[Exaviator]

While awaiting my engine parts, today I tried to look into why it was running rich and putting out a bit of black smoke-especially at idle. Also, when I took the head off I noticed that it was all black on the piston top.
I had already taken the carb apart and cleaned it thououghly, but I took it apart again and checked that the main jet needle was indeed in the third grouve down and that it was well synced with the butterfly valve. All the orifaces are super clear and the pilot jet is set at 1 1/2 turns out from light seat.
Another thing that I noted when it was running earlier was that the idle set screw would not boost the idle RPM-even when screwed fully in. Could there be some screw end extension missing? Can't tell by diagrams. Also, the choke(enricher) may need a new O ring. How critical is that??.
I lost the pilot screw setting so I was forced to pre set it and then use the outlined procedure of turning it in till the engine quit and then backing it out by 2 turns. That seems a lot.
I am pretty carb savvy from working small engines for the last 20 years---just need 350 carb 101. So----any pointers?????

 

[Potato_Gun]

First off, you should check and clean your air filter, a real dirty one can richen up the mix pretty good. And yes, if the o ring on your enricher is leaking fuel past it, it will also cause a rich condition.

Is your bike burning alot of oil?

 

[Exaviator]

Good thought on the air filter. It seems to be really oil soaked but looks fairly clean. Come to think of it, it started blowing black smoke as soon as I installed the air filter. Engine has new bore with 20 thou OS piston and rings and new valve seals. No oil burn.
i have a box of O rings that is sure to have one that will fit. Gotta read up if they are fuel compatable.

 

[Exaviator]

Took it all apart again to replace the cam chain and kick start clutch. Also took the carb completely apart again and recleaned it--nothing in there, and everything looks to be in order.
Two things I suspect may be the cause
--worn main jet and needle
--the enricher may be effed up, needs new O ring seal and it may not be properly seating once it is moved to OFF.
The thing will run and rev up like crazy, but I can see black smoke and the plug fouls very quickly. I now have the pilot jet set at 1 turn out and it didn't start this time---battery is recharging presently. Takes time to fill the float bowl and the battery was almost gone, so am waiting.
Any and all suggestions are welcome.

 

[Helmut]

You'll probably have to replace the o-ring on the starter enrichment valve before you can tell much about it.

 

[Exaviator]

Yes, I will do that. Is that a special O ring, or do you think any O ring of the right size will do? I am thinking they may not have the proper one.

And I have to ask this. How in blazes do you get your hand in under the carb of a running and hot engine to fiddle with the pilot screw. Just too small a spot and too many burned hands, so I more or less have to wait till it cools and then do trial and error settings. Not sure if the pilot jet is the problem or not. They say to turn it in till it quits then out two full turns. Mine is only about 1 1/2 turns out and it is puffing black smoke at or near idle. And it won't idle up with the idle screw. What gives here. Float level too high? Doesn't seem to be adjustable.

 

[Helmut]

Is that a special O ring, or do you think any O ring of the right size will do? I am thinking they may not have the proper one.

A regular o-ring should work as long as it's the right size.

And I have to ask this. How in blazes do you get your hand in under the carb of a running and hot engine to fiddle with the pilot screw. Just too small a spot and too many burned hands, so I more or less have to wait till it cools and then do trial and error settings.

Yeah, I know what you mean. If you have big hands, it's hard to get them in there to the pilot screw. I have one of those flexible screwdrivers that I use, but a lot of times it's still hard to get to it with that. Sometimes, I just have to endure the pain while adjusting it and sometimes I can't and have to let it cool down and turn it a little at a time.

Not sure if the pilot jet is the problem or not. They say to turn it in till it quits then out two full turns. Mine is only about 1 1/2 turns out and it is puffing black smoke at or near idle. And it won't idle up with the idle screw. What gives here. Float level too high? Doesn't seem to be adjustable.

If the o-ring is bad on the starter enrichment valve, that might be the cause of the black smoke. I don't know why it won't idle up with the idle screw. The idle screw just pushes the throttle linkage to open the throttle. Is the idle screw opening the throttle plate? And you're right, the float isn't adjustable.

 

[Exaviator]

I am thinking that it won't idle up because of the relationship between the butterfly valve and the slider. Maybe I need to bend the tab so the slider starts to move up just a tad sooner. For sure, the idle screw is raising the throttle plate and starting to open the butterfly, but that may be of no use unless the slider has already started to lift. I will get it because it all seems to be in half decent condition.

 

[shadetree]

I am thinking that it won't idle up because of the relationship between the butterfly valve and the slider. Maybe I need to bend the tab so the slider starts to move up just a tad sooner. For sure, the idle screw is raising the throttle plate and starting to open the butterfly, but that may be of no use unless the slider has already started to lift. I will get it because it all seems to be in half decent condition.

yep..bend the tap up on the iddle cam..sounds like it's not lifting it up..also..try adjusting the idle from the handle bars..right hand side..there is a adjustment screw there to back out..this will also increase your idle.

 

[Exaviator]

I noticed that the manual says to remove the "PLUG" as well as all the jets after you take off the float bowl. I have never removed the plug, and I assume that it is that little piece of rubber stuck in a hole. There was never any mention of that plug again(during reassembly) What is under that plug????

 

[Helmut]

I noticed that the manual says to remove the "PLUG" as well as all the jets after you take off the float bowl. I have never removed the plug, and I assume that it is that little piece of rubber stuck in a hole. There was never any mention of that plug again(during reassembly) What is under that plug????

Yeah, it's the little rubber plug. I usually pull it out, so I can blow through all the passageways with an air hose. I can't remember anything being in there, though, I think it just plugs up the passageway for the starter jet, the starter jet screws in the side of that little tower that it plugs off. If you have trouble getting the rubber plug back in, just wet it a little bit and it will go all the way back in.

 

[Exaviator]

While awaiting an answer, I just took it out and saw what you already said. It just plugs the end of the starter jet. Anyway, I ended up setting the pilot screw at 3/4 turn from light seat and said--enough--and put it back on the bike. It started up almost immediately and now seems to be running freer and with no black smoke. Maybe I got it.

Went to Honda for the little enricher O ring and they only had the complete enricher needle assembly for a meagre $55.. No thanks. Don't think that O ring is of much consequence anyway--just to keep gas from coming out the top. Can't see it upsetting the mixture.