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92 gtx needle valve and seat ?????

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ape1972

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Hi everybody!

I have a 92 GTX and I believe it needs new needle valves and seats. it is completely original with no mods! Could someone please tell me what type I should get.

Thanks, Adrian
 
Get Genuine MIKUNI carb kits and seats. Or just the needle and seats (they come separate)

I would go ahead and replace the gaskets in the carb as they are 23 years old..

But if you're on a budget, and the diaphrams are still soft, you could squeak by with just the N&S kits.

BTW what makes you beleive you have bad needles and seats?
 
Thanks for the quick reply!

I'll try to make a long story short! I purchased this GTX about a month ago. The previous owner told me it needed a new MPEM so I replaced the entire box. It ran but not very good! I checked all full lines (black rubber) and fixed the pickup lines in the tank. It runs when it wants to! When it does run the idle is very low.. to the point of stalling. It will not always restart either.

If you have any insight it would be greatly appreciated.

Thanks, Adrian
 
First off, what is the compression? Should be around 150 psi. anything below 125 psi and its time for rebuild.

As for the the idle, is this being tested in the water? When it dies, do you have to give it full throttle to start and does it cough and sputter to life? If so, then it may just be rich and need a low speed carb adjustment. What do your plugs look like? are they black and wet?

If you shut the ski off and wait 2 minutes, then go to start it and its hard starting, again needing throttle, then I would suspect the needles and seats. You can verify that by a Pop-off test. Search on youtube and you can build your own for cheap from a hardware store.
 
The compression is around 100 psi!
I am testing it out of the water with the flush kit. It will start without giving it any throttle but sometimes I have to give it a little. It does not cough and sputter to life. It's strange because sometimes it fires right up with no problem but sometimes it takes a while. The spark plugs are dark and wet! As for after two minutes, sometimes it does start sometimes it does not.

Thanks again for all your help, Adrian
 
The compression is around 100 psi!

Well if the engine is at 100psi.. there's nothing that tinkering with the carbs will do. Take the compression test again, with a teaspoon of oil in each cylinder, throttle wide open, and crank until the gauge peaks out.

Low compression will make the plugs look wet and fouled, as there isn't enough compression for complete combustion
 
Ok! I will check the compression again! The compression gage that I have is from harbor freight is unreliable. It gave me two different readings so i'll have to get another one.

Another question!!!

I removed the flame arrestor and it ran pretty good for a while. I shut it off and waited and it fired right up. I repeated this a number of times and same results. No bogging down, sputtering, stalling. etc. It still had a low idle though.

Oh! I had black sludge coming out the exhaust! Could that be from low compression?

Thanks, Adrian
 
Yes, I would get another gauge first. Be sure to test each cylinder 3 times, take the one thats in the middle.

The low idle,could be corrected with turning up the idle screw. Does the engine buck and run rough at idle or is it smooth, but low?

And yes the black sludge can be caused by low compression, too much oil, or a combination of both.

Does the ski smoke excessively?
 
The engine does run a little rough at low idle but the idle is low almost to the point of stalling. If I use the throttle to raise the idle it is pretty smooth. The ski does not smoke excessively. If it finally starts after several tries it may smoke at first but then leans out to normal.

I also noticed that when I start the ski cold, the idle is normal then drops off to very low after it has ran for a minute

Thanks, Adrian
 
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Today I decided to do some more troubleshooting and here's what I found.. Since I purchased another electrical box I didn't think the problem was electrical till now. Just out of curiosity I took out the spark plug to check if it was sparking and it was not! I disconnected then reconnected the off switch than it had a spark.

Could anybody tell me where to start my process of elimination.

Thanks, Adrian
 
Well that would cause some problems. First, try taking the spark plug boots off and try clipping 1/4 inch of the wire off and re-attaching. Sometimes you get corrosion in there and you get a bad connection. Next, get some new, or gently used plugs. The fouled plugs may be missleading you.

And check the compression again and report back. There is no point digging deeper if your engine is worn out.
 
I checked the compression with a new gage and it's 130 psi on both sides. I did this test with no added oil. I purchased new spark plugs and will clip the wires about 1/4 inch.
 
Well you may be lucky and be able to squeeze another year or two out of that engine. rebuild time is 125 psi, so keep that in mind if you notice it doesn't have that much power.

Another really good investment is a spark checker. They are like 5 bucks at the autostore. You can put it inline and check each cylinder if its firing consistantly or not. I dont recommend checking for spark with plugs anymore... sometime last year someone posted they did that and the spark actually ignited gas vapours and blew up his ski, and put him in the hospital.
 
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