Idle Air Vent & Main Jets on Sportjet 210 Carburetors

[Michael Dowd]

I went and performed my first water test yesterday and found that the float in the center carburetor was sticking. Returned to the trailer and once back at our garage removed it and found that the Idle Air Vent and Main Jets were different sizes than what the service manual says they should be. With my curiosity heightened I removed the top and bottom carburetors and found that of the (12) total jets only two of them were correct. Some of them were out as much as .010”. I was told by the previous owner that all of the service was performed at a Seadoo repair facility. There was no rhyme or reason to them in relationship to the cylinders they were associated with either. On some locations the air vents were over size with the main under size and visa virus.

My question is does any know if there is a logical reason for someone would have changed them as dramatically as they did from what was recommended by Mercury?

Could this have been a contributing factor to why my original engine failed?

I ordered replacements based on the recommended sizes indicated in the service manual and unless someone has a reason why I should not correct them will be doing it next weekend.

Non-related question, per the manual, the jet sizes for each cylinder differ, can anyone tell me why to satisfy my curiosity.

As always thank you for expertise and guidance.

Mike

 

[Dr Honda]

No idea why they would be different than the manual. I know for a fact that these engines will run properly with the OEM sizes. The only real thing that comes to mind is... the carbs were messed up, and the bought a used set from a different year outboard, and never checked the jetting.

The reason the jets will be different sizes (from factory) can be from a bunch of sources.

1) The crank will twist some at full power, so the actual full throttle timing from the top cyl to the bottom cyl will change by a few degrees. A little extra fuel will keep it cool.

2) The temp of the engine block can very... so here again, a hot piston can benefit from a little extra fuel.

3) Since the engine is tall... known air quality in the bilge can change... so a slightly different tune can help.

Back to your tuning... if that boat was used at higher altitude... the jetting could be different for thin air. OR... if the engine is "Over sized" from a re-manufacture... you may find that it needs a rejet.

 

[Michael Dowd]

Tony,

Thank you for your feed back. It is greatly appreciated. Have all new jets on order based on the information in the service manual. Do not know what if anything will improve but at least I know that they are now what they should be.

 

[Michael Dowd]

Received my replacement jets and re-build kits last week, assembled everything, and did my water test yesterday. Everything went great! Performing the break-in of the new motor as recommended by the manufacturer now and cannot wait to start having fun with it.
Mike

 

[Dr Honda]

great! glad to hear it's working out for you.