Topic: Running very rich. FLoat Levels? 78 750K

[BobbyR]

I took everyones advice about my starting cold problem. I pulled the carbs yet again, gently pulled out the slow jets and passed guitar sting through them.  I fact I made double sure all passages are clear. I decide to check the floats which seemed a bit low. I followed all the posts a pictures and set the jets at 14mm. She now starts amazingly well, but you can almost see puffs of unburned gas coming out of the pipes. The smell is unbelievable. Could have set the floats improperly and am partially flooding. I have the mixture turned in all the way shut. Yes the plugs are black and sooty. HELP!

[Lumbee]

...running rich is gonna come from jetting, not the float level...what is your history with the bike.  Was it running rich before you tinkered with the carbs?  What main jets do you have installed?

[scondon]

The floats are set at 14.5 mm. The jets are screwed in until seated. If you set the jets to 14mm? then they will be too far out and the jet needle will be thinking that you are at wide open throttle while your slides are allowing only air for idle. Or at least that's the way I read your post??

[BobbyR]

I miss wrote post. I cleaned the slow jet and tried to set the floats at 14mm. They really took a great amount of adjustment to get them to 14mm when the tabs touched the needles. The history is after the carb rebuild I could not get it to start cold with full choke(verified) without pumping the the throttle to keep her lit till warm. I was advised to pull the slow jets and cleaned them and while I was at it I decided to check the float height. Now I can fire it up with little choke and you can see puffs of unburned gas coming out of the pipes. I can minimize those puff and make her idle smoother by closing the mixture screws all the way closed. i am wondering if it is flooding a bit. The bike is stock with the 120 mains, original airbox, proper filter and 4 into 4 exhausts.

[eldar]

Well first off, main jet size for stock is 110. So if you have 120, then they have been changed. The mains however will not affect the idle performance. When you had the carbs off, did you adjust the accel pump arm? There must be a gap between the actuator and the arm. It is about .08 or so. Also, set the floats closer to 15mm. this will drop the float level in the bowls slightly and could help. also make sure the pump is assembled correctly. There is a spring inside the pump the closes it. The spring should be between the cap and the pump.

so now lets move to the mains. At higher rpms, do you run rich there? Do a plug chop and see what your plugs look like while at high rpm. if you are running stock and have 120s, I would see about getting the 110s unless you are not running rich.

[scondon]

I miss wrote post.

 I was just yankin' yer chain. Sorry about that,Bobby

   I thought that stock mains were #110 for your bike. Not that the main jets would have any effect on your idle issue, just wondering.

    Seating the mixture screws all the way to get the bike running better certainly points to getting too much fuel. The stock setting of 1 1/2 turns out was too lean on my 750F and I settled in on a richer mix at 2 1/2 turns out. Turning them all the way in would basically shut off the fuel to your idle jets so one would wonder where the fuel is coming from to run your bike at idle?

    Having the floats set too high could cause a rich condition, or at least that was my experience, but it wasn't as extreme as you are describing. Gas spilling out the overflow was my biggest indicator that I had set the floats improperly. Still, if you had to make "a great amount of adjustment" to set each one it might be worth a second look.

    Also, there is the accelerator pump to think of. I've put the #2 float bowl back on without paying attention to the accel. pump activating arm and whether it was routed properly. Due to my error it was fully depressed at all times.

    And finally, I've re-installed jets just to have them come loose and fall to the bottom of the float bowl. That definitely caused a rich condition

   I know I'm not giving any great advice to help with your problem. Just thinking out loud really


Damn Eldar, I type too slow. I'm also too stubborn not to post what took me 5 minutes to peck out  

   Sorry for any repeat of Eldy's good advice

[jdpas29]

yeah.... switch to 110 mains in any event if you have stock setup or close to it as far as exhaust and airbox.  check to make sure that there isn't some sort of restriction on your airflow.  if there is, it will cause the bike to suck in more fuel than is needed.  set your adjuster screws to 1 3/4 turns out to start with.

[TwoTired]

To reinforce (hopefully) what others have said, know that the slow system provides fuel for idle speeds.  If you can close this system off and the bike still idles, then it is drawing fuel from some other source.  The only options are from the main throttle valve (worn needles or throttle valve orifice), or the accelerator pump supply.  One of these two is leaking more fuel than it should.

Cheers,

[BobbyR]

I really need to thank you guys. I took the weekend off since there is just is much wremching my wrist can take these days. I will certainly check the accel pump since I did take it apart to be sure that was clean. I am the second owner and the first raced cars I found to notes in the shop manual about improving the bike. It had 6K miles on it, his friend was killed during a ride. I will bring the floats down again as I think I blew that completely. I did use the floats and valves from the rebuild kit. For a bike that would not start without a lot of pumping when cold, to being able to start cold with hardly any choke, something has really changed.