redstarweb
Recruit
- Joined
- Jun 25, 2006
- Messages
- 1
Hello Forum,
First I have tried to find answers on existing topics, but I think my problem is pretty unique.
I have polyester console boat, 4.20m 190KG (empty weight). I have a 40HP Yamaha 1994 2-stroke long-tail outboard.
First when I tried my new boat, I had a RPM cutoff at about 5800rpm. (this Yamaha has a rpm range between 4500 and 5500) My boat load at that time was 2 adults and 2 childs.
I advised my dealer and he advised me to use a maxmium propellor pitch (which is 15") to lower down the max. rpm, because this engine is a little overpowered for my boat.
So I fixed the new 15" propellor and today I had a boat ride with 4 adults and 2 childs. Around 4100rpm the boat was coming in plain (with this load) while having a speed of about 4500 rpm, after 20 seconds the rpm died again.
Although my rpm range is between 4500-5500, why dies the engine at 4200/4300 rpm?
I also have to tell you that when I cutoff the throttle at that moment, a lot of smoke (unburned fuel?) is coming from the exhaust.
Is it beacuse of the load (4 adults-2childs) or is it possible that something else is wrong (like a fuel starvation)?
I really hope some of you can give me some advise.
Thanks!
Bart Dirks
The Netherlands
First I have tried to find answers on existing topics, but I think my problem is pretty unique.
I have polyester console boat, 4.20m 190KG (empty weight). I have a 40HP Yamaha 1994 2-stroke long-tail outboard.
First when I tried my new boat, I had a RPM cutoff at about 5800rpm. (this Yamaha has a rpm range between 4500 and 5500) My boat load at that time was 2 adults and 2 childs.
I advised my dealer and he advised me to use a maxmium propellor pitch (which is 15") to lower down the max. rpm, because this engine is a little overpowered for my boat.
So I fixed the new 15" propellor and today I had a boat ride with 4 adults and 2 childs. Around 4100rpm the boat was coming in plain (with this load) while having a speed of about 4500 rpm, after 20 seconds the rpm died again.
Although my rpm range is between 4500-5500, why dies the engine at 4200/4300 rpm?
I also have to tell you that when I cutoff the throttle at that moment, a lot of smoke (unburned fuel?) is coming from the exhaust.
Is it beacuse of the load (4 adults-2childs) or is it possible that something else is wrong (like a fuel starvation)?
I really hope some of you can give me some advise.
Thanks!
Bart Dirks
The Netherlands