Carb with no mixture screws??

[BBird]

Working on a pair of 2004 GTI skis, and was going through both carbs to rebuild them. The first one went as usual and runs superb. Went to do the second one and it is a 40mm with accelerator pump, but it doesn’t have any mixture screws (Lo or Hi.) I included a picture for clarity. Just wondering what this might have come off of, and if it will work, or should I just get a new carb that is the correct one?

 

[POPPS]

Wow,,,I find it ”nearly” I,possible for the carb to not hav hi and low mixture screws,,,unless it is a “small engine” from California.

 

[BBird]

I said the same thing, which is why I figured I would ask folks here.

 

[awdunn]

The carb indeed has both HI and LOW adjustment screws - UNDER brass slug plugs.
In the past, at different times, I purchased [2] carbs for my 97 GTI's [717 engine]. Both had caps over the hi and low screws - presumeabley to prevent maladjustments of "correctly pre-adjusted" screws. On mine, the "cap" is a 3/16" thick brass slug. I drilled one out to investigate - see pic, showing brass plug [drilled out] and recessed screw underneath. In this case, it was the hi-speed jet, which for my boat called to be set at "0" [fully closed] - and the screw itself indeed was set fully closed per spec.
Unfortuneately, this "protection" makes it impossible to remove adjustment screws for inspection or cleaning, unless one drills out the slug [which could be problematic].
Some other carbs / configs cover the screws with a plastic cap that limits adjustment of the screw to about 1/8 turn in or out of spec. On those, just pull the plastic cap off the screw to reveal the screw/slot.

 

[mikidymac]

It’s the California model that has tamper resistant carbs.

You can’t get the carbs clean without removing the screws but once you remove the caps they won’t seal and it will never run correctly. Ask me how I know. Battled it for two seasons.

The screws are not the same as any other Mikuni carb and even trying to epoxy them back up didn’t work.

The best fix and money I spent on my 04’ GTI was a brand new carb from OSD with standard high and low screws.

 

[BBird]

Figured it was something like that, and if anybody knew @mikidymac would! Will just get a new one from OSD. The last one I got obviously worked like new, and was very reasonable cost.

 

[POPPS]

Amazing,,,my sincereist apologies,,,on my small engines they come capped,,,but never in a hundred years could I imagine capped screws for a pwc.

 

[BBird]

It gets better…both of the skis I’m working on had the same carb. Maybe there will be an eBay market for them…

 

[BBird]

Looking at info on SeaDoo source.com this could be an issue for folks from 2003-2005 on GTI and GTI LE skis. Based on the part number for the stock carb. I attached a screenshot for reference. Another example of the how the resources on this forum are incredible!

 

[Poormanracing]

Drill it out and put regular low and high speed screws in it just make sure you have orings on them when you install them

 

[mikidymac]

Drill it out and put regular low and high speed screws in it just make sure you have orings on them when you install them

This does not work because the threads in the carb are different than all other Mikuni carb screws. I tried it on mine.

 

[Poormanracing]

I used part number 404162049 and 270500115.they list the parts with the brass plug on parts fiche

 

[JC-SUPERJET]

Are the Adjustment Needle Cone Tip tapers the same as the Original ones?

If they are different, say Original is longer or shorter than the replacement, then the flow in the Low and High Speed Circuits will be different.

Needle Valves with different Tapers have different flows; in between fully Closed and 3 turns out, obviously.

Thus will require different Low and High Speed Adjustment Screw settings...

 

[Poormanracing]

The numbers I listed are from se doo parts house but I remember back at the stealer having the air screws in stock.to the naked eye they looked j7st like the gp 800 and 1200s that had brass slugs.but I never had a running problem after drilling the brass out.there is a oring small washer and a spring keeping the oring sealed

 

[mikidymac]

They are not the same taper or threads. You can't use any of the aftermarket T-handle style. While mine looked fine and trying everything to seal them the carb was just never correct and I have been through tons of these carbs in 30 years.

I finally admitted defeat and bought a new non-sealed carb and it has worked flawlessly ever since.

 

[Poormanracing]

They are not the same taper or threads. You can't use any of the aftermarket T-handle style. While mine looked fine and trying everything to seal them the carb was just never correct and I have been through tons of these carbs in 30 years.

I finally admitted defeat and bought a new non-sealed carb and it has worked flawlessly ever since.

Yes I get that point but sea doo has the part numbers for the Cali set up including a replacement brass plug.