Hard starting, needle/seat

[FinnExplorer]

Hi. I've had to deal with hard starts this season. Gas is smelling and I have to crank long time with throttle wide open to get it to start. Carbs were freshened up with repair kit but if I remember correct, needle valves & seats weren't included in the kit. I believe that is the problem I'm facing here. I've been reading shop manual and parts catalog and I've come to conclusion that I need Mikuni 1.2 Needle Valve (with Viton tip) & Seat SBN Super SBNI Carb x2? And maybe the o-rings for aforementioned. Confirm this as correct you gurus and I can put my credit card to work! :thumbsup:

 

[jhjesse]

Needles and seats are usually sold separately. If you change them make sure to change the o rings, as well.

Not familiar with explorer. Do you have a vent fan? If so, run the vent fan or vent the engine compartment before starting so the carbs can have fresh air.

 

[FinnExplorer]

Yes there is blower fan in Explorer but I remember trying to start with seat/hatch off and it didn't make a difference. I was browsing Ebay and was left in that conclusion that needle valve and seat is sold as a pair like this one for example: http://www.ebay.com/itm/MIKUNI-SBN-..._Watercraft_Parts&hash=item2ec88fe9a4&vxp=mtr
That one even has the o-ring in it doesn't it?

If some of you guys with more knowledge would confirm that I need size 1.2 mm not 1.5 or something else... I found many sizes but starting from 1.5 to lot bigger ones.

 

[Dr Honda]

Gas fumes are heavy... so simply opening the hatch doesn't do anything. So... if you can smell gas... then there isn't any O2 in the bilge. The fan is there for a reason, and it should have a tube hooked to it, going to the bottom of the bilge, to draw up those fumes.

I'm not saying it's not the N/S in the carbs... but my islandia will start/cough/die, or simply won't start, if I'm sitting for 10~15 min, and don't run the bilge fan first.



OK... with that said... when you cleaned the carbs... did you check the pop-off, and verify that the N/S weren't leaking? The reason I'm asking is, the N/S can be fine... but if your high speed check valve is leaking... the carbs will drain when the engine is turned off. This is a 2-fold issue.

1) The engine is lightly flooded, and makes extra fumes in the bilge.

2) The carbs are dry, and have to refill.



As far as your question......


Most of the older seadoo carbs used a 1.2 N/S. If you are buying new... DO NOT buy an aftermarket N/S !!! They aren't always machined right, and can cause other issues. (Not worth trying to save $10)

 

[FinnExplorer]

Yes you might be correct on the fumes, but I may have exaggerated the smell. It's not like I smell it instantly as I open the engine bay. It's more like when you wet the plugs in older cars and it only is there when you start cranking the engine.

Pop-off wasn't tested, because originally the carburetors were working just fine. I just wanted to replace the internal filters and old gaskets. "If it ain't broke, don't fix it" lol
Other than that boat performs like it should.

Thanks for all the info so far!