My engine is fouling a set of sparkplugs by the end of each day of riding? (SOLVED)

[LMnsr]

Im going to try one last thing before i replace the engine. Im getting two carb rebuild kits and replacing all the engine gaskets then tuning the carbs. If it doesn't run well after that i will replace the entire engine.

Might be a $200 fix instead of a couple thousand.

I will update the post as soon as Im so far

Thanks guys

 

[Vumad]

Im going to try one last thing before i replace the engine. Im getting two carb rebuild kits and replacing all the engine gaskets then tuning the carbs. If it doesn't run well after that i will replace the entire engine.

Might be a $200 fix instead of a couple thousand.

I will update the post as soon as Im so far

Thanks guys

Sounds like a bazooka fix to a shotgun problem.

Pull the motor. Visually inspect everything. Do a leak down test on the motor. Check the compression.

Fully dismantle and thoroughly clean carbs, both sides including the fuel pumps, including the intake to inspect the reeds. Clean all carb parts in a soak like "Chem-dip", be sure that your throttle shaft bushings are not leaking (if they are, you can soak the whole carb, chem dip would otherwise damage bushings or o-rings), blow out all passages with compressed air, clean the venturis with nylon wire (not metal), reassemble using only genuine mikuni parts. Replace needles and seats even if they look good. Test carbs, not just pop-off but make sure they are not leaking. Replace reeds if any doubt.

Drain the fuel tank. If any excessive debris or any possibility of water, don't use the fuel. Inspect fuel lines, flush or replace if excessive debris. Replace fuel filter regardless. test or replace one-way valve

Open e-box, inspect for any possibility of moisture, same goes for the stator cover.

check all battery cables, replace as necessary

make sure water routing is correct.



On a ski that has never ran right, bought used, that has been mostly sunk, there's a lot of potential for small problems. Just check everything. While the motor is out, check your hull and secure your hood. It's worth the effort.

Every motor I have ever owned has been 10+ years old. Good even compression and lots of power. The only motor I had issues with is my superjet, and I couldn't figure it out, except it had a case leak. Even then, it still ran pretty well, it just had white plugs.

Replacing the motor is pretty extreme. There has to be someone you can take it to before you start throwing thousands at it.

 

[LMnsr]

Sounds like a bazooka fix to a shotgun problem.

Replacing the motor is pretty extreme. There has to be someone you can take it to before you start throwing thousands at it.

Thanks for this reply. I wil definitely check everything. I two carb rebuild kits and a top end gasket kit on the way. As soon as i have them i will start working on it. I will update this post

 

[Larry]

don't forget to order the gaskets that go between the carb and the intake manifold. They are not included in the carb rebuild kit. If you are taking off the intake manifold, then there are more gaskets that need to be replaced. Since shipping takes a while to get to you, make sure you order everything you may need, so you are not down waiting on a gasket.

 

[LMnsr]

I should be getting the gaskets and the rebuild kits today, let's see..

I have a few questions before I start.
how much torque should be used on the head bolts? and are there are any other torque specs i should know about.
also what would be a good starting point for the carbs? i live at sea-level and water temps average around 79-80 degrees

thanks

 

[Quinc]

 

[Quinc]

Test carbs, not just pop-off but make sure they are not leaking.

I am having an issue with my carb getting too much fuel in the midrange. How do you check if a carb is leaking?

 

[Vumad]

A leaking fuel pump would probably make it lean, not rich, but I'm not completely sure about that. I would raise the popoff to lean out the mid range.

By test the carbs, they should hold 10psi for 10 minutes. If not, Spray silicone, wd40, whatever around the pump body to test the o-rings. Or just clean and rebuild. Still test though. I put brand new sbt kits in my carbs and my popoff was right but my fuel pumps leaked. Their o-rings are smaller than mikuni and leak.

 

[LMnsr]

Last night we worked on the engine and found a couple of things.
I now know what jetting I have. it is 135(big) and 20(small)
While rebuilding the carbs there was white silicone debree in the filters in both carbs. plus the front carb was missing a gasket.
I replaced the silver springs with the gold ones that came with the kit.
The carbs are now set to the factory settings that i found in the superjet service manual.
(please let me know if this is a good place to start off)

I also found out i don't have carbon reeds as it was advertised.
(correct me if i'm wrong)
I checked the gas tank today and there was white pieces of silicone in the gas and even a piece of foil that comes on 2stroke oils.. I saw that there was silicone on the gas cap from the inside with a piece dangling off .. i removed it and washed the tank from the inside with water and let it to dry out.

When I inspected the head gasket a bit closer i noticed the silicone that was put there between the gasket and the head was completely blocking some of the water passages.


we cleaned up the cylinder best we could and reassembled the engine with the new gaskets.


Now I just need to seal the trim cable hole in the tray, wash the headpipe/pipe since they have a lot of carbon buildup and put everything back in to test it out

To be honest I feel a lot better about the engine/carbs now

 

[LMnsr]

Forgot to add that i inspected the ebox and one of my positive wires was so corroded it just broke off and the nut crumbled. thankfuly the screw wasnt too corroded so i managed to fix it.

 

[Quinc]

You DO NOT want to run the Stock recommended jetting!! That is for a 100% stock engine. You will want to start with a little richer jetting then what your exhaust pipe manufacture recommends.

Edit: Read back through your thread and see you have a bpipe. Here is the jetting per FPP:

Main Jet: 135 (130 stock)
Pilot Jet: 70 (stock)
High speed screw: 1 2 turns out from closed
Low speed screw: 1 1/4 turns out form closed
Needle & Seat: stock (55 psi)
Spring: 95 gram (You probably have a 115g in there)

 

[Vumad]

Last night we worked on the engine and found a couple of things.
I now know what jetting I have. it is 135(big) and 20(small)
While rebuilding the carbs there was white silicone debree in the filters in both carbs. plus the front carb was missing a gasket.
I replaced the silver springs with the gold ones that came with the kit.
The carbs are now set to the factory settings that i found in the superjet service manual.
View attachment 259471 View attachment 259472 (please let me know if this is a good place to start off)

I also found out i don't have carbon reeds as it was advertised.
View attachment 259473 View attachment 259474 (correct me if i'm wrong)
I checked the gas tank today and there was white pieces of silicone in the gas and even a piece of foil that comes on 2stroke oils.. I saw that there was silicone on the gas cap from the inside with a piece dangling off .. i removed it and washed the tank from the inside with water and let it to dry out.

When I inspected the head gasket a bit closer i noticed the silicone that was put there between the gasket and the head was completely blocking some of the water passages.
View attachment 259470

we cleaned up the cylinder best we could and reassembled the engine with the new gaskets.
View attachment 259475 View attachment 259476 View attachment 259477 View attachment 259478

Now I just need to seal the trim cable hole in the tray, wash the headpipe/pipe since they have a lot of carbon buildup and put everything back in to test it out

To be honest I feel a lot better about the engine/carbs now

I'm so glad you finally decided to take everything apart to clean and inspect. Looks like you had a bunch of little problems adding up. Hopefully it will work better for you now. Make sure you don't cut any corners on the job. Lots of problems there and you don't want to miss anything and have to do it again.

 

[Vumad]

You DO NOT want to run the Stock recommended jetting!! That is for a 100% stock engine. You will want to start with a little richer jetting then what your exhaust pipe manufacture recommends.

Edit: Read back through your thread and see you have a bpipe. Here is the jetting per FPP:

Main Jet: 135 (130 stock)
Pilot Jet: 70 (stock)
High speed screw: 1 2 turns out from closed
Low speed screw: 1 1/4 turns out form closed
Needle & Seat: stock (55 psi)
Spring: 95 gram (You probably have a 115g in there)

I was richer than that and stuck a piston. My stock motor with pipe head etc is 140/75@18psi

 

[LMnsr]

So what should i use then carbwise? Jets and adjustment?

 

[Vumad]

So what should i use then carbwise? Jets and adjustment?

I have a 710 (1mm over bore), 170psi, FPP mod chamber, stock carbs an airbox (2 screens), dual stage fiber reeds (not carbon), reed stuffers, stock ignition, jetworks FCV, 13/17 prop (I think, whatever impros listed for a limited).

My carbs are at 140 main, 75 pilot, 18 psi pop off (I forget the specs, look at the mikuni chart and use the smallest N&S that gives that pop-off). My FCV comes on about 3000RPM. I don't recall where my pipe screws are set, it does not sizzle so it could be adjusted more.

I turn 49mph at 7250 RPM WOT. I know you are not a racing / rec rider so you may want something slightly different. My ski is perfectly crisp for most riding conditions. It will occasionally load up in the surf so I can see how being leaner may be good for some people, but we have really poopty surf in the gulf and I can't ever get it onto pipe. I do not load up in Daytona where the surf is clean.

So, in short, I would start with at least 140/75@18, or maybe even a bit richer, and lean it out from there.

Edit: You are probably going to ask about screw adjustments. They say your low speed screw is only used to set your idle, but I feel it has an effect on the low end. I generally start 1.5 turns out, adjust it on the trailer, then do my pilot jet, then fine tune my low speed screw.

For the high speed screw, I usually start 1.5-2 turns out, then set up my main, then fine tune the top. This adjustment can contribute to a stuck piston, so be careful. If you hold it WOT and it drops RPM at all, immediately stop what you are doing, you are a split second away from a seizure.

In my opinion... Low screw > Pilot > low screw > popoff > main > high screw > go back to previous step if necessary but don't forget leaning the low end leans the middle in the top, so be careful.

 

[LMnsr]

I have a 710 (1mm over bore), 170psi, FPP mod chamber, stock carbs an airbox (2 screens), dual stage fiber reeds (not carbon), reed stuffers, stock ignition, jetworks FCV, 13/17 prop (I think, whatever impros listed for a limited).

My carbs are at 140 main, 75 pilot, 18 psi pop off (I forget the specs, look at the mikuni chart and use the smallest N&S that gives that pop-off). My FCV comes on about 3000RPM. I don't recall where my pipe screws are set, it does not sizzle so it could be adjusted more.

I turn 49mph at 7250 RPM WOT. I know you are not a racing / rec rider so you may want something slightly different. My ski is perfectly crisp for most riding conditions. It will occasionally load up in the surf so I can see how being leaner may be good for some people, but we have really poopty surf in the gulf and I can't ever get it onto pipe. I do not load up in Daytona where the surf is clean.

So, in short, I would start with at least 140/75@18, or maybe even a bit richer, and lean it out from there.

Edit: You are probably going to ask about screw adjustments. They say your low speed screw is only used to set your idle, but I feel it has an effect on the low end. I generally start 1.5 turns out, adjust it on the trailer, then do my pilot jet, then fine tune my low speed screw.

For the high speed screw, I usually start 1.5-2 turns out, then set up my main, then fine tune the top. This adjustment can contribute to a stuck piston, so be careful. If you hold it WOT and it drops RPM at all, immediately stop what you are doing, you are a split second away from a seizure.

In my opinion... Low screw > Pilot > low screw > popoff > main > high screw > go back to previous step if necessary but don't forget leaning the low end leans the middle in the top, so be careful.

Thanks for the reply.. I will have to see where i can find some jets here.. i doubt i will find any but i will try. Let's say i don't luck out and am stuck with the current ones.. Should I try tuning it using those? sry if it's a stupid question but i'm kind of new to jetting.

 

[Harbor]

Glad you took it apart, sounds like you found a bunch of things, good deal Bro!!

 

[Vumad]

Thanks for the reply.. I will have to see where i can find some jets here.. i doubt i will find any but i will try. Let's say i don't luck out and am stuck with the current ones.. Should I try tuning it using those? sry if it's a stupid question but i'm kind of new to jetting.

You can't fudge jet sizes. If you need a 140/75, you can not put a 142/72 in it and have it work right. I know the mikuni manual says the pilot and popoff work together, but a 75@18 is not going to work exactly the same as a 72@25. There are no substitutions for proper jetting.

Start with what you have, then order what you think you need from jetmaniac.

Just be careful it what you have is leaner than what you need. It's always safer to start fat and then go leaner. If you have a similar setup to what I have, I would get 140 and 135 mains and 75 pilots (stock is 130/70). Is also get some 2.0 needles and seat, 65 and 95 gram springs. You can buy the in between sizes later if necessary.

Only buy genuine mikuni parts.

 

[LMnsr]

You can't fudge jet sizes. If you need a 140/75, you can not put a 142/72 in it and have it work right. I know the mikuni manual says the pilot and popoff work together, but a 75@18 is not going to work exactly the same as a 72@25. There are no substitutions for proper jetting.

Start with what you have, then order what you think you need from jetmaniac.

Just be careful it what you have is leaner than what you need. It's always safer to start fat and then go leaner. If you have a similar setup to what I have, I would get 140 and 135 mains and 75 pilots (stock is 130/70). Is also get some 2.0 needles and seat, 65 and 95 gram springs. You can buy the in between sizes later if necessary.

Only buy genuine mikuni parts.

Thanks! i will start with what i have to test it out to make sure the bogging is gone.. I'm going to put the engine in today/tomorrow so i can set the idle on the trailer for now and the rest on saturday or sunday at the beach.
I'm also going to seal up that trim cable hole near the pump, i checked inside the engine bay but it's completely sealed including the scupper. (So i guess i might as well get a second bilge pump or a larger one)
My pole breather holes i managed to seal them off with whatever i could find. hopefully it works. I got thick plastic part's bag that came with the rebuild kit and put a square piece of gasket material from a role i had, sealed off the bag and tightened it between the hull and the pole bracket.
doesn't look great but it's way better than having them basically open..

I will update the post as it comes along...

 

[LMnsr]

I know this thread isn't done but I wanted to thank everyone for the help! I'm still in the learning process but you guys helped me out so much, and I am very grateful for that!