9.8 nissan slow jet

[pajet]

use 9.8 4 stroke only for trolling have to dissasemble and clean carb yearly.this time i removed slow speed jet ohoh screwed back in to bottom will not idle properly should jet not been screwed all the way in? if not is it ruined?thanks

 

[pvanv]

Re: 9.8 nissan slow jet

What model 9.8 are you working on?

If you're talking about the NS9.8A, are you also talking about the idle mixture screw (up high on the outboard/starboard side of the carb)? If so, did you drill out the brass EPA plug to get access to it?

If that's the screw in question, it is not supposed to be all the way in. The specific adjustment will be somewhere around two turns out, but each motor/carb setup needs to be tweaked for the exact correct idle mixture. Do NOT ram the screw in all the way, as the tip is very small and delicate. Lightly seat it, back out 2 turns, start and warm up the motor, then idle slowly, and adjust for reliable mixture (best slow idle RPM). If you jammed the screw in too tight, you may have damaged the tip of the screw, or the tiny brass jet in the carb body. If so, you will probably have trouble finding parts, and will likely need a new carb.

 

[pajet]

Re: 9.8 nissan slow jet

thanks for reply im talking about the jet inside the float bowl under the brass screw

 

[pajet]

Re: 9.8 nissan slow jet

re,removed and disasembled carb am giving a long soak. the jet that i mentioned is next to the emulsion tube. on closer inspection it appears to screw all the way in. flat on bottom. did not mess with slow mixture screw.

 

[pvanv]

Re: 9.8 nissan slow jet

pajet,

That's the main jet, and yes, it should bottom all the way in. You likely have some varnish crud elsewhere -- maybe in the emulsion tube, which might be cured by a good soaking.

 

[pajet]

Re: 9.8 nissan slow jet

put carb back togeather today after cleaning out the holes in the main jet and emulsion tube with a pin. you could not see through them when held to a light even after a day of soaking. idles and slow trolls perfectly thanks for input. any advice on good parts supplier for this motor?

 

[pvanv]

Re: 9.8 nissan slow jet

Glad it worked out for you. Sounds like you were running poor quality fuel, and it wasn't drained out when the motor sat in storage.

Be careful using hard probes/wire/etc. to clear passages; the tube and jet are (relatively) soft brass, and can be easily distorted. We always do a soaking, followed by a blow-out, and have a good success record.

Being a dealer, of course, my recommendation for parts is to stick with a dealer -- Johnson dealer for Johnson parts, Chevrolet dealer for Chevy parts, Nissan dealer for Nissan parts, etc. Many aftermarket bits are good, but some are not up to spec.

 

[pajet]

Re: 9.8 nissan slow jet

do not think its fuel quality so much as motor is very seldom run at anything above trolling speed. use stabil in all gas. no big deal to clean carb one or two times a year.