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Monsoon 350 Compression


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2013 VLX with Monsoon 350, 747hrs. Dealer did compression test. Cold 1: 145,  2: 120,  3: 145,  4: 120,  5: 115,  6: 130,  7: 130,  8: 130.   Warm 1: 160,  2: 150,  3: 145,  4: 120,  5: 115,  6: 130,  7: 130,  8: 130.  Says that cold is 20% differential and warm is 21% differential with this it results in compression failure as lowest should read within 10% of highest. Engine Failed compression test.

Does this seem like a failed comression test?  They are telling me it needs to be rebuilt or replaced.

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From the Indmar procedure. 

Compression Test Procedure 
1.Charge the battery if the battery is not fully charged. 
2. Disable the ignition system. 
3. Disable the fuel injection system. 
4. Remove all the spark plugs. 
5. Block the throttle plate wide open. 
6. Start with the compression gauge at zero, and crank the engine through four compression strokes 
(four puffs). 
7. Make the compression check for each cylinder. Record the reading. 
8. If a cylinder has low compression, inject approximately 15 ml (one tablespoon) of engine oil into 
the combustion chamber through the spark plug hole. 
Recheck the compression and record the reading. 
9. The minimum compression in any one cylinder should not be less than 70 percent of the highest 
cylinder. No cylinder should read less than 690 kPa (100 psi). For example, if the highest pressure in 
any one cylinder is 1035 kPa (150 psi), the lowest allowable pressure for any other cylinder would 
be 725 kPa (105 psi). (I035 x 70% = 725) (150 x 70% = 105).

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40 minutes ago, FlyinThrush said:

2013 VLX with Monsoon 350, 747hrs. Dealer did compression test. Cold 1: 145,  2: 120,  3: 145,  4: 120,  5: 115,  6: 130,  7: 130,  8: 130.   Warm 1: 160,  2: 150,  3: 145,  4: 120,  5: 115,  6: 130,  7: 130,  8: 130.  Says that cold is 20% differential and warm is 21% differential with this it results in compression failure as lowest should read within 10% of highest. Engine Failed compression test.

Does this seem like a failed comression test?  They are telling me it needs to be rebuilt or replaced.

Does the engine otherwise run OK, or did they test the compression for some reason?

Just doing a compression test and declaring that it needs a rebuild seems just a touch sketchy to me.  For example, they could do a leakdown test to see if it is rings or valves.

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Was getting a backfire happening.  Seemed to be running fine otherwise. Did it in the process of checking everything out.

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