9.9 hp Slow Speed Needle VERY HARD to Turn

[scout-j-m]

Just bought a nice 1992 9.9 hp last night. I checked compression (110 psi) when I bought it and we ran it on muffs. When I got home I put it on my stand and tested it in a tank. It runs great but I would like it to idle down a little lower. I tried to adjust the slow speed needle but the knob was slipping on the needle. I have a couple other knobs which slipped as well. I began turning it with some pliers but was worried that would create too much torque and I may accidentally seat it in too hard when I screwed it in all the way. The previous owner said his mechanic rebuilt the carb very recently so I imagine it has a brand new bushing to hold the needle in position and protect from vibrations. I have a 1982 15 hp I recently rebuilt and noticed the new bushing on it made it hard to turn as well, however, I had no problems with it being so hard the knob would slip. Is this typical for this series of motors or maybe these later carbs with the plastic top like this one? After a new bushing is installed, should the needle be installed and removed multiple times to help loose it up a little? I like the fact I know it wont move on its own while running but I still need to get it set correctly somehow.

 

[flyingscott]

That needle has nothing to do with idle speed so probably leave it where it is. It goes into a plastic cover that if you wreck that is pricey. Look on the end of the tiller and try loosening the knob there see if that does it. Otherwise there might be a screw under the flywheel for it.

 

[scout-j-m]

That needle has nothing to do with idle speed so probably leave it where it is. It goes into a plastic cover that if you wreck that is pricey. Look on the end of the tiller and try loosening the knob there see if that does it.

Sorry, I wasn't very clear....What I meant is that I couldn't get it to idle down as low as it should without stalling out. I have the idle speed adjustment on the tiller backed off all the way so I could adjust the throttle down as I leaned out the slow speed mixture knob to try to get a nice, smooth, low idle, but like I mentioned the slow speed needle is virtually stuck in place with the use of pliers.

 

[flyingscott]

It should be easy to turn but they are also easy to strip out and jam up in the cover which is what sounds like what happend to yours. You may have to replace the cover and they are about $125 just for the top cover. Up to you if you want to take a chance on it.

 

[scout-j-m]

It should be easy to turn but they are also easy to strip out and jam up in the cover which is what sounds like what happend to yours. You may have to replace the cover and they are about $125 just for the top cover. Up to you if you want to take a chance on it.

Ok, I didn't realize that. I will remove the carb and inspect it better to see what the bind is.

 

[oldboat1]

It sounds like the needle might be cross threaded. I'm not sure the slide-on plastic knob would slip, though, unless the knob was stripped up where it grips the needle(?)

 

[scout-j-m]

It sounds like the needle might be cross threaded. I'm not sure the slide-on plastic knob would slip, though, unless the knob was stripped up where it grips the needle(?)

That was my initial thinking as well. I guess the knob may just be partially stripped but I do know it works on the needle of my other motor. Either way I will pull it and inspect it. This motor is new to me plus it was said to have a 15 hp carb on it which I would like to verify is accurate; will check the float level setting and cleanliness while I am at it too.

And if the plastic top is stripped, maybe I will luck out and have the version with the cheaper top. The parts diagram lists two versions, one of which is as expensive as flyingscott mentions and the other is less than $20.

 

[gm280]

If you remove the tight needle and see any signs it did cross thread, you could use a tap and recut the threads back first before replacing anything. And if you can't find a tap of that fine thread, ue a steel bolt/screw of the correct thread with a Dremel cut in a couple places lengthwise to make your own tap. JMHO!

 

[oldboat1]

^^^good tip. As another variation, you might try thickened epoxy to rethread (a little MarineTex, maybe). Wrap the needle in some plastic wrap and spread some epoxy on it. While the epoxy is setting up, thread the needle into the housing, and back it in and out a little. Work up toward the front of the carb, but leaving room for the little retainer -- object is to keep the needle in place and stable, with the point seated in the little orifice.

 

[scout-j-m]

Thanks guys. I pulled the carb earlier along with the plastic top. Even with the plastic piece removed it was hard to unscrew the needle. I held the needle with pliers and untwisted the plastic cover. I then removed the bushing and threaded the needle back in....with no problem thankfully. The threads felt smooth. I then removed the needle and threaded it in and out of the bushing several times to see if that would help soften it up or cut threads in it better. And then I dabbed on some 2 stroke oil on the threads and reassembled. It went in easier but still hard. I found a second knob which worked better but still slips more than it grabs. I think the actual end of the needle is stripped a little. Anyways, I set it to 1 1/2 turns from best I could tell was lightly seated with pliers.

I went ahead and pulled the bowl and the float was set correct and it was very clean inside. Put it back together and reinstalled the carb and did a quick link and sync. It still had trouble idle down low smoothly and again I wasn't able to adjust the needle with the knob. But I have still yet to check spark so it may have a weak cylinder. Called it quits for the night when the recoil starter for some reason quit winding back in.

Now back inside I'm looking at some pics I took of the part numbers. Google in the plastic pieces part number, it is showing up as being for a 1993 model. That is when they made changes to this 9.9/15 series so I'm not sure if this piece will work or not. The screw with RTV looking stuff around it isn't even present on the 1992 plastic piece from the pictures I looked at online. Looking at the carb body I see 384051 and MX431824, neither of which I have been able to find online to see what year the carb body may be although I'm leaning towards it being a 1992 from some unverified search results.

 

[scout-j-m]

Just realized this is in fact a 1993 top and that the screw with rtv is where the slow speed needle actually goes. Where the needle is now it looks like a screw plug goes. I'm assuming the backwardsness is really screwing up the idle mixture.

 

[oldboat1]

Thinking rebuilding (essentially replacing) the top end might be workable: http://www.iboats.com/Carburetor/dm/cart_id.152058277--session_id.379433631--view_id.1547033 ('93 shown). Actually, sounds like it runs remarkably well for what it is.

 

[scout-j-m]

Thinking rebuilding (essentially replacing) the top end might be workable: http://www.iboats.com/Carburetor/dm/...iew_id.1547033 ('93 shown). Actually, sounds like it runs remarkably well for what it is.

As in buy part numbers 2, 15, 14, 17, and 11 and make the 1993 plastic top work?

 

[scout-j-m]

Thinking rebuilding (essentially replacing) the top end might be workable: http://www.iboats.com/Carburetor/dm/*******.152058277--**********.379433631--view_id.1547033 ('93 shown). Actually, sounds like it runs remarkably well for what it is.

It actually does run well considering. Runs great at slightly higher speeds and idles better than I would expect considering it is probably running extra rich or lean with the way it is right now.

 

[gm280]

Not absolutely sure, but that looks remarkably like my, now passed on, neighbor's old engine carb and plastic top. Be very careful with it because he broke his and the replacement was listed well over a hundred dollars. It is more like the old Bakelite material used years ago. But it too is breakable and not as pliable as other plastics. JMHO!

 

[scout-j-m]

I'm torn what to do as of now. I can order the correct plastic cover for a 1992 carb for about $15. I'm not sure if my current needle is the correct one or not though and a new one for the 1992 cover is $30-40. According to Leroy's Ramblings these plastic topped carbs have different length needles than the old metal ones and who knows which one I have.

Other option is to get the needed parts for the 1993 top which I appear to currently have. The needle and spring for it run about $25 and the seal and plug that go where the low speed needle is currently inserted total about $10.

 

[oldboat1]

As in buy part numbers 2, 15, 14, 17, and 11 and make the 1993 plastic top work?

Yes -- looks like it could be reconstructed pretty reasonably.

 

[scout-j-m]

Yes -- looks like it could be reconstructed pretty reasonably.

I think I will take your advice and go that route since it will be slightly cheaper.

 

[oldboat1]

Think it's got a chance.

 

[scout-j-m]

I got the new parts in and installed them on the plastic top yesterday. I had to ream out the slow speed needle threads a little though because the screw that was out in there to plug it was much coarser thread than the needle and it wouldn't have gone in otherwise. I set it to 1 & 1/2 turns out and it seems like the motor is running better but was hard to tell because I just used muffs. Later this afternoon I am going to give it a lake test, however, there are two current issues still. First being that the metal piece that attaches to the top of the carb and that holds the choke lever interferes with the slow speed needle enough that I will have to leave it removed to adjust the needle. And second, the carb is dripping fuel from the bowl. I can't tell if the it is coming from a crack in the bowl, the bowl gasket, or another place. It's not a big deal at this time but it is dripping enough that the lower cowl has a puddle of fuel which is running down near the powerhead gasket and down the leg of the motor.

I'll report back with the results and if all is well move on to fixing the leak or replacing the entire carb with my 1982 model 15hp one.