So I just bought a Mac X....

[Russ]

Can you open the throttle on the Honda without putting it in gear?
My Suzuki has a button in the center of the throttle arm that when pressed in, allows to throttle up without having the engine in gear.

I imagine the purpose of WOT is as mentioned, to allow unrestricted air flow.

Seeing Opie's compression tests, it makes me wonder. His are far from 199 and not all equal. Maybe it's not that indicative.
Don't overthink all this stuff. Replace the impeller and take the boat out for a test.

An engine that old would have gone through quite a few impellers and OO must have kept them all for nostalgia or some such reason.

[Tomfoolery]

Can you open the throttle on the Honda without putting it in gear?
My Suzuki has a button in the center of the throttle arm that when pressed in, allows to throttle up without having the engine in gear.

Yes, Russ, there's a short lever on top of the engine control that works the throttle. It's usually used for starting, and it will engage the choke when lifted all the way, though I usually use the little pull-out knob on the engine itself for the choke. Don't need to give it all that throttle that way, especially on an engine that's been sitting for 6 months without running.

[Drifter]

Don't overthink all this stuff. Replace the impeller and take the boat out for a test.

That's exactly what I'm thinking

Unfortunately I need to wait for the full housing unit to arrive, which could be a couple of weeks or so, even from Amazon (who tend to be much quicker than most others available here).

I don't think it's nostalgia, more a case of stocking up on spares impellers, as they are new, along with a new thermostat and a new internal anode.

What is not new is the thermal switch, which could be nostalgia or just keeping it in case the new one was an incorrect part. I almost did the same thing, put my old thermostat in a little plastic bag, with a note saying "This one no good but can compare with replacement". And then today a brand new one, complete with 2 gaskets, arrived from Japan! I literally forgot that I ordered another one.

Sometimes things ordered never turn up, so if it's cheap but important I sometimes order from 2 different suppliers. So now I have TWO spare thermostat, and my efforts at carefully cutting out some spare gaskets were somewhat unnecessary

Regarding WOT without being in gear, I didn't notice anything like that. I really should spend some time peering at that remote as I've barely even looked at it. I know it says something about a choke but I couldn't see quite what they meant, and she starts easily anyway (average of 32 centigrade every day here, about 90f)

Ah, just seen Tom's post. So the choke is pulling it all the way up? My throttle body is set much lower down, virtually have to touch your toes to put it in reverse (hence my panic last time while docking...)

[Be Free]

Can you open the throttle on the Honda without putting it in gear?
My Suzuki has a button in the center of the throttle arm that when pressed in, allows to throttle up without having the engine in gear.

I imagine the purpose of WOT is as mentioned, to allow unrestricted air flow.

Seeing Opie's compression tests, it makes me wonder. His are far from 199 and not all equal. Maybe it's not that indicative.
Don't overthink all this stuff. Replace the impeller and take the boat out for a test.

An engine that old would have gone through quite a few impellers and OO must have kept them all for nostalgia or some such reason.

You cannot open the BF50A throttle completely without putting it in gear. You cannot crank the engine unless it is in neutral. That's why you have to pop the throttle cable off and open the linkage by hand to perform the compression test.

The lever on on the remote control will increase the idle speed and engage the throttle solenoid when it is pulled completely up. It should only be used to start the engine and warm it up.

[Drifter]

You cannot open the BF50A throttle completely without putting it in gear

That explains why I couldn't get more than 5000 rpm out of it the other day

[Dougiestyle]

When you take off the impellor cover off, pay attention to which way the vanes are facing on the impellor, because you want them turning the proper way. I put a little bit of grease on the rubber when mine goes back together.

[Drifter]

OK, so today I tried doing a compression test, and replace the spark plugs whilst at it....

My compression tester is some cheap Chinese thing, and the gauge is not steady and does not hold, so had to get the Admiral to bump the starter while I peered at it, with clipboard in hand and looking very captain-like.

So some results... Figures are approx as the needle was bouncing around so I was just looking at the highest point it was consistently hitting.

Cylinder 1 - dry - 150 psi
Cylinder 2 - dry - 150 pis
Cylinder 3 - dry - 100 psi

Omigod

Oh wait, forgot to hold the throttle for that last one, try again...

Clyinder 3 - dry - 150 psi



So "low" but consistently low. Note this was bone dry and cold, with the engine not run for a week or two.

Tried again, this time squirting some 10-30 oil in there. Big thanks to OverEasy for that tip via DM Almost certainly not consistent with how much oil, but a squirt is a squirt. So...

Cylinder 1 - wet - 175 psi
Cylinder 2 - wet - 175 pis
Cylinder 3 - wet - 180 psi

That 3rd one, which I was at first worried about, seems actually the best one. Main thing is they all seem pretty consistent with each other.

An extra 25 psi by wetting with oil would suggest the rings are somewhat worn, and of course they're far below the official spec of 199, but overall I'm happy with this result.

They're all in the right kind of ballpark and they're consistent.

Not so great are the spark plug results. That bottom cylinder is running a little rich, and me and carburetors don't really get along

20210328_130008.jpg

By the way, last week when replacing the zinc under the tilt thingy, I removed some barnacles and stuff and these 2 springs fell out. Anyone recognize em?

[opie]

Drifter, let's ask Tomfoolery to reinstate his photos in his old link here

viewtopic.php?t=23259

The springs are for the tilt lock.

[Drifter]

Ah, so it's supposed to be spring-loaded? I'll have a look tomorrow, cheers

[Russ]

I wouldn't make much of the compression tests other than the cylinders seem to be somewhat equal which is good.
I'm far from an expert, but what I've read is you need to test with engine warm. Maybe that causes rings to seal better.

I wonder if there is a way to test engine temp externally. My Seadoo was overheating and shutting down. Turned out to be the sensor.

On another forum, similar issue, captain used a weed whacker plastic "wire" in the pee hole and up into the engine to clean out gunk. Also a suggestion was to blast water from a hose into the thermostat housing DOWN to the bottom intake.

I think flushing for an hour with that salt away stuff would probably be good PM anyway.

[Tomfoolery]

Drifter, let's ask Tomfoolery to reinstate his photos in his old link here

viewtopic.php?t=23259

The springs are for the tilt lock.

I’ll do it on Monday, as my photos are on another machine.

[Be Free]

I would not be concerned with the compression results. They would have been a little better when the engine is warmed up. You have normal, expected, and equal wear in all three cylinders. If you ever have to rebuild the power head a new set of oversize rings should bring it back to spec. I was worried about the third one until you mentioned you forgot to put oil in it.

You have now eliminated a head gasket leak as the cause of your overheating. All of the other causes are inexpensive and easy to fix. A small celebration is in order. (why don't we have a cake emoji?)

Check your plugs after the next trip. I see a combination of soot and burnt oil on them. You are getting a little oil in the combustion chamber because your oil ring is leaking along with the compression ring. Nothing you can do about that short of a major overhaul. Unless you are leaving a cloud of blue smoke behind you or a trail of oil in the water don't worry about it. The good news is the air-fuel mixture is (technically) not adjustable on your carbs. If it's running rich the problem is likely a sticking choke or dirty air filter.

You get extra points for so carefully marking the position of your plugs.

[Be Free]

Possible correction: the air-fuel mixture is not adjustable on the US version of your carbs. I don't know if the little plastic caps that cover the mixture screw were on all versions.

[Drifter]

All of the other causes are inexpensive and easy to fix. A small celebration is in order.

There is still the very real possibility that all the water channels are badly corroded and clogged with crud, which could require splitting the engine open to clean.

So no cakes just yet.

I will try running Saltaway for as long as I can before the water tub gets too hot.

If that doesn't work, hydrochloric acid... (heavily diluted, and not for long before flushing)

If that doesn't work then will have to try and find some gaskets and see about opening the engine. I think I will need to open the side water jackets anyway, to change the internal anode (trying to remember if there's just 1 or 2? Still waiting for the manual..)

As ever, you guys are keeping my spirits up, and have saved me a lot of ear-pulling (I shave my head )

[Jimmyt]

All of the other causes are inexpensive and easy to fix. A small celebration is in order.

There is still the very real possibility that all the water channels are badly corroded and clogged with crud, which could require splitting the engine open to clean.

So no cakes just yet.

I will try running Saltaway for as long as I can before the water tub gets too hot.

If that doesn't work, hydrochloric acid... (heavily diluted, and not for long before flushing)

If that doesn't work then will have to try and find some gaskets and see about opening the engine. I think I will need to open the side water jackets anyway, to change the internal anode (trying to remember if there's just 1 or 2? Still waiting for the manual..)

As ever, you guys are keeping my spirits up, and have saved me a lot of ear-pulling (I shave my head )

Have you determined that the temperature sensor is actually ok? Infrared thermometer reading at the sensor support the overheat signal?

Seems like someone mentioned the sensor earlier, but I can't remember if you've been able to verify it.