What should compression be at for a ELPTO 90HP - 2005

PaulKim

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I know that the main concern should be for the difference between the clynders for compression. I just check mine and it is 101,102,101. As far as difference is concerned I don't seem to have an issue.<br /><br />But a range of 100 for compression seem really low, as my little 15HP has a compression of 120 and 119. <br /><br />Does anyone know what the compression should be on a new motor which has less than 10hours?<br /><br />Thanks
 

Rabbitdawghunter

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Re: What should compression be at for a ELPTO 90HP - 2005

Most people that I know use about 100 as a threshold . If it cranks and idles ok and everything seems to be ok otherwise I would leave well enough alone until it really breaks.
 

PaulKim

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Re: What should compression be at for a ELPTO 90HP - 2005

Thanks Rabbit for the reply.<br /><br />What I'm concerned about it that I still have about 1 month of warranty left on the motor and if 100 is a threshold, that doesn't seem right for a new motor. Does anyone know what the Mercury's spec is for minimal compression.<br /><br />Thanks
 

WillyBWright

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Re: What should compression be at for a ELPTO 90HP - 2005

No manufacturer has ever published such a spec. Why? Cuz your compression gauge may not be accurate. Few are. Put any two different gauges on the same motor and you'll get different readings. They give you a ballpark reading and that's all. They don't want to replace powerheads based on unreliable instruments. The only exception is that Yamaha started providing specs this year, but only as base guidelines. Ring/piston design provides higher compression when the motor is running. 100s is common from what I've experienced with those.
 

T_I_M

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Re: What should compression be at for a ELPTO 90HP - 2005

90 to 115 psi for those engines is just fine . The main thing is their within ( and here is big debate lies )15% of each other.Some say psi and not % and some say no more the 10 psi or %.
 

phatmanmike

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Re: What should compression be at for a ELPTO 90HP - 2005

sounds fine man. larger motors dont have as much psi as smaller ones. <br /><br />my 225v6 johnson only has 90psi and my 50hp 2 cylinder has 150 psi.<br /><br />go figure
 

PaulKim

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Re: What should compression be at for a ELPTO 90HP - 2005

Thanks for all of the replies, that will put my mind at ease.
 

MercFan

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Re: What should compression be at for a ELPTO 90HP - 2005

As your engine runs-in compression will increase aswell.
 

emckelvy

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Re: What should compression be at for a ELPTO 90HP - 2005

Some loopers don't develop big compression values for a comp test because of the porting, etc. The critical thing here is how it runs, and the fact that all three compression readings were virtually identical.<br /><br />Plus the issue pointed out that compression gages do vary, unless you have a just-calibrated gage you really have no way of knowing it's entirely accurate. But, as long as the compression gage has good repeatability, you know that if you're getting even readings she's a good one.<br /><br />I'd say don't worry, we should all have such good compression readings, within 1 psi of each other!!!!<br /><br />Cheers.........ed
 

Bigjohn1

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Re: What should compression be at for a ELPTO 90HP - 2005

Since you are looking for actual values, recommend you do yourself a favor and purchase the factory manual for your engine. These values are not industry secrets and are published via most factory and aftermarket repair manuals. I own a 2005 115efi 4-stroke and the published value for my cylinders is 135psi. This is listed in the engine specifications section right under the compression ratio. This is from the Merc official factory manual.
 

timmathis

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Re: What should compression be at for a ELPTO 90HP - 2005

Like they say all within 10% Don't worry be happy. Take care of it and it will last you a long time. Use plenty of good oil. Keep it serviced and it should take care of you...Tim
 

PaulKim

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Re: What should compression be at for a ELPTO 90HP - 2005

Thanks again, it will let me sleep better at night.
 
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