Boat

Have Boat Questions? Ask a Boat Repair Expert.

Ask an Expert,
Get an Answer ASAP!

This answer was rated:

Are 90's acceptable compression for a 2005 Yamaha 4 stroke…

Second opinion] Are 90's...

Second opinion] Are 90's acceptable compression for a 2005 Yamaha 4 stroke engine

Mechanic's Assistant: Sometimes things that you think will be really complicated end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so the Marine Mechanic can help you best.

Looking at a boat with a 2005 Yamaha engine with approx. 400 hours

Mechanic's Assistant: Sometimes boat issues seem like they'll be really complicated, but end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Is there anything else the Marine Mechanic should be aware of?

The engine compression is in the 90s for all four cylindars of a 2005 Yamaha 4 stroke engine, it that acceptable?

Show More
Show Less
Ask Your Own Boat Question
Answered in 11 hours by:
6/27/2018
Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 18,217
Experience: Degree in Marine Technology. Gas and diesel marine mechanic.
Verified

Good morning, my name is ***** ***** am I speaking with? I read what you wrote. Do you have a model number on this engine, or even just a horsepower?

Ask Your Own Boat Question
Customer reply replied 1 month ago
90 HP with approx. 400 hours

Got it. Are you positive that this is a 4 stroke and not a 2 stroke engine?

Ask Your Own Boat Question

Got it. To answer your question directly, no, the compression numbers are no good. These are high compression engines. When the engine was new, it would have had compression readings of 200 to 220 PSI. As the engine wears and tears that number will come down. The lower limit is 124 PSI. Anything 124 PSI or lower Yamaha considers a fail, and the engine is either worn out or damaged. Click this link for a picture, this comes from the factory service manual - https://imgur.com/a/LS4AiV7 To be honest, if this engine actually runs, really what I would be the issue here is, is that the person doing the test use a cheap inaccurate gauge. I've seen harbor freight brand gauge and other cheap ones just like it be off by more than 50 to 60 PSI when compared to a high end compression gauge like a Snap On or OTC brand. Realistically speaking if this engine really did haver just 90 PSI it either wouldn't run or it would run terrible, and smoke like crazy. If it actually runs well, I would bet that the engine compression is actually much much higher than 90, and the real problem is a cheap gauge giving an innacurate reading. This engines compression should be double checked with a better compression gauge. Does that all make sense to you. I think that should do it but I work for tips so I do want to make sure you are happy with my service before you go. If you had a further or more specific question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. The ratings box is located at the top of the screen. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.

Questions do not close out, so if you have to come back later on with follow up questions to the issue you still can even after doing a rating.

Thank you
Jason

Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 18,217
Experience: Degree in Marine Technology. Gas and diesel marine mechanic.
Verified
Jason and 87 other Boat Specialists are ready to help you
Ask your own question now
Was this answer helpful?

How JustAnswer works

step-image
Describe your issueThe assistant will guide you
step-image
Chat 1:1 with a marine mechanicLicensed Experts are available 24/7
step-image
100% satisfaction guaranteeGet all the answers you need
Ask Jason Your Own Question
Jason
Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 18,217
18,217 Satisfied Customers
Experience: Degree in Marine Technology. Gas and diesel marine mechanic.

Jason is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!!

AlexLos Angeles, CA

Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, NC

Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around.

EstherWoodstock, NY

Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know.

RobinElkton, Maryland

He answered my question promptly and gave me accurate, detailed information. If all of your experts are half as good, you have a great thing going here.

DianeDallas, TX

< Previous | Next >

Meet the Experts:

Dominick

Dominick

Marine Mechanic

1,009 satisfied customers

25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified

Ted G.

Ted G.

Rigger, Diagnostician

704 satisfied customers

40 years boating, Safe boating instruct., Offshore Race promoter, Failure Analysis, Expert Witness

John White

John White

Marine Mechanic

306 satisfied customers

11 years experience working on outboards, inboards, sterndrives & pwcs

Jason

Jason

Marine Mechanic

18,217 satisfied customers

Degree in Marine Technology. Gas and diesel marine mechanic.

Tan

Tan

MerCruiser Certified Technician

11,264 satisfied customers

40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.

Jeff G.

Jeff G.

Marine Mechanic

4,729 satisfied customers

42 years experience, Certified Master Technician, All Major Outboards, Sterndrives, Hi-Performance

Captain Dave

Captain Dave

Marine Mechanic

2,672 satisfied customers

USCG Licensed Captain, 20+ Years Boating, Fishing, Maintenance and Repair Experience

< Previous | Next >

Related Boat Questions
Are 90's acceptable compression for a 2005 Yamaha 4 stroke
Are 90's acceptable compression for a 2005 Yamaha 4 stroke engine … read more
Clamp-onTech
Clamp-onTech
405 satisfied customers
I am thinking about buying a 2005 boat with a 2005 yamaha
Hi Jason, I am thinking about buying a 2005 boat with a 2005 yamaha vmax hpdi 250. Would you take a chance on the this motor or go with a four stroke.… read more
Jason
Jason
Marine Mechanic
Vocational, Technical or Trade Scho
18,217 satisfied customers
I'm looking to buy a 2005 yamaha 200hp four stroke. During
I'm looking to buy a 2005 yamaha 200hp four stroke. During the engine survey performed by a certified yamaha mechanic, the compression results were as followed. Compression test results cyl 1-165. cyl… read more
Clamp-onTech
Clamp-onTech
405 satisfied customers
2011 yamaha 90 hp 4 stroke (F90TXR) is losing oil. I recently
2011 yamaha 90 hp 4 stroke (F90TXR) is losing oil. I recently changed the oil and the boat was used for less than 10 hours and it is already low. There is no signs of oil leaking from the power head b… read more
Jeff G.
Jeff G.
Marine Mechanic
Vocational, Technical or Trade Scho
4,729 satisfied customers
i want to repower 1995 Pursuit 2470 CC It presently has twin
i want to repower 1995 Pursuit 2470 CC It presently has twin yamaha 150hp saltwater series engines. any Advice?… read more
Clamp-onTech
Clamp-onTech
405 satisfied customers
Curious about how to decide how much weight the outboard motor
Curious about how to decide how much weight the outboard motor can safely weigh? I have a 1996 aluminum Lund Tyee model 1650. Lund says the max rated HP is 115. I. Want to replace the 90 HP mercury 2 … read more
Jason
Jason
Marine Mechanic
Vocational, Technical or Trade Scho
18,217 satisfied customers
Approximately what is the cost for parts and labor to replace
Approximately what is the cost for parts and labor to replace a power head on a yamaha 4 stroke engine and or the gear box? I am trying to decide if I should buy a boat with 2003 Yamaha 4 strokes with… read more
Jason Forsberg
Jason Forsberg
Outboard Marine Mechanic
Vocational, Technical or Trade Scho
531 satisfied customers
i have a 1997 bayliner trophy 2002 whit a 125 hp force outboard
i have a 1997 bayliner trophy 2002 whit a 125 hp force outboard . i would like change mi outboard for a new one . whitch one and how hp tanks.… read more
Jason
Jason
Marine Mechanic
Vocational, Technical or Trade Scho
18,217 satisfied customers
I have a 2001 22ft Key West w/1993 v6-200HP Yamaha w/25 shaft.
I have a 2001 22ft Key West w/1993 v6-200HP Yamaha w/25" shaft. Compression is 90-110. I was thinking of purchasing a used outboard, refurbished used outboard or a complete rebuilt Yamaha. What is the… read more
Jason
Jason
Marine Mechanic
Vocational, Technical or Trade Scho
18,217 satisfied customers
We are looking at a power boat with a 10 year old 115 Yamaha
We are looking at a power boat with a 10 year old 115 Yamaha motor. The compression check reads 115, 120, 110, 115. Of course there are no guarantees, but what is your opinion about this motor? Will i… read more
Jason
Jason
Marine Mechanic
Vocational, Technical or Trade Scho
18,217 satisfied customers
Hi, I have just fitted two 115 4 stroke Mercs(2010) to a 7.2mtr
Hi, I have just fitted two 115 4 stroke Merc's(2010) to a 7.2mtr Fibre Glass boat. The boat originally was fitted with twin 100 yamaha four strokes. I spend most my time trolling at around 6 - 10 knot… read more
Jeremy R
Jeremy R
1,069 satisfied customers
I have 1984 Evinrude outboard motor on my 1984, 17 ft. Boston
I have 1984 Evinrude outboard motor on my 1984, 17 ft. Boston Whaler boat. The engine began to have problems at the end of summer. It would shut off at about 1/2 throttle. The boat mechanic performed … read more
Captain Dave
Captain Dave
Marine Mechanic
Master's Degree
2,672 satisfied customers
i am looking at a 2001 grady white marlin. This boat has twin
i am looking at a 2001 grady white marlin. This boat has twin yamaha V250s with about 300 hours. my questions, are these 4 strokes, are they any good compared to the new yamaha 4 strokes, and to chang… read more
Jeff G.
Jeff G.
Marine Mechanic
Vocational, Technical or Trade Scho
4,729 satisfied customers
Looking at a used 2001 29 Pro sport cat has twin 2001 200 HP
Looking at a used 2001 29 Pro sport cat has twin 2001 200 HP Yamaha HPDI outboards on it. I know the newer 200 HP Yamaha HPDI outboards are pretty good reliable motors but I was wondering if the older… read more
Jason Forsberg
Jason Forsberg
Outboard Marine Mechanic
Vocational, Technical or Trade Scho
531 satisfied customers
I am looking to buy a used MirroCraft boat w/2005 90hp 2-stroke
I am looking to buy a used MirroCraft boat w/2005 90hp 2-stroke mercury motor Has there been any problems with that motor I should know about? Anything i should ask the dealership about the motor?… read more
Dominick
Dominick
Marine Mechanic
Vocational, Technical or Trade Scho
1,009 satisfied customers
I want to repower my 1988 Searay Laguna. It is powered by 2
I want to repower my 1988 Searay Laguna. It is powered by 2 135 Mercuty motors. Should i stay with Mercury or or go with Honda, Suzuki or Yamaha?. Which one will give me best or least fuel consuption?… read more
Dominick
Dominick
Marine Mechanic
Vocational, Technical or Trade Scho
1,009 satisfied customers
I have an 06 Yamaha 40 four stroke used on a Carolina
I have an '06 Yamaha 40 four stroke used on a Carolina Skiff bought new. The engine has approx. 25 hours and recently developed a problem in the mid-range speed. It starts well and runs well at an idl… read more
Pappy&#039;s Sales and Service
Pappy's Sales and Service
Vocational, Technical or Trade Scho
586 satisfied customers
Hi. I have a 2005 Yamaha 70hp outboard motor. I noticed ...
Hi. I have a 2005 Yamaha 70hp outboard motor. I noticed that the 90hp model hs the same bore and stroke, and I think the same compression as the 70. Is there some way to increase the power of the 70 t… read more
Pappy&#039;s Sales and Service
Pappy's Sales and Service
Vocational, Technical or Trade Scho
586 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x