Would this work??

I have a 1978 KZ750b3 twin. It has a set of mikuni carbs (CV 34's?? Something like that). The problem is that its running two rich even though I put a Mac's two into one pipe in it. It's always been running rich and I can't change the jets because they are these screw little ones that sit in the bottom of the airbox and I can't find replacements. So instead i was wondering If I put air pods on it Maybe that would lean it out enough?? I know this isn't the right way to go about jetting a carb but I can't think of anything better. Any ideas?? Suggestions?? Also does anyone know if I can still get pilot jets of different sizes for this bike. Tried Z1 and no dice. I'm thinking of maybe trying a leaner pilot to see if maybe that is what is causing it t be to rich.

Mikuni BS38 carbs are what's on the bike stock, BS34's in 82 and 83.

Rebuild kits are available for the 76-79 carbs.

Did you set the fuel level in the float bowl?
If the level is to high it will run rich.

Sorry I should have made myself more clear. There are rebuild kits for this bike (just rebuilt them last spring) but they come with only one size of jet, the stock one. As far as I can find that is. There really is no way to rejet that I can think of so i thought maybe this would be an option. I didn't set the fuel level on the float bowl though I didn't know that could make it too rich. I thought it just wouldn't run if it was to high. It does make sense though I'll try it this weekend and find out. the other thing I forgot to mention was that I can start the bike up and immediatley drive off when it is dead cold with no choke. After driving it around a little bit though I can notice a slight drop in power. It just won't pull from the bottom like it does right when i start it. I of course attribute this to it being to rich to start with but i thought I could add that in maybe it helps a little??

The small main jets are not available other than in stock size in the rebuild kit. Pilot jets are readily available. The type pilot jet is BS30/96 and I am sure Z1Enterprises carries whatever size in this type pilot jet you are interested in.

You use the term "running rich". I can only assume your plugs are sooty. If you have stock jetting, did it ever occur to you that the soot may not be air/fuel mixture related as relating to jetting? Could you have a dirty air filter? That will soot up your plugs. Could you have little or no valve clearances? That will soot up your plugs. Could you have a weak spark? We have an article on COIL REPOWERING on our website under wg's Tech Stuff index that explains how poor voltage at your coils will cause incomplete combustion (SOOTY PLUGS).

Do some research before mucking around with jetting on a bike with a stock airbox. Most likely the soot isn't the result of jetting.

Becker wrote:

the other thing I forgot to mention was that I can start the bike up and immediatley drive off when it is dead cold with no choke.

That does sound rich.

What pilot jet are you running? Stock on my '79 750 Twin was 40. They are available in sizes up to 60. This place has the full size range and will sell them in sets of two unlike so many other places that make you buy four at a time.

www.psep.biz/

Also, did you check the needle position? The stock setting for the BS-38 is the center slot, you can rich the heck out of it my moving to lower slots.

You did not say what main jet was in it. The stock one is 125 if my memory serves me. You can get rebuild kits with the stock jet. BTW, don't assume that the number on the jet is right, sombody drilled mine.

This place sells BS-38 rebuild kits for $19 and they come with the correct stock main jet:

www.loudfastugly.com/carbkits/carbkits.htm

When you said, "tried Z1Enterprise", did you call them? They have some stuff that's not on their website or they can get it for you. Just thought I'd add that.

wiredgeorge wrote:

BS30/96 and I am sure Z1Enterprises carries whatever size in this type pilot jet you are interested in.

You use the term "running rich". I can only assume your plugs are sooty. If you have stock jetting, did it ever occur to you that the soot may not be air/fuel mixture related as relating to jetting? Could you have a dirty air filter? That will soot up your plugs. Could you have little or no valve clearances? That will soot up your plugs. Could you have a weak spark? We have an article on COIL REPOWERING on our website under wg's Tech Stuff index that explains how poor voltage at your coils will cause incomplete combustion (SOOTY PLUGS).

Thanks for the information on the pilot jets, I'll be checking with z1 after I figure out what kind I have in it now.
It actually has a clean air filter, fresh plugs, a new coil, coil repowering mod, and I made the HEI system using the GM 400 module that I'm pretty sure I found on your website (thanks for that one by the way it works really well). I have never checked the valve clearances though but with 10,000 miles on the bike I doubt if they are to tight. The plugs are black and sooty which isn't really that much of a problem since the bike still runs fine but the last time I took it on a road trip It averaged 30 mpg and I wasn't riding hard just 65-70 mph over nice rolling hills. I knew it was rich then but I added all the electrical stuff this winter plus a macs 2-1 pipe. Since then I have just been using on sort stints a couple miles at a time. So maybe I will just have to wait and take it on a long road trip before I go messing with the pilot jets.

Its your bike and you can certainly do what you like but if you have never checked valve clearances, that is the FIRST thing I personally would do. Good luck.