Yamaha 4 stroke 25 hp

[rick_l]

I am having trouble with obtaining information on a Yamaha 25 hp 4 stroke. It is a 2000 year motor and the Model number is F25ELRY The quetions are:

1. What is the size of the rod journels? I am having the crank rebuilt and need to know the spec size?

2. Why does Yamaha have three different sizes of rod bearings and crank bearings?


I posted these questions earlier but have not received any answers. I counting on you guys.... thanks

 

[BruceAML]

Re: Yamaha 4 stroke 25 hp

Why don't you contact Yamaha customer service at (866) 894-1626. They are always helpful. In addition to the model number they will want the serial number. They open at 8:30 AM EST. In addition to the three sizes of bearings there are two sizes of pistons. One is standard and the other is .50 mm over size

 

[rick_l]

Re: Yamaha 4 stroke 25 hp

I have contacted Yamaha Customer service and they can not answer the questions. I have also contacted three Marina's who have Yamaha Master Tech's and they can't answer the questions. There only response is that Yamaha does not recommend rebuiding the crank. A new crank for this motor is around $#550. to $600. I can have the crank rebuilt for $150.00 and they say they can put it into specs if I get the rod bearing journels specs.

 

[rodbolt]

Re: Yamaha 4 stroke 25 hp

yamaha doesnt give us much as a spec as they dont offer oversize bearings like the automotive world.
I can give you the specs from a march 97 manual,
crankshaft outside diameter 42.884-43.000mm (1.692"-1.693")
main journal clearence is .012-.o44mm (.0005"-.0017")
crankcase marks-bearing color. A:Blue,B:BlackC:Brown.
crankshaft big end side clearence.05-.022(.0008-.002")
runout limit is .03mm(.0012")
but as Yamaha does not reccomend nor offers rebuilt cranks best your machine shop can do is measure a non damaged journal and try that.
its either that or measure all the bearing shell thickness and do the math.

 

[rick_l]

Re: Yamaha 4 stroke 25 hp

Thanks rodbolt, I think that is our best way to go. I am ordering new rods and bearings. They say they can measure the opening and then add the recommended oil clearence to it.

 

[BruceAML]

Re: Yamaha 4 stroke 25 hp

The reason for 3 different sizes of bearings is so that crankshafts are not turned into scrap at the manufacturing plant. Any slight variations are made up by the bearing size. The crank is color coded to the size bearing that is required. Yes, the crankshaft is rather expensive for a 2 cylinder engine.