140HP 150HP 175HP 4 5 6 9.9 15 25 30 40 50 60 70 90 100 115 140 150 175 HP 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 99 00 01 02 03 04 05 06 07 08 09 10 11 Service Manual Repair Owner's Guide Diy Boat Engine Four Stroke 4-Stroke How To Fix.