Yamaha 3HP Malta

Honda Z50M said:
I don't see how the engine being a little deeper in the water would account for 40% power and te Malta apears to have an exhaust bypass to elleviate back pressure.

May be I am expecting too much from a little engine although 95% of the time throttle is at start position or less just pootling along the river.

Tom
Click to expand...
The back pressure does make a difference as to how the engine runs. The bypass is there only to help with starting and on my Malta is a couple of small holes only.
I had the same problem with my main engine, a Honda 30. Ideally I need to raise it up a bit more but then it would cavitate all the time. All a compromise.
 
Right sorry for delay in updating to day was the first trip on the river since last post.

I fitted a little rpm meter and under load with prop engaged on the river max rpm was 2100, idle (prop not engaged) was spot on at 1200.

Air mix screw now 1.75 turns out
 
Milgrip said:
Even in perfect condition a Yamaha 3HP Malta (6L5 would behave a little sluggish (pushing 3.2M dinghy with 2 adults and 2 children).
Try a larger engine.
Click to expand...

This.



The best you can hope for out of that combo is going to be about 4 knts and with a bit of prop slippage thrown in that is going to be about 2k rpm. What were you hoping for?
 
Hi I wasn't hoping for anything only that was sure if the rpm being so low at full throttle was normal (novice, first dinghy, first motor) although some of the changes/fixes I have done have seen improvements.

Our normal engine speed crusing the river is around or just under 1200rpm (with throttle around the start position)
 
On my 3.3hp tohatsu that is about the same. Any more and the bow rises, I create more wake and sure the revs will climb to about 3k but that is because of prop slippage and the fact the plastic prop is just deforming, more speed I dont get. With your setup at 3.2m 2 adults and 2 kids you'd be lucky to get on the plane with a 10 on, even a 15 may struggle. You may want to invest in a finer "high thrust" prop if one is available for your engine but that will make marginal difference to speed but give you a bit more throttle control
 
I also have a malta and on my 302 m Sibs about 4 knots is all you can get. I think you are expecting too much. If you can get about 4 knots I would say all is ok.
 
Actually used ours the other day for more then 5 minutes, I found more than half throttle is a waste of time, more noise with a very slight inscrease in speed.
 
Went out on the river last weekend with 2 adults and 4 kids and managed exactly 5mph (4.35knots) with engine speed at 2250rpm

So my conclusion is with thanks to all your input there's bugger all wrong with it! and it's running sweet as!

Thanks

Tom
 
You must log in or register to reply here.

Share this page

Top