Yamaha 4HP Std Shaft Length

Chris · 05 April 2007, 09:16

Does anyone kow what the measurement would be for this engine for the length of the shaft?

Chris

Nos4r2 · 05 April 2007, 09:29

Hard to say-some people describe standard as Standard Longshaft, others say Standard shortshaft. Got a pic? It'll be either 18" or 21".

As long as the prop is in clear water ie below the transom at the point where the shaft passes it then it won't be a problem using either.

Downhilldai · 05 April 2007, 21:14

Low powered standard shaft engines tend to be 17"-18" from the underside of the saddle to the cavitation plate. Longshaft will be an additional 5".

Downhilldai · 05 April 2007, 21:16

If you're looking at a 4hp 4-stroke Yam, then it's easy to distingish between standard and longshaft, as the longshaft has a 5" spacer between the mid section and the gearbox.

Chris · 06 April 2007, 08:22

I took a measurement of the transom at the poin the engine would be mounted and it measures about 19" from top to bottom, so I guess that would indicate a Std shaft would be fine or would I be better off with a long shaft and have the prop lower down?

Chris

Nos4r2 · 06 April 2007, 10:48

That's a hard one. Best bet is to put it on the transom and see.
You might not get away with a short shaft. The prop needs to be in clear water-That or it needs to be far enough away from the transom that you don't get cavitation problems at high revs from lack of water flow.
At a guess with a small outboard that'd require an auxiliary bracket though you might get away with setting the trim pin out a hole.

If you get a long shaft it's going to work without all the fuss.

jyasaki · 06 April 2007, 16:26

Yamaha lists their 4hp 4-stroke shaft lengths as 15" or 20" (that was the only 4hp motor I saw.)

I'm thinking you probably should go long.

jky

fast fred · 09 April 2007, 14:14

Standard = 15", long =20", and so on