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Aquacraft .18 engine problem

Old 08-12-2007, 02:26 PM
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kyle_yokomo
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Default Aquacraft .18 engine problem

Hello I have a Miss Vegas with the Aquacraft 18. I am having engine trouble and I cant figure it out. The motor starts just fine, I launch my boat and it runs great for about a minute and then the engine boggs down real bad like Im running half throttle. Sometimes it boggs down for a second and then picks back up to full speed only to bogg down again a few seconds later. I am running the engine on the rich side so to lean isnt the problem, although I tried leaning it out a bit to see if it would help but it didnt help the problem.

Heres what I have tried to fix the problem, I replaced the stock fuel tank with a Sullivan tank, I replaced the fuel and pressure tubing, I tried a different glow plug, And visually checked everything for leaks or anything that might seem wrong.

Does anyone have any ideas on what else I should check? Thanks

Old 08-12-2007, 02:43 PM
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Sean Bowf
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Default RE: Aquacraft .18 engine problem

From your original desciption, I would have guessed a fuel system pressure leak, until I read that you already replaced the tank. So you had the problem with the original tank and the new tank?

What fuel are you using, and how many turns out is your high speed needle? Have you tried another bottle of fuel?

What I have seen, for fuel mixtures, is that the engine will surge when running lean (you will hear its RPMs change in the straights) and it will seem to not reach full speed if too rich (like the last half of your throttle movement has no affect).

How hot is the engine running?? Can you touch the head when you pull the boat from the water, or is it too hot to touch (be careful). If you can touch it, how long can you hold your fingers on it?

Sean
Old 08-12-2007, 02:51 PM
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kyle_yokomo
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Default RE: Aquacraft .18 engine problem

I am using Traxxas 33% I am using this fuel in my Proboat hydro and it runs fine. I am 2 turns out on the high speed needle, and the engine temp is between 115 and 120. When I start the engine, you can see alot of smoke from the exhaust and fuel looks like its spitting out of the carb?
Old 08-12-2007, 03:12 PM
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Sean Bowf
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Default RE: Aquacraft .18 engine problem

I know different engines, different altitudes, running different fuels, different plugs, etc...will require different fuel mixtures, but 2 turns out sounds pretty lean to me.

The temp reading, how are you getting it, and where on the engine are you getting it from??

The temp reading, if at the plug, sounds pretty cool if you are taking it as soon as the boat comes out of the water, which would contradict the boat running lean.

I would try to back the needle out to about 2.5 turns, and see how it runs, then work your way back in an eighth turn at a time to see if you can find a spot it runs well again. (if it does not plane out well, bring it back in, adjust, relauch, later, rinse, repeat).

I have 2 stock MVs in the house, one is set at 2.5 turns out, the other is at is a little under 2.5 turns. I now I have got different MVs to run will at anything from 2.25 to close to 3 turns out...

Sean
Old 08-12-2007, 03:26 PM
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kyle_yokomo
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Default RE: Aquacraft .18 engine problem

Im using a O'donnell temp gun so the readings are pretty acurate, although those temp readings were done on only a couple minutes of running, before I brought the boat back in because of engine issue.

I will try to richen it up some to 2.5 turns like you said. Thanks for your help Sean
Old 08-12-2007, 04:14 PM
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Sean Bowf
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Default RE: Aquacraft .18 engine problem

NP Kyle, I hope you get it figured out.

The temp gun you are using is probably more accurate than mine. I am using a cheapy harbor freight one. But what I was trying to get at when I asked how you got the reading, is where on the engine you are getting the reading, and how fast after shutting down.

There was a discussion here earlier, and from that discussion, I think folks are taking readings from different parts of the engine (BTW, I don't think we ever came to a consensus on what/where is best). I point my temp gun (more like a keychain fob) right at the top of the glow plug as soon as I can rip the cowl off it after I stop.

I think some folks are reading the temp from the cooling head itself, and not the plug. I don't have enough experience to say for sure what is best...but as I mentioned, I get mine from the plug.

Sean
Old 08-12-2007, 10:09 PM
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kyle_yokomo
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Default RE: Aquacraft .18 engine problem

I tried the boat with 2.5 on the high speed needle and it wouldnt even get on plane? I then started to lean here out 1/8 at a time, I got just inside 2 turns out on the needle before she started to run good and of course it did the same thing. I think I got a bum engine? Anyway I have a new Aquacraft .18 I havent used yet so I think Ill put that in and see if it wont fix my problem[]

Oh yeah I always take the temp right on top of the glow plug, I pretty sure this is wear your supposed to do it. Thanks for trying to help Sean, but unless you can think of anything else that could be causing my problem, Im going to try a new engine.[8D]
Old 08-12-2007, 10:21 PM
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Sean Bowf
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Default RE: Aquacraft .18 engine problem

Hhhhmmm....

What prop are you using, how deep is it, and at what thrust angle do you have it??

I figured all this was set up correct, because you said you had it running right for a minute before it came off pipe/plane...but thought I would ask.

I know if the prop is too deep, it will rev up in the turns, and then get a little into the straights, then fall off pipe/plane again. Then it might do it again in the next turn.

Good place to start with a Y535 in calm water is a flat thrust angle (no up or down angle), and a depth of about 3/4 of an inch from center of strut barrel to bottom of hull (where the stuffing tube enters the strut).

Like I said, sounds like you have this stuff set up right, but just figured it might be worth a look.

Sean
Old 08-13-2007, 08:08 AM
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Default RE: Aquacraft .18 engine problem

Also better take a look at the piston on the ex port side.......... sounds kinda like we leaned out a new engine too soon.
Old 08-13-2007, 08:45 AM
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kyle_yokomo
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Default RE: Aquacraft .18 engine problem

Im running a Ocura Y535 and Im 3/4" from bottom of transom to center of prop, nuetral angle

f16man has this happened to you? and what should I be looking for when I get the engine apart?
Old 08-13-2007, 09:13 AM
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Default RE: Aquacraft .18 engine problem

i pretty much had the same problem with my supervee some one told me to go to three turns out, i did and it was fine, now iam going back in at 1/16 turn at a time, there boat motors you cant compair to land motors mine is also throwinf a lot of smoke and raw few out of the water,,and it does take about 15 ft to ger her on plane,,and if i slow down to much in a turn it takes about 10-15 ft agian,, wnad remember weather affects the settings,,,when you ger it running right,, it flys,,,
Old 08-13-2007, 09:25 AM
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Default RE: Aquacraft .18 engine problem

I had the same problem with my .18 and you know what solved it and made me feel like an idiot? I richened it up! that was it....

I had the same symptoms as you. Ran fine for a few minutes then intermittently bogged, then went into full "bog" mode.

I richened it up a 1/16th at a time and ran it. It began doing it less and less until I hit that sweet spot and no more bog.
Old 08-13-2007, 10:18 AM
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Default RE: Aquacraft .18 engine problem

we seen it happened here quite a few times, do not only rely on the smoke, depending on type of fuel even when running too lean you may have a good trail of smoke.

Your P/L should still have their original color ( or close to it ) if what you to be brass and chrome is now a dark black/blue and you can see scuff marks inside the Liner and on the Piston, well it means that you need a new one, it ran too lean.

Start at 3 turns out on the HSN than you make your way in 1/16 at a time. Note that if your P/L is burnt, it wont matter where you put the HSN at, its too late.

Ensure you have a good flow of water coming out in the curves and in the straights, we had that happened to one of our friends because something was wrong with the pickup hole.

This is what it should not look like.

Dan.
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Old 08-13-2007, 11:03 AM
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n00bie
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Default RE: Aquacraft .18 engine problem

my husbands boat was running great yesterday, but then his water tubes melted to the pipe, so his motor over heated and now it is shot. I can not get a motor till early september, any suggestions on parts that will be needed to repair or rebuild the existing motor to at least get her back in the water until a new motor arrives?
Old 08-13-2007, 11:18 AM
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Default RE: Aquacraft .18 engine problem

You Should only require a Piston and Liner if everything else is ok.

ensure you get some good silicone water/fuel tubing to replace his water lines, I have one of my fuel line and my exit water line touching the exhaust header and not one of them have melted yet in 2 years.

Dan.
Old 08-13-2007, 04:44 PM
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Default RE: Aquacraft .18 engine problem

Here's the Piston and Liner
http://www2.towerhobbies.com/cgi-bin...?&I=LXMMR4&P=Z

Glenn
Old 08-13-2007, 04:51 PM
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Default RE: Aquacraft .18 engine problem

dont forget the con rod
Old 08-13-2007, 05:26 PM
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Sean Bowf
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Default RE: Aquacraft .18 engine problem

ORIGINAL: cwaterhunter
dont forget the con rod
yep yep... But of course they are out of those until September too...

Sean
Old 08-13-2007, 07:00 PM
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Default RE: Aquacraft .18 engine problem

I don't want to start a debate here, to be on the safe side replace the Con rod BUT it is very likely that you can do without replacing it.

Dan.
Old 08-13-2007, 07:26 PM
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Default RE: Aquacraft .18 engine problem

Thanks for the quick answers. I have the piston and liner ordered, should be here wednesday or thursday. Have a whole motor on back order (for backup), and made sure that the boss has silicone tubing on order also. Working in a local hobby store has its benefits. But it doesnt ensure that I get parts I need when I want them RIGHT NOW

Anyone know of hobby stores locally (western washington state) that might carry miss vegas parts right on their shelves?

Old 08-13-2007, 07:29 PM
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Default RE: Aquacraft .18 engine problem


ORIGINAL: Dan S

I don't want to start a debate here, to be on the safe side replace the Con rod BUT it is very likely that you can do without replacing it.

Dan.
very well could do without it,, but why take a chance?,,, its up to them....
Old 08-13-2007, 07:32 PM
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Default RE: Aquacraft .18 engine problem

Well, looks like I was wrong. I fought the bogs all afternoon and never got it to straighten out. it bogs when its rich, it bogs when its lean...

I changed the plug, pulled the head, the piston sleeve look brand new.

It seems that if I let off the throttle when it starts to bog, it will stay running but as soon as I gas it and hold it, it starts to bog and within a few seconds, shuts off.....
Old 08-13-2007, 08:02 PM
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kyle_yokomo
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Default RE: Aquacraft .18 engine problem

OK I took the engine apart and the piston and sleeve look good. So Im thinking now that maybe the carb isnt sealed to the block, and that a small air leak might be between the carb and block?

Also I am using the stock coupler that connects the manifold to the pipe, well Ive been reading that the stock coupler is junk? If there is a air leak in the coupler could that be causing the problem?
Old 08-13-2007, 08:08 PM
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Sean Bowf
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Default RE: Aquacraft .18 engine problem

Its only a problem if it is split through. If it is in tact, then it should not be causing your problem, but will burn through eventually...but pretty much all of them do.

I have had decent luck with the MAC half inch coupler.

Sean
Old 08-13-2007, 10:10 PM
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Default RE: Aquacraft .18 engine problem

Oh man I think I need a GPS cause it looks like were trying to help 3 different people at the same time and now I don't know who's got what problem or what was solved[&:][&:][&:]

Lets try anyway:

Kyle,
even if the coupler was split (which has happened to me more than once) you would still be able to run, you will here the sound change and see the loss of power but still run. where is your LSN set? check to see if she is flush, you can bring her in 1/8 of a turn. Check your pressure line at the pipe, check the vent line in the tank and last thing when you checked the P/L when you turned the engine over was the piston pushing the liner up or could you go through the full stroke without the Liner moving?

Webdr,
same thing.


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