1994 SPX issues

[shanejudge]

I have a 1994 SPX. Recently replaced the head o-rings due to low compression. I rebuilt the carbs, replaced the needle valve, seat and springs. New plugs with spark. I’ve got the black springs in there currently, but have the dull and shiny silver springs in a drawer. Pop off pressure is within specs with dull silver and black springs. With the dull silver the ski didn’t want to run, but when it does it idles around 4500-4700rpms. The black springs it runs around 1400rpms until dropped in the water. I’ve read 3000rpms is where it should run sitting on the trailer. Any ideas on what it could be?

 

[etemplet]

Seems like it is lean with the dull silver spring. With the black springs it is more where you need to be with your settings.

Have you tried adjusting the idle or the low speed adjusters? For me, I use the recommended parts and rarely have issues with the carbs. They should work fine with the recommended part and stock settings. Higher pop-off is lean, lower pop-off range is rich. If you use the stock parts the carb should be in the sweet spot.

 

[shanejudge]

Seems like it is lean with the dull silver spring. With the black springs it is more where you need to be with your settings.

Have you tried adjusting the idle or the low speed adjusters? For me, I use the recommended parts and rarely have issues with the carbs. They should work fine with the recommended part and stock settings. Higher pop-off is lean, lower pop-off range is rich. If you use the stock parts the carb should be in the sweet spot.

I assume you’re talking about the adjustment of the throttle cable right at the carbs? I’ve adjusted that, I don’t see an idle adjustment like on my 98 gsx limited. I either get about 1400rpms or I get wide open throttle. I will try the low speed again, but I have it set to 1 and 1/2 out is what is recommended I believe. Everything is stock as far as I’m aware, genuine mikuni rebuild kit to include the needle valve. Thank you for the input, if it works I will reply back

 

[etemplet]

The carbs have an idle adjuster in addition to low and high speed adjusters.

 

[shanejudge]

The carbs have an idle adjuster in addition to low and high speed adjusters.

Is that the double nut right where the throttle cable meets the carbs?

 

[etemplet]

Do you have single carb are double? It will be a screw with a spring that touches the throttle assembly and it opens the butterfly inside the carb. That is your idle adjustment. Circled in the picture. Your carbs make look different but the function is the same.

 

[shanejudge]

Do you have single carb are double? It will be a screw with a spring that touches the throttle assembly and it opens the butterfly inside the carb. That is your idle adjustment. Circled in the picture. Your carbs make look different but the function is the same.

View attachment 58266

I will double check, but I don’t believe it has that adjustment screw. Thank you for the input!

 

[etemplet]

I will double check, but I don’t believe it has that adjustment screw. Thank you for the input!

Might be missing but you need one.

 

[mikidymac]

They all have an idle screw.....

 

[fatblockabody]

They all have an idle screw.....

Yup.


OP, if you don't see one it is likely missing

 

[shanejudge]

So I found the idle screw, got the throttle cable set to a slight resistance on the cable. I’ve got the low speed set to 3/4 turn on both carbs. I’m having idle issues still. It fired and ran in and out of the water for a bit, but as soon as I adjusted the idle it dies and doesn’t want to start again for a few minutes. Any ideas?

 

[shanejudge]

So I have the throttle cable set to have slight tension and just moves when I press the throttle. Low speed screws are about 1 full turn from tight and the idle is set to about 3,000rpms. It runs perfect for a few minutes then it idles up hard and doesn’t idle back down. Any ideas what may cause this? Pop off is right, fuel doesn’t seem to flow different. The air box is on and tight, I’m stumped

 

[mikidymac]

There should be no tension on the throttle cable. You should have a few mm of play at the lever before the cable does anything.

If the idle goes up on it's own and rev's really high that is a runaway caused by a lean condition. Air is getting in downstream of the throttle butterfly.

 

[shanejudge]

There should be no tension on the throttle cable. You should have a few mm of play at the lever before the cable does anything.

If the idle goes up on it's own and rev's really high that is a runaway caused by a lean condition. Air is getting in downstream of the throttle butterfly.

I will adjust the throttle cable to have some play. The gaskets are new, what else should I be looking for? Any ideas? Thanks for the input. Im anxious to get this one in the water and see how she runs!