Topic: If only I were as rich as my bike is running....

[zoo mob]

73 750 K3, I feel like I have done every stinking possible thing to get this bike to not run rich, all to no avail. Last season I switched to an electronic ignition and coils, so it should have good spark. Bike has a drilled out airbox with a freer-flowing K&N filter in it, carbs were synced last year, have been cleaned several times, and I just went down from 120's to stock 110's, last year I set the float levels at what I thought were correct. Thought the recent jetting would do the trick, but 25 miles later, the plugs are black as night. I saw in an earlier thread someone mentioned the emulsion tubes, what are these, and how could they effect things? Another thing that was mentioned was having the floats set too high, could this be the case? Thanks for your help, I just want this thing to run right, I've been chasing this crap for two seasons!

[Hush]

If your float levels were too high I would expect leaking float valves.
I suppose it is too late to return to the original air box that was designed for the bike?
Seems most rejetting and rich running issues stem from the addition of pod air filters.
I'm also not sure about what some on here describe as "emulsion tubes" unless it is the longish brass tube (main nozzle) that the main jet screws into, this has very very fine holes set around in it at different levels and I'm always particular about cleaning these out (I use a fine fishing nylon).

[zoo mob]

I actually do have an undrilled airbox, but that would just make the problem worse correct? I also failed to mention my exhaust setup, stock 4-4 with a few rust holes on the bottom for better flow. What the hell is causing this problem?!

[Bob Wessner]

Thought the recent jetting would do the trick, but 25 miles later, the plugs are black as night.

Under what circumstances did you check the plugs, an actual chop or just pulled and looked at them after a ride?

[Duke McDukiedook]

Sooty black or oily/gassy black?

[cycleman]

Your original post indicates that you haven't taken the carbs out and really, really cleaned them.ie: what's emulsion tubes.  I would do this first and put everything back to stock and go from there.

Rich running can be anything from choke sticking on, floats too high, needle in wrong position, wrong jetting etc. The emulsion tubes break up the fuel into fine drops.

I know most don't believe it but bikes will run better with the stock air cleaner.  Anytime you change anything on the intake side of an engine you can have more runability issues. These take more work to sort out. There is a very narrow ratio of fuel/air ratio for optum running. Changes on the exhaust side are not usually as much of an issue.

Also trying to read old plugs is not the best.  Put in some new ones and then do a plug chop.  Also some sypmtoms on what bike is doing other than colour of plugs, ie: bike bogs under accleration, flat spots etc.

[ekpent]

Kind of a long shot Andrew but what kind of oil are you using on your KN filter and is there a chance that it may be over-oiled. ??   Eric

[Spanner 1]

Cycleman,....that's got to be Carb Quote Of The Year..!!
      " There is a very narrow ratio of fuel/air ratio for optimum running "
 A definite +1 on that statement !!

[Spanner 1]

Your bike runs best on a 'fuel froth'/air mix....the fuel gets 'frothed' by air sucked thru' the main jet bleed (tube ) acting on the emulsion tube holes and metered by the needle rising and falling according to amount of throttle........a fancy way of saying it's time to take the carbs apart and clean them.
If the air passage is blocked ( common ) the stream of fuel is just that a solid stream instead of a much less dense froth of fuel ( much leaner )....IMO.

[fmctm1sw]

No real input but it's reassuring to see someone else fighting mixture issues.  Do some chops maybe, I got a 350f chop post out there...

[GammaFlat]

My K6 "mucked up" (sooty black) plugs in less than 100 miles.  I believe it was the "emulsion tube vents".  I love Spanner's description (froth) of the problem . 

It is the least obvious visually 'cause... well... you can't see 'em.  Since fuel doesn't really flow through this spot, it's probably not gonna fix itself either.  The "tube" you're gonna clean makes a 45 degree turn as it heads for the "top" of emulsion tube, which makes it extra difficult to "navigate". 

My theory is that it plugs or partially plugs right at the end.. closest to the emulsion tube - (because it's the hardest spot to reach, of course).  I used a guitar string and very fine strands of copper wire twisted as well.  It's harder to get the twisted softer copper through the hole though.  Liberal use of some pressurized cleaning agent between "wire runs" and high pressure air both help. 

The orifice you are looking to clean is a brassy looking thing on the airbox side of the carb at the edge of the "inlet".  HondaMan posted pictures of one of these about 2 months ago. 

[fmctm1sw]

For reference I guess it's the middle tube.  Honestly I didn't think about cleaning mine either.  I did my idle passage next to it but not that one    I wonder if you could shine a light into it and see it from the main jet tube in the carb?

[BlackMax]

73 750 K3, I feel like I have done every stinking possible thing to get this bike to not run rich, all to no avail. Last season I switched to an electronic ignition and coils, so it should have good spark. Bike has a drilled out airbox with a freer-flowing K&N filter in it, carbs were synced last year, have been cleaned several times, and I just went down from 120's to stock 110's, last year I set the float levels at what I thought were correct. Thought the recent jetting would do the trick, but 25 miles later, the plugs are black as night. I saw in an earlier thread someone mentioned the emulsion tubes, what are these, and how could they effect things? Another thing that was mentioned was having the floats set too high, could this be the case? Thanks for your help, I just want this thing to run right, I've been chasing this crap for two seasons!

Good luck.....I have the same problem, but can't solve.  The emulsion tubes weren't the problem here.  I was hopeful; and pulled them out; but,  they were perfect.  It's easy.  Just drop the bowls and unscrew them.  It'll be obvious.   You'll have to be sure air is getting in from the air jet to the emulsion tube. 

Is your exhaust black?  Mine seems to be running rich (smells of gas, fouling plugs that smelled of gas when pulled)....but then I realized I've never under any situation ever seen black exhaust smoke.  Therefore....I doubt that's the problem.  I'm starting to realize that these bikes are just one problem followed by 3 more.  I hope you figure it out, so I can solve my problem as a result.

[Mattbastard]

Pony up the dough for a Wideband O2 device.  They're about $200 on ebay and make tuning a cakewalk, not a crap shoot.  I put one on my custom 4-1 on my 650 and come to find out, it's running really lean...

[fmctm1sw]

Pony up the dough for a Wideband O2 device.  They're about $200 on ebay and make tuning a cakewalk, not a crap shoot.  I put one on my custom 4-1 on my 650 and come to find out, it's running really lean...

I saw some other threads talking about O2 sensors.  Is that $200 all inclusive for what you need?

[Mattbastard]

Yes, often times with the O2 bung that needs to be welded into the exhaust. 

The only problem is that if you have the stock 4-4, you'd need to fabricate up something to get exhaust readings up in the muffler.  I've seen some good ideas to accomplish this on the net. 

[Spanner 1]

NIce....02 sensor , but wont clean-out your air bleed passage for you !!!!

[ekpent]

You tell' um Spanner!!!!! Good old fashioned elbow grease keeps them running

[IainC]

Just had to comment on the thread title, made me really laugh out loud