I am working on fixing a hard start when hot issue and fount my rotary valve clearance was at .016, max spec is .014 on my 1997 GTX. There were some marks on the valve and cover so I decided to order a new parts. I am using the OSD marine rotary valve that is .024 thick which is .001 more than my old one so I think that is ok. I am getting .019 of clearance with the machined cover from SBT now. Has anyone had issues with their covers not being machined correctly?
Rotary valve clearance worse with SBT reman cover, .019?
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Do you have a way to measure the the different depths of the machined surfaces?? I machines these. If I remember correctly I go for .103" from the rotary valve surface to the mounting surface. If you are using solder that is too think you can get a false reading because it won't compress enough. I purchased .032" solder. .062" is a lot more to crush. You can try cutting the solder in half and taking another reading. Is the gasket in place when you are measuring?? Make sure the surface is clean, no burrs or distortions. At which points are you measuring? don't measure close to the ports.
I don't think you'll have trouble with .019 and I know you won't have trouble with .016". If you have trouble with a hot start check your compression also.
I don't think you'll have trouble with .019 and I know you won't have trouble with .016". If you have trouble with a hot start check your compression also.
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I have the o-ring out and my solder is measuring .040 before crushing and i am using torque wrench on bolts. Measuring at top and bottom, not close to the holes. Last spring both cyls were approx 150, maybe put 2 hours on ski last season due to starting issues. I will recheck compression when I put it back together again. I will measure the distance from the 2 surfaces tomorow if weather permits.
I called SBT today and the tech line said they machine the covers to .100 from the face to the flange. I measured the cover sent to me from them and it is at .100 but I checked it again and am still getting .019 on the clearance. From the other post I have read I really need to have my clearance lower. Does anyone know what the factory machines the covers to from the flange to the face. I don't know if its possible to get my old cover back from them but may try, any thoughts on this?
If you know the machined surface is at (.100") and your valve is (.024") just measure the depth from the gasket surface and you'll have the clearance numbers. I thinking about (140") maybe as I am going from memory and the sizes I have done. My last one I might have done (.105") I like to be in the middle of the range.
Measure everything and do the math.
Measure everything and do the math.
The SBT cover is .100". Your valve plate is .025" That's .0125" I think the depth of the recess on the engine casing is around .140" you'll have to measure that to verify. If those are the numbers your clearance is .015"
If the solder you are using is not compressing enough you are getting a false reading. the solder should be cut about 1/2" long. As a note, I don't torque the cover. Make sure your bolts are screwing all the way in and not bottoming out and you have no deformaties, material, or debris on the sealing surface.
If I were machining these plates for mass production. I'd bet at .103" and even that puts you at the top of the clearance range. I can say that more clearance is better than less. More doesn't hurt much, less can do damage. I lean more to this being a non-issue and I'm not sure SBT is gonna do a special order for an individual. Good Luck.
If the solder you are using is not compressing enough you are getting a false reading. the solder should be cut about 1/2" long. As a note, I don't torque the cover. Make sure your bolts are screwing all the way in and not bottoming out and you have no deformaties, material, or debris on the sealing surface.
If I were machining these plates for mass production. I'd bet at .103" and even that puts you at the top of the clearance range. I can say that more clearance is better than less. More doesn't hurt much, less can do damage. I lean more to this being a non-issue and I'm not sure SBT is gonna do a special order for an individual. Good Luck.
Hard start I'd look for a fuel restriction, pump problem. Pull a vacuum on the fuel system by clamping the lines near the baffle. Check both "reserve" and "on"systems. If you have an inline filter on that ski remove it. Lots of times there is a leak at the water separator gasket. Hot starting can be compression. Take a new compression reading. Engines degrade quickly when they have a problem. You may have low compression on one cylinder. Good Luck.
I got a more accurate caliper to measure everything today,
0.100 on the cover + 0.023 for the valve = 0.123. Case gap was 0.136 - 0.123 = 0.013.
Much happier with that, Etemplet THANKS for helping me through that.
As for the fuel system I will try to check it tomorrow while I have the carbs are off and fuel lines are disconnected.
Just replaced the fuel pump check valves while I was double checking all carb settings, pop off 32 psi and held pressure also, rebuilt last year with Mikuni kits from OSD.
No inline fuel filter in the system and I just replaced the separator gasket half way through last year.
I am going to do a compression test tomorrow, will it make a difference with the carbs off?
0.100 on the cover + 0.023 for the valve = 0.123. Case gap was 0.136 - 0.123 = 0.013.
Much happier with that, Etemplet THANKS for helping me through that.
As for the fuel system I will try to check it tomorrow while I have the carbs are off and fuel lines are disconnected.
Just replaced the fuel pump check valves while I was double checking all carb settings, pop off 32 psi and held pressure also, rebuilt last year with Mikuni kits from OSD.
No inline fuel filter in the system and I just replaced the separator gasket half way through last year.
I am going to do a compression test tomorrow, will it make a difference with the carbs off?
I use a Mitey-Vac pump but I bought one that doesVacuum and Pressure off Ebay. Works great. I pulled a vacuum to check for leaks. Then I I have a leak I use pressure to find them.
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