Niceast you seem to be having fun.  Keep at it and you will prevail.

I know it's hard to follow all the advice you receive here on the forum, but you really should do your best.  One suggestion that has been offered over & over is to ditch those aftermarket components.

On 11/15 you posted: “the aftermarket jets are same a stock just different numbers.”

On 11/27 you posted:  ” Took the stock main jet and drilled out to 3/64” response was much better more smooth.”

The OEM Mikuni main jets come in .025 millimeter increments.  That would be .00098”.  The stock main jet is a #145.  That’s 1.45mm, or .057”.  You drilled your main jet with a 3/64” drill (.047”), which I assume means that it started out somewhat smaller than .047”.  In comparison, a #120 Mikuni main jet is 1.2 mm or .047”.  As you can see (if you actually removed metal when you drilled out your jet) the jet had to have been smaller that .047”.  That means it was smaller than a #120 Mikuni main jet.  A #120 Mikuni main jet is ten-sizes smaller than a #145 (120, 122.5, 125, 127.5, 130, 132.5, 135, 137.5, 140, 142.5, 145).  Drilling main jets doesn’t work well.  They are precise orifices, they come in .00098” increments, and the entry and exit tapers are critical to the flow through the jet.  Get the correct Mikuni jets, not aftermarket junk.  Genuine Mikuni jets only.

On 11/16 I posted a picture of the OEM needle jet and suggested you check the emulsion holes for obstructions.  Did you verify that you have the correct stainless-steel needle jet?  Are the small emulsion holes clean?

On 11/26 you posted a picture that implies your slide does not open completely.  Go back and look at the picture I posted on 11/16.  It shows side by side pictures of slides.  The one on the left looks like yours.  It’s not opening all the way.  The one on the right shows how it should be.  Which one do you have?

The holes you show in your TEV diaphragm are certainly a concern.  They will result in a manifold vacuum leak.  Air will be pulled from the pilot air jets (in the dome of the carburetor) through the diaphragm, and then into the vacuum port.  It will cause poor idle and you will have to compensate by backing out your mixture screw and/or installing an oversize pilot jet.  Note Dave's prior comment about how far your mixture screw is turned out.  You must replace the diaphragm.  

On 11/27 you posted:   “I forgot to mention I am running a nufoam air filter.”

Foam pod filters are a known problem.  Is your “nufoam” filter a pod filter or is it a direct replacement for the stock filter element?  A pod filter clamps to the carburetor, a direct replacement filter gets installed in the stock airbox.

Pod filters can cover up the air vent for the carburetor dome.  If that vent gets covered up or partially obstructed, it will prevent the slide from lifting properly.  This is the vent opening in question.

Please don't take this as being negative, but something isn't right.  

Needing a main jet that large to get over 60 mph???  It just doesn't add up. (If I had to guess it would be because the needle isn't OE and is probably also much larger than stock.)

For reference my bike will do an easy 75-80mph (but not much after that) on a 147.5 main.  Or it may be a 145 main?  I don't remember exactly anymore, but I know I'm running a little leaner than most on here.  It had a 155 main in there when I bought it and it was a turd.  

My point is that you should be able to get 90-95% full performance from stock jetting.  If you can't do that then you only have a solution for the symptom and not the problem.  

But if you are happy with what you have now, then more power to you!  

I had an 81 Honda CB650 that ran at low speeds fine, but at highway speed was too rich and would foul plugs. I rebuilt carburetors several times, went through many electrical possibilities, but found the only thing that corrected the problem was to prop the airbox cover open. It worked fine that way, so that's how I rode it.
I do not believe I corrected an airbox issue the 80's Japanese engineers got wrong. I compensated for a problem I was not able to find.

niceast wrote on 12/16/20 at 19:14:43:


Great. Another abrasive know it all expert.

Gary_in_NJ wrote on 12/17/20 at 17:34:28:


your right Gary.
I need to be more humble.
I know nothing.

closed thread, please
no addition progress regarding topic is being discuss, other than disagreed opinions of wether to diy-fix or buy-off-shelf parts.