97 Hx Fresh Carbs More Problems

[robatoocc]

All I can say is WTF!!! I just rebuilt the carbs last week. Started it up and it ran fine. I took it out the day after I bolted the carbs back up and it was hauling ass like a brand new ski. Here I am a week later trading the Old HX for a for a jet boat with no engine and the b**** wont idle. It will idle fine if I give it gas through my primer kit. About a pump a second . And it will run fine when I give it anything over 1/4 throttle on its own. When I let off the throttle it runs for a second or 2 then stalls out on me. I have tried messing with the idle and the low speed adjustment. (Stock is 1 3/4) I guess I am going to be pulling the Mag carb off and checking the fuel pump and carb filter. I doubt I will find that they are clogged because the carb doesnt even have a gallon of gas through it. The pop off psi was around 50 psi right on spec when I had them apart last week. Both plugs are wet when I check them after it stalls so I am thinking it is getting fuel but not spark at idle. I trimmed the plug wires again just to be safe. Should I check the engine for a pulse/ vac at turnover rpm's? I printed out the manual from sdf but I am not sure how I should test for spark? Do these ski's have coils or just a stator? Any input would be greatly appreciated since I will be stepping up to a boat to bug you guys even more. Especially Timmy (and yes Tim that hole loved the JB weld )

 

[seadoosnipe]

Pop off....

Your pop off is not on spec....You should be seeing about 20 to 28 PSI on your pop off. This is why your going dead. Once you get it running past idle, pop-off pressure no longer matters.

If the pop off is way under, the needle valve will not close and it will flood the engine with fuel and bog down...........

Don't know where you got 50 psi as normal, but I can assure you it isn't.:cheers:

 

[robatoocc]

thanks

Ok so in your expert opinion can I get away without a rebuild kit when I take the carbs apart to check the pop off again and change springs? The diaphragms/ gaskets are less than a week old?

 

[robatoocc]

I Took the pop off numbers from a 96 HX from this chart.
I have a 97 HX but I was under the impression that 96's and 97's have the same 717 engine/ 38mm carbs
As you can see this chart is quite controversial.



MODELS POP OFF(min.) POP OFF(max)
1996 SP,SPI,GTS 21 37
1996 SPX,GTI,HX 40 56
1996 XP 27 39
1997 ALL MODELS (EXCEPT SP,XP) 27 39
1997 SP 21 37
1997 XP 36 40
1998 GS,SPX,GTS,GTI

 

[timmyboy76]

yeah from whats "listed" at other sources, pop-off should be, between 36-60 psi...:cheers:

Rab, ur outta control, check that "hole" bro, maybe the "weld" popped off. lsa=1.5, hsa=0, Sounds though, the "low"fuel circuit is outta whack.:cheers:

 

[seadoosnipe]

Pop off....

In your chart, it states the pop-off for the 97 models. It says that excluded the SP and XP, so that means your HX is in that category. Change to the shiny silver spring and that should give you a lower pop off around 25 to 32 psi............I'm certain pop-off is your problem.

High speed jet at zero and start with your low speed at 1.25-1.5

Yes, you can disassemble the carbs several times without a rebuild kit. Just as long as you don't damage the gasket surfaces.

I'd also like a link as to where you got that chart. I'd like to research it if it's from a source that is not running OEM specifications............:cheers:

 

[robatoocc]

Im pulling the carbs now. Ill have some readings in an hour or so. I am not putting them back on until I hear further.

The website I got the #'s from is

lists 36-60 psi That is a HUGE margin for error.

So im looking for something between 25-32?

Timmy JB Weld FTW.

 

[timmyboy76]

hey, check that "site" but not the "carb reference" and it'll show a table to the size of n/s and what springs will give you psi. think you got 1.5, so the black or "longer" silver spring will/should set you in that "zone".

What a FTW....i'm a tard, on this pc lingo..:ack:

 

[robatoocc]

ftw

FTW= For The Win

I have the carbs in the nice cool basement. Just rebuilt my pop off gauge ill have some #'s up shortly.

Thanks for all of the help. You guys are awesome.

 

[Dr Honda]

Hey Snipe…

Don’t take this the wrong way… and I’m not telling you your biz… but the jetting, pop off, seat, and needle settings are different between the 720 engines for different years, and different hulls. The 97 HX should have a 36-60 pop-off per the factory service manual. (1.2 seat, 130 main, 75 pilot, 1 ½ idle, 0 high)

 

[robatoocc]

readings

OK I re tested the pop off and it was just under 50 psi. I have an assortment of springs I was swapping to try to get down to 30 or so. None of which were short enough. I ended up cutting 1 coil off my smallest spring and now I am down to about 34-36 psi. With my idleing problems should I be looking for the lowest possible pop off psi around 36 or keep it in the middle around 45-55? Lemme Know. These Puppies are apart once again on the table. Im not bolting them back up until I know for sure what the correct setting should be. Lemme know. I have the laptop in the basement just out of reach of flying wd-40

 

[timmyboy76]

between 36-60psi. you aint gonna achieve under 30psi with a 1.2n/s. Stay with original spring you had last week, when run'n fine, and turn the LSA another 1/4turn or until it has enuf to idle, and/or turn idle up /down some..

Rob, never cut the spring, when ski not in use, the spring, or even when in use, then spring will turn in its housing, thus causing a different psi. One time it'll be 35psi, next its pinched and wont pop at all.

 

[robatoocc]

Pop off

Well the ski didnt idle yesterday. So what am I to do? Snipe is telling me I'm to high and I have to get the pop off lower. lists me between 36-60. To help this puppy idle do I want to be low like 40 or higher like 50? I am pretty sure that it is flooding out on me at idle. Like I said when I pull the plugs after it stalls they are soaked. I tried new plugs (gapped) to no avail and trimmed the wires. I ground the pto plug and it sputters on the mag and vice versa so I am under the Impression I have spark. When I am doing the pop off test I should have the LS set to 1 1/2 correct ? The HS is set to 0

 

[timmyboy76]

pop-off is done with carb apart, whether lsa/hsa are in the carb or not. If ur flooded, then pop-off to low, or needle is leak'n, but cant be flooded, since it idles when you "prime" it every other second.

 

[robatoocc]

Psi

Ok so both carbs are popping off between 48-50 with my smallest springs. I did the 10 psi leak test on the fuel pump and that is holding no problem. Id like to get this taken care of today. Should I run to napa and get a couple smaller springs to lower the pop off to the high 30's? Basically I need to know if Lower Pressure pop off would help with the flooding at Idle?

 

[timmyboy76]

no napa

doesnt matter the "size" of spring, but what gram they are. Need to use he ones from the rebuild kit/mikuni springs.

should be if you dont have the "oem" one, are...little dull spring, black, tall dull spring, and gold springs.

with 1.2n/s, should install the "black" spring or the "dull silver" spring (has opposite coils than the other springs)

 

[robatoocc]

Offing Myself

pop-off is done with carb apart, whether lsa/hsa are in the carb or not. If ur flooded, then pop-off to low, or needle is leak'n, but cant be flooded, since it idles when you "prime" it every other second.

Well I know the needle is not leaking, it is holding pressure no problem. No bubbles coming from the needle or anything. I am going to get some smaller springs I guess and see if I can get the pop off to 40 or so then bolt it back up and see if it will idle. Your right about my flooding theory if I have to prime it then I have a lack of fuel. The only Other thing I can think of is not enough spark at idle. How can I check that? I remember reading somewhere about unplugging the harness coming out of the front engine cover. I am getting ahead of myself for sure seeing as how the carbs are not back on the ski yet.

 

[robatoocc]

doesnt matter the "size" of spring, but what gram they are. Need to use he ones from the rebuild kit/mikuni springs.

should be if you dont have the "oem" one, are...little dull spring, black, tall dull spring, and gold springs.

with 1.2n/s, should install the "black" spring or the "dull silver" spring (has opposite coils than the other springs)

Yeah I bought the Genuine mikuni kit. It came with a short gold spring and a longer Silver spring. The springs that were in the carbs were the short gold spring so I put the new gold ones in from the rebuild kit. With the silver spring it wont pop off until about 55 psi. With the gold ones I am getting 48 psi.

 

[timmyboy76]

Yeah I bought the Genuine mikuni kit. It came with a short gold spring and a longer Silver spring. The springs that were in the carbs were the short gold spring so I put the new gold ones in from the rebuild kit. With the silver spring it wont pop off until about 55 psi. With the gold ones I am getting 48 psi.

aint call'n you out stud, but those read'n might be backwards. The gold spring is rated at 110gm, and silver, depend'n which one, are 95gm/65gm, where the black is 80gm.

 

[robatoocc]

I understand that although the silver spring is a couple of mm longer it might not be as strong as the gold one with tighter coils BUT I did the pop off test with the 2 different springs in the kit and a third that was OE and the lowest pop off I got was with the newest gold spring. The OE gold spring was a few psi higher and the silver one was up around 55+psi. Right now on both carbs I am right at 45 psi so I am going to bolt the carbs back on and pray. I basically did nothing today but take the carbs out and play with them. Since the rebuild kit gold springs are back in the carbs. We shall see.

 

[timmyboy76]

dont go tossing those oem springs, but if you must, i'll shoot you my address via pm.

 

[robatoocc]

Well I did not opt to throw new gaskets on the carb/intake so I put some gasket maker on each side of the gasket a bolted it down. Tomorrow I'm gonna fire it up and see what happens. Thanks for all the input everyone.

 

[robatoocc]

Ok here I am on day 2 and I am getting no love from the rotax. I still have the same problem getting the engine to idle. When I had the carbs out/apart yesterday I even took off the H & L Jet cover plate and checked to make sure that the low speed jet was not clogged. I took the fuel filter off and dumped the fuel and ran the starter and watched the carbs suck/ fill the fuel filter back up in under 4 seconds. While I was searching for problems I took the power box apart expecting to find some corrosion. It is still 100% water tight. All of the components are still nice and shiny so I am thinking the electrical system is not my problem. The only corrosion I found was on the sensor between the spark plugs that has a brown wire coming off of it. Im guessing that it is only temp sensor. I cleaned it up to no avail. I really need to get this thing running or Ill be parting it out soon.

 

[custompartsguy]

how about the filters in your carbs? If your tank is clean and filter and a good feed line, how is your selector switch? if you switch to reserve does it get any better? If the selector switch is fine and you get proper fuel feed to your carbs but still have the starvation for fuel the only other thing is your carbs since you stated it would run fine if you hit the primer every sec or so that means it would most likily be a fuel starvation issue. How do your fuel lines look?

 

[custompartsguy]

in cleaning the carbs did you use any metal objects to clean out the holes?