You're welcome. There is a small (and sometimes hard to read) stamped letter on the ID plate. This letter will tell the exact year your motor was built. However, there is a USA and a European date code chart. These two will tell you two different years for the same letter. If you send me this letter and tell me on which continent you are, I will tell you the year your motor was built.

​@@VintageOutboardMan Thank you for the video. I have a yamaha 4hp, built in Japan, and the serial number is S 210939. I live in France. Can you give me the year of my motor ? Thanks

@@stevenhubner634 The letter should be stamped in the black part of the ID tag, NOT in the silver boxes. I think the S you mentioned is the wrong letter and stands for 'short shaft'. If you provide me the letter stamped in the bottom left or bottom right of the tag, I can tell you in which year it was built.

@UC5gLpebSEdKyDGj94Qek_pQ The S is stamped on the left on the ID Tag (before the serial number).

@@VintageOutboardMan The S is stamped on the left on the ID Tag (before the serial number).

Hi, is the S part of the number before it, or is the S located separately in the right lower corner of the model tag? It should be a small stamped letter, not a painted one. And is your motor a blue or a grey one?

The S is in the bottom right hand corner of the model tag. The engine cover is grey, but may have faded in the Lake District sun. The upper/lower casings and transom clamp are medium grey colour. @@VintageOutboardMan

@bryanfitzgerald8046 Okay, yours is a 2001 model. I can only think of two things regarding the high idle speed. Either your throttle cable is way too tight, and the throttle won't rest on the idle stop screw (or the idle speed screw is screwed in way too far), or the idle mixture screw is set way too lean. Check the throttle adjustment first. If that checks out, start the motor and try to turn the mixture screw counterclockwise to richen the mixture and see if this lowers the rpm

@kody5779 Hi there. Not that I know, unfortunately. The 5hp gets its power advantage mainly from its bigger engine displacement. You could of course experiment with different propeller pitches and see what works best. Thanks for watching.

So the 5 HP does have bigger cylinders or something does it? I know with the smaller 2.5 mercury you can put out restrictor after the carb to easily make it essentially 3.3 HP I thought that was possibly the case with these 4 and 5 HP engines you have

I must have missed where you said they were different engine displacements, my bad

Where are you located? The date code means different years for different continents.

@@VintageOutboardMan I'm from Ireland but the guy I bought it from was from the UK

@@GameCastCubed If it's a blue one, it's from 1981, if it's grey it's from 2002.

@@VintageOutboardMan 1981 so I bought it for 150 euro running such a nice little engine. I also bought a 8hp for 300 which wasn't pumping I just took the lower unit off and connected a garden hose to clear the blockage and put a new thermostat in it and away she went.

Yes these are very nice and dependable motors. The American motors run nicer imho, but Yamaha can surely build engines!

@kody5779 It does make a difference, but if your boat isn't too big, 4hp will do the job. It will al depend on your usage and boat.

@@VintageOutboardMan would it be possible to fit 5hp powerhead onto the 4hp leg? Same bolt patterns?

@kody5779 I believe so, yes, but I'm not 100% sure.