Compression test needed - help

[dfrase]

Hey Guys,

Selling my boat and seller has requested a compression test on the Yammi 4 stroke 115. shops are booking way out.
Any advice on a local mechanic who would be able to do this in the near future? i am willing to pay more to get it done right away.

thx,
dfrase

 

[Pineapple Express]

I don't have the answer to your question, but stating your location will be helpful to others who may have suggestions

 

[ExFlyGuy]

Why not just do it yourself with the seller present?

It's not that hard and you can buy a compression tester at Canadian tire for under $50.

 

[dfrase]

I don't have the answer to your question, but stating your location will be helpful to others who may have suggestions

geez what an idiot!! yes, i am in victoria in Oak Bay

 

[Foxsea]

Why not just do it yourself with the seller present?

It's not that hard and you can buy a compression tester at Canadian tire for under $50.

Yes, a very simple job. Warm up the engine a little, just to get the oil circulating. Pull all the plugs - Yamahas have places to put them - wires on and grounded. Use the kill switch. Push the end of the tester into the plug hole and have your friend crank the engine for 4 or 5 revolutions. Read and record the pressure and repeat for each cylinder.

 

[profisher]

Fox you forgot throttle in wide open position when doing the test.

 

[Ground Tackle]

Try Deans Marine in Duncan

 

[Foxsea]

Yes, a very simple job. Warm up the engine a little, just to get the oil circulating. Pull all the plugs - Yamahas have places to put them - wires on and grounded. Push the end of the tester into the plug hole and have your friend crank the engine for 4 or 5 revolutions. Read the pressure and repeat for each cylinder.

Fox you forgot throttle in wide open position when doing the test.

Absolutely right! Yamaha says: Always use full throttle with ignition disabled when testing compression. This lets as much air as possible enter the cylinder so the cylinder condition, not the throttle restriction, may be tested. This is especially important when testing the compression on a high performance 4-stroke engine. Testing the compression with a closed throttle may produce readings as much as 80psi lower than normal.
Keep in mind, what you are looking for is close compression numbers for all cylinders (+- 10% is good) moreso than the absolute numbers.

 

[dfrase]

thanks guys!! turns out the buyer was engine savvy and had the compression tester. we figured it out and readings were great, all within 5% of each other. sold

appreciate the help,
dfrase