New engine still no power

Dont mess with the injector pump!! there lies loads of beer tokens down the drain!
Id be looking at strange restrictions, some stack pipes in the tank have a small filter on the end, although I suspect something even stranger like a piece of debris in a pipe or a collapsed inner flexible pipe.
Bear in mind that I dont want to start a wild goose chase, am basing my conclusions on the info supplied.
Does the lift pump pump ok? take the outlet from it off and pump in to a jar to see if it puts out OK, then connect it and go to the next point and try again etc.

Sorry have just seen the other post you made. If you suspect the pump, get it seen to by an outfit that fixes them, dont get a "marine engineer" to fiddle with it, you probably know more than the average one by now!
Stu
 
Yes is the short answer, they should be checked after 50 hours.

As the engine is new the valves can bed in this bedding in will reduce the valve clearances. This wont normally show up as much of a problem unless you are calling for lots of power.

Tight tappets ulitimatley cause a loss of compression because the valves dont close.

but even if they dont affect compression at low revs at higher revs the engine wont breath properly, the valves will not be closed long enough to get a full charge of air compressed. This will cause a loss of power. Work out the angles and the effect on valve timing a few thousanths of an inch make on cam revolution - its very significant.

If the engine sounds very quiet at tickover I would suspect that the tappests are tight and need resetting.
 
I dont know whether the prop calc software can be used this way but messing around with the data you gave and using the 5kn boat speed, actual prop size and the actual revs, it implies that you are only putting something like 10 bhp into the water.

this would be roughly two thirds of what the beta engine power curve shows that should develop at 2200 rpm. the power given out by the engine should match the power need to make the boat go through the water at a steady speed so the implication is that the engione is devloping a lot less power than it should.

as I say, I dont know that the software can be used this way. I've tried to find a calulator which will say what bhp is needed to drive your boat at the 5kn but have failed. my guess fwiw is somewhere between 15 and 20 bhp.

I will be fascinated to learn what the proble is when eventually you solve it. make sure to let us know!
 
Thanks for all the advice so far theres a lot of good stuff there. For the ventilation question you can probably guess that I have spent a lot of time running with the covers off so I think thats OK. I'll check the tappets which is quick and easy and would explain everything but I would have thought that Beta or Kubota would have been aware if this was a problem. The manual says check at 800 hours. I did have a problem at one stage with dirt in the fuel tank but I have changed both filters twice since and they are now spotless. I am now sure the fuel is OK from the tank but I am going to check right up to the injection pump for the third time. Beta use horrible outer plastic convoluted tubes so you can not see the fuel lines. Is it possible for very fine particles to get past the filters. I was interested in the calc showing that the 2200 rpm with the 16 x 10 indicates a lack of power as well because this ties in with my distant memory that it was OK at launch. As I mentioned before the cavitation noise was very distinctive but I never heard it again. As a last resort if I find somewhere to dry out at the weekend I will try the 15 x 9 blades but I am not certain enough that this is the problem to warrant paying out for a lift.
 
the smaller blades should increase the revs even if the power is down. but given the amount of effort you've put into the engine side, I'd be very inclined to change the prop just to see. prop sizing does seem to be a black art rather than a science.

When you are motorsailing, does the engine speed up to its limit?
 
Sailing at 7.5 kts the revs increase to about 2400. If it does 3600 out of gear I would have expected it to be approaching that almost regardless of prop size. Is the gearbox binding somewhere. I presume the prop blades would always be deployed above a few hunderd rpm even if being moved by the water rather than engine.
 
KAM
it only takes a small amount of salt water to do this, go back to what I said, dont mess with the pump like you have been doing, (pin) take it off and take it to a proper injection system repairer. They will be able to check the delivery. Check the tappets (cheap and easy) check the stop mechanism isnt stopping the pump putting out and then take it to the workshop.
Stu
 
16 x 10 is the correct prop for 28hp, in as much as you should be able to acheive max revs - the issue is with the power.

if control cables are ok and the engine settings are ok, then look at the fuel system but a 100 hrs get the manufacturer to do it.
 
"If tappets tight then lack of compression and hesitant starting"

NOT SO this is very missleading advice! They can be 0 clearance when the engine is cold which would enable the engine to start and run and sound like a sewing machine at idle but not produce power, this is elementary basic engineering and any "engine man" knows it. Nowadays its taken for granted in a world of hydraulic tappets and its often negleted by modern mechanics when investigating ancient basic lumps - boat engines are VERY basic lumps but these little gaps matter.

They WILL close up in the first 50 hours of use - some manufacturers predict this when the engine is first assembled and set them wide.

I know of a case (NOT HERESAY) where a new JAP engine destroyed itself inside 20 hours because of incorrectly factory set tappets - its no red herring it DIRECTLY affects the power output - especially at high revs - which is what the trouble is.

By all means check for fuel starvation but that avenue seems to have been exhausted. Fuel injection pump failure at low hours is very rare as is injector failure unless the fuel is contaminated - easy to verify.


I spent 10 years of my life making and tuning ancient engines for Ford what do I know . . . . .

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Sorry matey, your reply shows a basic lack of understanding of how an engine works, the prob with these posts is that they end up in a slanging match with the aim of a poster being to show that they are an expert rather than trying to solve the prob. Read my post again, I said check the tappets, cheap and easy, before going down the route of more expensive things, if you had read the link provided by one of the other OPs then you would have seen a possible explanation as to why the pump had failed in that case. The OP seems to have checked the simple basic things and is now having to look for more exotic causes.
Stu
 
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