spark plug chop,,,what to do...need quick answer

[Nick_R_23]

This is the spark plug out of my 1985 200S, everythings stock, carb settings are, air mixture screw 2 1/4 turns out, and needle is at middle clip. It seems to run ok, but kinda dies out on top end, and cuts out a bit 3/4-WOT.

Heres the sparkplug after a ride:

http://i84.photobucket.com/albums/k28/Nick_R_23/MVC-003F-17.jpg

http://i84.photobucket.com/albums/k28/Nick_R_23/MVC-004F-17.jpg

The edges are black and sooty, and the ceramic has a slight ash color, and the tip is a light grey.

Sooooo....what needs to happen to the carb?

-Nick :TrikesOwn

[Ryan.]

looks to be running a bit hot

[SWIGIN]

jump up the main a bit

[night4creeper]

Yes, richen up the main jet a little. you could try raising the needle first, but it probably won't give you enough.

[Billy Golightly]

richen the main one, possible 2 sizes and richen the needle one notch would be my estimate judging from that plug.

[Billy Golightly]

P.S. your pilot and idle screw are a little bit in the rich side (don't mess with them though, their plenty good enough, I'm just explaining) because the bottom of the plug, the circle that goes around the ground strap and the porcelain is still pretty dark and in my experience that area is an indicator of low RPM carbeuration.

[Nick_R_23]

P.S. your pilot and idle screw are a little bit in the rich side (don't mess with them though, their plenty good enough, I'm just explaining)

Thats might be hard to do, because the pilot screw fell out of the !@$#ing carb on a ride today, 30 miles from home no less....:mad: When I find another one Ill set it back the way it was and then raise the needle and see how it goes, then buy some larger jets if its still not rich enough.

-Nick :TrikesOwn

[ceaserthethird]

O Shhhhh the pilot jet fell out .... dam

[Nick_R_23]

Ok I found another pilot screw and set it back the way it was before. I took apart another carb I had and they are different then the ones that were in the 200s carb. The larger jet (main jet im guessing) with the screw on cap, the cap is 100, and the smaller jet is 35. On this spare carb I took apart, the cap is 92, and the smaller jet is 38. If Ive heard right, the smaller the # on the jet, the larger size the jet is? So I would want to use these other jets then?

http://i84.photobucket.com/albums/k28/Nick_R_23/MVC-005F-18.jpg

-Nick :TrikesOwn

[Billy Golightly]

On the normal Keihins I'm use to workin with the larger the jet size, the larger the orifice. The 100 should be larger then the 92, and the 38 larger then the 35. I'm a little confused, which jets were you already running?

[Nick_R_23]

The ones that have been in the 200s carb are the #100 and #35. I took another carb apart and found the #92 and #38.


On the normal Keihins I'm use to workin with the larger the jet size, the larger the orifice.

I think you are right, I can look down the #35 and #38 and see that the hole in the #38 is larger.

-Nick :TrikesOwn

[Billy Golightly]

Then you'll probably need a 102 or 105 main jet if you were running a 100 and the plug looks like that would be my estimate.

[Nick_R_23]

Ok, Ill look into getting a larger one. Also, should I still drop a clip on the needle, and should I run the #35 or #38 jet, since Ill be moving to a larger main? Thanks

-Nick :TrikesOwn

[McDerry]

The carbon fouling on the outside of the plug is from oil being burnt at low rpm. Plug itself looks descent, possibly a little lean on wide open, but no signs of glazing on the plug where its melting porcelain. I'd probably keep running that mixture, maybe raise the needle one position. The timing looks half way descent (can tell by the discoloration and location on the grounding strap), could probably be advanced a tad more to help with the top end. Also the heat range of the plug is descent, you have 2 full threads on the outer edge discolored which tends to be a good amount of heat transfer to the outer body of the plug.

[Nick_R_23]

Ok...this is what its at right now. I couldnt get to the shop to get another jet, so it still has the #100 and #35 in there. I moved the clip on the needle from middle position to second from the bottom, and pilot screw is at 2 1/2 turns out. It starts right up and runs ok, but idle is still sketchy, and it tends to stay revved up for a bit when you let go of the throttle.

-Nick :TrikesOwn

[DIGGER DOG]

I dont actually know the specs for the fuel air screw, but the 2and 1/2 setting is really just a starting point you might have to do an idle drop procedure.
to do it right as per Honda youll need a tach and a fuel air screw adj. tool but I have found that the 2and 1/2 adj works fine for most carbs.
There is a jacket that the jet needle slides into under the main jet emulsion tube
check it for dents and what not that may be your problem with the idle and revving up then down.
I wont go into the idle drop procedure as it is rather lengthy If you have a manual
It will explain it

[Rustytinhorn]

The air/fuel mixture screw and the pilot jet control the mixture when the bike is (rough numbers here) idle-1/4 throttle. Needle clip position effects the mixture from about 1/4 to 3/4 throttle, and main jet controls from about 1/2 to full throttle. Everything slightly overlaps each other thought still.

Turning the air screw out will make the mixture more lean, and turning in will make it richer.

[McDerry]

itsa 4 poke, bleeds in fuel not air. Turn out the pilot screw slowly till the bike likes to return to a stable idle after blipping the throttle. If it hunts for the idle its to fast.

[Nick_R_23]

Ok little update, I hadnt changed out the jet yet, but I did move the needle clip to the 2nd from the bottom, and it still does the crap when you ride and let off the throttle, it stays at that rev for a few seconds before going back to idle. But I got the jet and when I went to change it out, I checked the plug and its ALL black now, so everythings rich now and not lean, but why would it still hold the rev when riding it?

-Nick :TrikesOwn