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  1. #1

    Newbie questions about holes in 96 Challenger and more...

    I purchased a 96 Challenger last week. I'm a total newbie to jet boats. Our only prior boat experience is a 13' inflatable with a 25hp Yamaha outboard which we'v had a lot of fun with over the past year. I have a few questions after the Challenger's maiden voyage on Saturday:

    Can someone tell me what these small holes are for in the hull?

    The airbox appears to have been drilled out for better breathing. It seems like that would make it more prone to suck in water if somehow water splashed in the engine compartment. Is there really any performance benefit to drill out the air box like that?

    I use the boat in the ocean. After flushing the motor, is it necessary to spray the lube in the carbs and then spray some in the spark plug holes if you plan to use the boat within the month? Or is the spraying of lube in the engine just for long term storage?

    We rode it pretty hard for 2 hours on Saturday. Twice the motor died. Each time was when we throttled down after running it hard. It started right up after a few seconds sitting. Nothing happened at first when we pushed the start button. But after waiting a few seconds the engine turned over when we hit the start button and it started up immediately. Does this sound like a problem that needs to be checked out or do these 2 strokes sometimes cut out when you cut the throttle?

    What is the purpose of the VTS lever? I know it directs the jet flow up or down to adjust the pitch of the boat. However, I didn't really notice much change in anything moving the lever up and down while running. Only me and my son in the boat at the time. I just saw this in Google now: "it uses a variable trim system that allows the pilot to adjust the angle of the waterjet down for incredible hole shots, up for maximum top end."
    Is "hole shot" the time to get to plane? If so, then is the proper operation of the VTS lever to have it in the down position when you start to accelerate and then move it to the up postion once in plane for best top speed? If that is correct I would take it that you would always leave it in the full up position when at plane?

    Is there away to make this thing any quieter??? (Short of buying a 4 stroke...) There is some sound aborbing material in the engine compartment but much in there is not covered. Anyone have any tips on making it less noisy specially when just going at a slow speed on the way out of the harbor?

    Anyone know how many gallons per minute the jet is pumping out at WOT? Yeah, that is a weird question but my son keeps asking me.

    Is it bad for the boat to run it for an extended period of time at WOT?

    Thanks for any tips and advice!
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  2. #2
    I guess the proper name of the black air box is the air intake silencer. So I take it with all those holes drilled in it it does no silencing. I wonder if that accounts for a lot of the noise I hear? Anyone?

  3. #3
    1996 Sea Doo Challenger (787x1)
    Join Date
    Aug 2007
    Posts
    69

    1996 Challenger

    Looks like someone thought he could improve air flow over the factory design...having seen the openings under the rotary valve, and the carb throats, I don't think the OEM design was significantly restrictive. The holes that face upward probably do make it easier for splashed water to make it to the intake, if the situation developed.

    I've also got a 1996 Challenger, and it has similar holes in what I assume are stringers, down there in the bilge area. I'm a newb to boats, so I can't offer any speculation on what purpose they serve. At least one of the openings in my boat has a rubber grommet--a grommet, not a cap--in it. That leads me to assume Seadoo intended the holes to be open...??

    AFA noise, I read a post somewhere in which a guru-type (Bill O'Neal, possibly) called the 1996 Challenger "the loudest boat Seadoo ever made." One thing you'll notice is the *entire boat* resonates with engine noise---all around you. The engine noise runs forward from the engine compartment thru the big voids on either side, and resonates in those cavities. I've achieved remarkable success in muting the noise, and restricting it to the engine compartment--localizing it there, if you will--by blocking those openings with floor underlayment padding...not a permanent solution, but it's worked well enough to let me know I'm going in the right direction. With the openings blocked up, the predominant noise above 35 MPH now is the wind, not the engine.

    The trim control on your boat may be inop...mine was. Seadoo designed a somewhat complicated mechanical interlock system on the VTS, which supposedly centered the pump venturi when the bucket was moved from Forward to Neutral, to make the reverse bucket work right. On my boat, the system no longer moved the venturi, regardless of the F-N-R lever position. I tried adjusting the linkage per the FSM, and it worked for one ride...then failed again. I ended up slackening the "centering" cable completely (essentially removing it from the system), and permanently bound the "sliding blocks" together with cable ties...so my venturi stays trimmed up or down, regardless of the F-N-R lever position (I have to use my noggin, instead of relying on Seadoo ...but my trim works now!).

    AFA fogging carbs and cylinders (thru the plug holes), I've seen gurus/heavy hitters post time and again to do it "every time", even if you plan to drive it the next day...seems to be considered the single most important preventive maintenance measure you can take, for engine life. I'm using a trigger spray bottle with Marvel Mystery Oil.

    BTW, that orange plastic thing with two metal blades is where you park your plug leads, when cranking engine with plugs removed...if you don't ground them, a voltage surge can back-flow thru the MPEM and blow the bilge pump auto-water sensor circuit (causing the pump to run continuosly, regardless of panel switch position or absence of water in bilge)...according to a Bombardier service bulletin. My boat was missing the ground piece, and the bilge pump circuit has been re-routed, so we can probably guess that someone did the deed on mine .

    I don't know the answers to your operating questions on 2-cycle engines...still too new for me.

    No idea on how many GPM the pump pushes...tell him "Lots!"

    Have you GPS'd your speed yet? I've gotten a smidge over 45 MPH...engine is a recent SBT rebuild, with a Skat-Trac Swirl impeller.

  4. #4
    Quote Originally Posted by Steve762us View Post
    Looks like someone thought he could improve air flow over the factory design...

    I've achieved remarkable success in muting the noise, and restricting it to the engine compartment--localizing it there, if you will--by blocking those openings with floor underlayment padding...

    The trim control on your boat may be inop...

    Have you GPS'd your speed yet? I've gotten a smidge over 45 MPH...
    I've seen the stock air boxes for sale cheap. I will pick one up and put it in. Even if it slightly reduced acceleration I would prefer that if it reduces noise. The 4 intake holes look large enough for the 2 carbs IMO.

    I noticed the large openings too from the motor compartment along side of the boat. I though about stuffing styrofoam blocks in there to block the noise. Sounds like you tried something similar with success so I will look for something to stuff in there to also keep the noise in the rear so the entire boat does not function as an echo box for the motor!

    My trim does work. All my controls are very smooth. I just had no idea what to do with the VTS. Next time out I will clock it with the VTS pointing the jet up. That should keep more of the boat out of the water and result in higher speed due to less drag. No biggie one way or the other but I like to know how and why everything works.

    I clocked mine with 2 adults inside at a hair over 41mph with a GPS. What was strange was that at the end of the day the GPS showed 54 MPH as max speed. I think that was just a glitch as when I looked and saw 41 we were at the smoothest part of our run so I doubt we got going faster than that in the choppier water further out beyond the breakwater wall.

    For the price we are quite happy with the boat. Looks clean and is fun to zip around in. Only thing I really really really want to do is get the noise level a little lower. Oh and yeah, get a pair of goggles. My eyes were watering too much from the wind using only my regular glasses!

    Know of any inexpensive over glasses goggles that do a decent job?

  5. #5
    "We rode it pretty hard for 2 hours on Saturday. Twice the motor died. Each time was when we throttled down after running it hard. It started right up after a few seconds sitting. Nothing happened at first when we pushed the start button. But after waiting a few seconds the engine turned over when we hit the start button and it started up immediately. Does this sound like a problem that needs to be checked out or do these 2 strokes sometimes cut out when you cut the throttle?"

    Pilotsmith,
    This can be a bad sign on a 2 stroke. It "could" mean the engine was starting to get a little tight(hot). I've had a 70 hp outboard do the same thing. The water pump wasn't putting out like it should have. The engine revs started to come down and it finally stalled. I sat a couple of minutes and it started back up. Went 1/2 mile and it stalled again, this time I was towed back. Had to rebuild the powerhead . Check your water supply.

    Mike

  6. #6
    1996 Sea Doo Challenger (787x1)
    Join Date
    Aug 2007
    Posts
    69
    Quote Originally Posted by PilotSmith View Post
    I noticed the large openings too from the motor compartment along side of the boat. I though about stuffing styrofoam blocks in there to block the noise. Sounds like you tried something similar with success so I will look for something to stuff in there to also keep the noise in the rear so the entire boat does not function as an echo box for the motor!
    I've done some of that, too...I found some large (~2 cu ft) styrofoam blocks at a Gander Mountain store. I cut em up with a Weller gun and stuffed them up along both sides...with regard to linkages, hoses, and wiring harnesses, of course.

    Reference Mike's post on overheating...the seller had a bolt inserted into the transom coolant outlet on my boat...he told me to remove it when running, but replace it for flushing. The first time I took it out, I forgot to remove the bolt, and the engine apparently did overheat, and shut down after about 30 minutes. The flow that exits that particular fitting exits the cylinder head just "downstream" of the temp sensor...so with the bolt blocking flow, that part of the head had no water circulation.

    There should be fitting screwed on the thru-hull fitting for that coolant line, similar to a garden hose quick-release (reduces the outlet diameter to about 1/4"). The thru-hull should not give a full-garden-hose diameter flow, in other words. You might want to check that fitting--it's about a foot inboard from the scupper valve, on transom.

    Yes, you need eye protection for everyone aboard...for sure!

    I'm no pro on trim, but as I understand it, trimming DOWN is useful in rougher water, and to reduce porpoising. Trimming UP is supposed to provide max speed, depending on conditions, etc...but will tend to accentuate the boat's reactions to water conditions, ie more porpoising, more air when crossing wakes, etc. I don't know which would be better for getting up on plane quicker...

  7. #7
    I don't like not having a temp gauge. I've been planning to put one in as I don't really trust just having a buzzer go off as you never really know if the buzzer will work. You do know if a gauge is not working. Anyone have any tips on doing that? Hope it is not an over heating issue.

    As far as for sound, I picked up some polyurethane pour foam. I plan to stuff a trash bag in the side void and pour the foam in. That should expand to make a custom fit plug to seal off that area and keep sound from traveling and echoing past the engine area. At least I think it should work in principle. It is the same stuff you use to fill hulls for bouyancy. West Marine wanted $100 for enough to make 2 cubic feet of foam. Got it from a local eBay seller for $25. I just happened to be about 5 miles from his shop so I picked it up with no shipping. He has it listed for $28 on his web site ( http://www.jgreer.com/Foam%20Page.htm ) I'll post how it works out. I can't believe West Marine wanted $100 for the same amount of foam!

    P.S. I just tested my overheat sensor. The sensor works but the buzzer is dead. I just ordered a replacement buzzer. For now I will connect a red LED in line with the buzzer so that if the buzzer ever fails, or is not loud enough to hear, there will be a visual overheating warning. Eventually I'll probably put in a real temp gauge.

  8. #8
    Just a thought do they have this area open to get air into the engine compartment???? I would look into it before closing it off!

    I know nothing about this boat like I said just a thought.

  9. #9
    Quote Originally Posted by Mandoo View Post
    Just a thought do they have this area open to get air into the engine compartment???? I would look into it before closing it off!

    I know nothing about this boat like I said just a thought.
    Good thought but no, there are two large intakes in the rear of the boat for the motor.

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