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

[LMnsr]

That's what I said 8 posts ago.. I had the same issue with my 650sx with the pisser and found out it was my head gasket. Before diving into the carbs and messing with all that complicated stuff, get yourself a new head gasket and go from there.

Sorry i didn't think of your post after spotting it in the videos... thanks! Ordering one today. hopefully I'll get it this week

 

[LMnsr]

Good find Lmsnr! Bruceski has it, I recall seeing a bunch of rust coming out between your head and cylinder too. That might explain your slightly lower compression in one cylinder

I didn't think it could be a gasket since i bought it as "recently rebuilt" but I think I'll just order a head gasket to test it out plus a complete gasket set, and rebuild the engine to be safe.. I am going to redo my hull anyway so I might as well rebuild the engine while I'm at it

 

[Harbor]

I didn't think it could be a gasket since i bought it as "recently rebuilt" but I think I'll just order a head gasket to test it out plus a complete gasket set, and rebuild the engine to be safe.. I am going to redo my hull anyway so I might as well rebuild the engine while I'm at it

Ya I know what you mean. Didn't seem quite as advertised.

 

[Vumad]

I didn't think it could be a gasket since i bought it as "recently rebuilt" but I think I'll just order a head gasket to test it out plus a complete gasket set, and rebuild the engine to be safe.. I am going to redo my hull anyway so I might as well rebuild the engine while I'm at it

Bills ski had been built, until the rear crank seal half fell out and then harry discovered his seals had been installed backward.

I didn't have time or a clean place to rebuild my motor. I took it to someone that works at a dealer. Tuning was part of the deal. I got the all clear, actually, he handed me the GPS and said to hold it wot as long as you like. Stuck a piston. Then he redid the work free but parts at my expense. This time I checked his work, compression 200+ psi, that would have cost me a second motor, but then I met harry, no problems since.

Recent rebuild means nothing unless there are receipts from someone reputable.

 

[LMnsr]

So I went ahead and removed my head today. My pistons have a pretty hard layer of that black stuff. thinking it's carbon buildup? When I first saw them I felt it in my stomach. Just saw all my repair costs go up.

front cyl
rear cyl

rear head
front head darker
they put silicone between the gasket and head.. I'm pretty sure your not supposed to do that (correct me if im wrong)

 

[BruceSki]

Put a new head gasket on it and I bet it runs much better.


Might want to make sure your jetting is good too. That piston wash doesn't really look correct.

 

[LMnsr]

Put a new head gasket on it and I bet it runs much better.


Might want to make sure your jetting is good too. That piston wash doesn't really look correct.

Thanks. I have a set on the way. Just takes longer for me to get them.
Is it time for new pistons or to have someone overhaul the engine? Since the wash covers the whole piston does that mean i'm running too lean?

Also my carbs need tuning, Was planning on tuning them this weekend, but i'll wait for the new gasket. what would be a good jetting starting point?
I live at sea level and temps here are an avg around 90 degrees and water temps vary from 77-84 about

 

[High Speed Industries]

Does the ski start easier with full throttle or no throttle? When were your carbs last rebuilt? If they were rebuilt recently did you use genuine mikuni parts? Do you know what your current jetting is?

Please list your whole engine setup. Cases, cylinder, head, bore, porting, pipe, carbs, ignition, ect. Who built the engine? Did they use OEM gaskets and seals?

This information might help us point you in the right direction.

 

[Vumad]

You don't need to replace your pistons because of carbon build up. You need to tune your ski.

 

[LMnsr]

Does the ski start easier with full throttle or no throttle? When were your carbs last rebuilt? If they were rebuilt recently did you use genuine mikuni parts? Do you know what your current jetting is?

Please list your whole engine setup. Cases, cylinder, head, bore, porting, pipe, carbs, ignition, ect. Who built the engine? Did they use OEM gaskets and seals?

This information might help us point you in the right direction.

The ski starts with no throttle fine once the gas reaches the carbs.
I bought the ski as a RTR ski about two-three months ago so i'm not sure about anything that has to do with the carbs and parts used, I also have no clue what my jetting is...it stated that it had a fresh top-end with maybe 8 hours on it.. I have been riding basically every wknd sat-sun since I got it except for maybe 2 weekends (most of the time testing to see if problems were solved). It had some other issues like overheating because of a restrictor and the starter was bad and burnt my ground wire. Has a new starter now. I also switched to dual cooling.

The engine is a 62T case with a 61X cylinder bored to 710cc,
GroupK milled head (no idea what option though),
mild porting,
factory B-pipe,
stock 38mm carbs,
stock ignition,
running true dual cooling line setup,
pretty sure Factory Waterbox,
NGK BR8HS plugs,
hood breathers, sealing pole breathers since I am running a UMI pole.

That I can think of, that's it

 

[LMnsr]

You don't need to replace your pistons because of carbon build up. You need to tune your ski.

ok that makes it better ha

 

[High Speed Industries]

Take your carbs apart and see what's inside of them.

 

[Vumad]

The ski starts with no throttle fine once the gas reaches the carbs.
I bought the ski as a RTR ski about two-three months ago so i'm not sure about anything that has to do with the carbs and parts used, I also have no clue what my jetting is...it stated that it had a fresh top-end with maybe 8 hours on it.. I have been riding basically every wknd sat-sun since I got it except for maybe 2 weekends (most of the time testing to see if problems were solved). It had some other issues like overheating because of a restrictor and the starter was bad and burnt my ground wire. Has a new starter now. I also switched to dual cooling.

The engine is a 62T case with a 61X cylinder bored to 710cc,
GroupK milled head (no idea what option though),
mild porting,
factory B-pipe,
stock 38mm carbs,
stock ignition,
running true dual cooling line setup,
pretty sure Factory Waterbox,
NGK BR8HS plugs,
hood breathers, sealing pole breathers since I am running a UMI pole.

That I can think of, that's it

Was it your post that I replied to the other day about redoing your tray because the ski sank?

I think you need to disassble everything, do a leak down test on the motor and visually inspect everything else. If motor fails leak down, take it all the way apart.

You can do a ghetto test of your crank rod bearings by going past tdc, so crank and pistons are on down stroke. Hold The coupler on the crank and push down on the piston. It should not move. No way to check main bearings without tear down.

 

[LMnsr]

Was it your post that I replied to the other day about redoing your tray because the ski sank?

I think you need to disassble everything, do a leak down test on the motor and visually inspect everything else. If motor fails leak down, take it all the way apart.

You can do a ghetto test of your crank rod bearings by going past tdc, so crank and pistons are on down stroke. Hold The coupler on the crank and push down on the piston. It should not move. No way to check main bearings without tear down.

Yes that was me.. but the ski didn't sink all the way only half of it did but the rear end was underwater and about half the engine bay on top. But the bogging issue was here way before that happened last wknd. I rode the ski when it started after the bildgepump cleared the water and everything seemed fine.

I think I might just have someone rebuild the engine once I receive the engine gasket set. I have a set of head gaskets on the way so I can see if that was the issue and tune the carbs. Then once that is done it's rebuild time. I will service my carbs before i test out the head gasket though

 

[LMnsr]

Take your carbs apart and see what's inside of them.

I will do that today or tomorrow. as soon as i see what's inside i'll let you know

 

[LMnsr]

One of my carbs is stuck to one of the threads and will not come off. I tried tapping it with a hammer. Pulled from the top with all my force. I feel the front one loose but the rear is being a pain.

 

[LMnsr]

I'm giving up on this today. Seems like every small thing I have to do on this ski becomes a bigger job.
I'm even starting to regret buying this particular ski.
I probably will let the ski sit there until I can buy an engine that's in better condition. All i have been doing is fixing issues with this one.

 

[LMnsr]

Thanks everyone for all the replies, and hopefully this will help someone else.. At the moment I'm done with this engine

 

[High Speed Industries]

Use some penetrating oil on that carb and try to knock it loose by gently tapping it with a rubber mallet. I can imagine you can get it off easily. Don't give up just yet, I'm sure you will get it.

 

[Vumad]

Yes that was me.. but the ski didn't sink all the way only half of it did but the rear end was underwater and about half the engine bay on top. But the bogging issue was here way before that happened last wknd. I rode the ski when it started after the bildgepump cleared the water and everything seemed fine.

I think I might just have someone rebuild the engine once I receive the engine gasket set. I have a set of head gaskets on the way so I can see if that was the issue and tune the carbs. Then once that is done it's rebuild time. I will service my carbs before i test out the head gasket though

I'm not saying to take it apart because it sunk. I'm saying to take it apart because it has a laundry list of issues. Fix them all and be done with it.

I'm giving up on this today. Seems like every small thing I have to do on this ski becomes a bigger job.
I'm even starting to regret buying this particular ski.
I probably will let the ski sit there until I can buy an engine that's in better condition. All i have been doing is fixing issues with this one.

So exactly my point. Take it all apart. Fix everything. Too many shortcuts were made by the previous owner, or it's just worn out, either way, be preemptive.