Engine dies as throttle applied...ideas?

I also changed the carburetors and put in ones from a 1980 and sealed the main jet hole so there was only a needle jet and pilot jet, like the spectre had in the first place. I didn't think to check the float levels though...just assumed they were good when I got them....

Spenzher wrote: I also changed the carburetors and put in ones from a 1980 and sealed the main jet hole so there was only a needle jet and pilot jet, like the spectre had in the first place. I didn't think to check the float levels though...just assumed they were good when I got them....

Uh, sealed the "MAIN JET HOLE"???
That can't work. You need to rethink that completely. Make the carb have All of the original circuits, and only increase the jet sizes for your POD filters. Hopefully they fit correctly and don't cover the Air Jets.

Spenzher wrote: sealed the main jet hole

Well, unseal it. :laugh: I guess I was right about it not getting any fuel.

It has been my experience that if the bike ran fine before working on it then suddenly start running like crap after working on it then it was something I did. If you did not change any of the valve shims then I would look at the other things you might have touched, vacuum lines to carbs and petcock, ect Re-check your work.

Motor Head wrote:

Spenzher wrote: I also changed the carburetors and put in ones from a 1980 and sealed the main jet hole so there was only a needle jet and pilot jet, like the spectre had in the first place. I didn't think to check the float levels though...just assumed they were good when I got them....

Uh, sealed the "MAIN JET HOLE"???
That can't work. You need to rethink that completely. Make the carb have All of the original circuits, and only increase the jet sizes for your POD filters. Hopefully they fit correctly and don't cover the Air Jets.

CrazyDuck wrote:

Spenzher wrote: sealed the main jet hole

Well, unseal it. :laugh: I guess I was right about it not getting any fuel.

Hold on gentlemen. There are a total of three jets. One main jet, one needle jet, one pilot jet. Ironically they call the needle jet a secondary jet. The main one is for transitioning between pilot and needle. Now, on the carburetors that were originally on my bike, they didn't have main jets. They had a needle jet and a pilot jet. I am merely creating that same scenario even though there are main jets in the carburetor I am using now. If I were to use the same main jets, the actual bike would be getting way more fuel that it had beforehand.

baldy110 wrote: It has been my experience that if the bike ran fine before working on it then suddenly start running like crap after working on it then it was something I did. If you did not change any of the valve shims then I would look at the other things you might have touched, vacuum lines to carbs and petcock, ect Re-check your work.

Yeah...I definitely messed something up. Hm.

You don't plug anything off just because the other carburetors did not have it. They are designed differently and cannot be expected to run if you start plugging things off or massively alter things.

CrazyDuck wrote: You don't plug anything off just because the other carburetors did not have it. They are designed differently and cannot be expected to run if you start plugging things off or massively alter things.

I'm not so sure about that but maybe someone else can chime in. I'm using a carburetor pulled off of a 1980 kz750 and my bike is a 1983 kz750.

What carbs are you talking about here, the Mikuni BS34 or the Keihen CV's? All the Keihen's and Mikiuni's have main jets. The main jet is attached to the bottom of the needle jet and regulates the amount of fuel going into the Needle jet. If you plug the main jet then no fuel is going to get to the needle jet so the engine will not run past idle.

baldy110 wrote: What carbs are you talking about here, the Mikuni BS34 or the Keihen CV's? All the Keihen's and Mikiuni's have main jets. The main jet is attached to the bottom of the needle jet and regulates the amount of fuel going into the Needle jet. If you plug the main jet then no fuel is going to get to the needle jet so the engine will not run past idle.

Oh boy, I hope I got this right ...but I plugged the unthreaded one in the picture. The one in the picture is the original carb, which I unfortunately can't use. To my knowledge it only uses a needle jet and pilot jet. No main. So I thought I could use these other 1980 cv34 carbs and just plug the main jet, thus making the fuel intake less, and create the same settings as the original carb.

All of these carbs will have Main Fuel Jets, allong with Needles and needle jets, pilot jets, starter jets, air bleeds etc. Plugging off something will cause what your experianceing. So pull the carbs, take some photos of what you did, and everyone can see if its fixable.

Could be mistaken, but thinking stock carbs on the bike at hand are 34mm Keihin carbs

This link is to an article in KZr's FILEBASE that may prove helpful.

Click here > www.kzrider.com/filebase/doc_download/47...-shop-manual-via-omr

Good Fortune!