1982 KZ1000 Police Jetting question

[nfakbc]

I'm looking for some advice on jetting my 1982 KZ1000 Police bike. The bike currently has free flowing exhaust, air box removed and pod style air filters. The rest of the bike is stock. Is there anybody out there with a similar setup that wouldn't mind letting me know what size jets they used? Thank you in advance.

[kopcicle]

needles should be shimmed up about 1.5mm mains @ 137.5 to start and IMHO I don't see needing more than 140's . I remember Sudco having #40 non bleed pilots . Idle mixture screws should see lean missfire around 1 3/4 turns and rich missfire about 3 turns out . An easy check to see if you are still running lean is to cover the filters with cotton socks . If it improves drop the needles remove the socks and try again with an increase the main jet size .

~kop

[nfakbc]

I just threw a set of 137.5 main and 40 pilot jets with ~1.5mm shims and my bike is running incredibly rich. I thought it was running decently well for a 15 mile ride until I figured out I went through 2 gallons of gas. The next morning I went to start the bike and it wouldn't start, pulled the plugs and they looked horrible.

My only mods are the airbox has been removed with uni pod style filters and the factory mufflers were cut off and replaced with 2004 Sportster mufflers (the center of the mufflers have been punched and are now straight through but still have packing).

Is it possible that my jets at 137.5 with the minor mods are actually so large that I average 7.5mpg or should I be looking for something else carb related? The bike has roughly 50k miles, the valves are a little loud and probably should re shim them but my compression ranged from 130-140 psi cold.

Any advice would be appreciated as the Seattle summer is coming to a end.

[StarGate]

I ran pods and a kerker 4-1 for a few years and 140/40 did just fine in the BS34 CV carbs. Same engine as yours.

[nfakbc]

That is the jet setup I noticed most people are running. Does anyone have any clue what could be causing my bike to run so rich?

[StarGate]

What carb mods/jets are you running and are you still running BS34 carbs?

You really haven't explained what your bike is doing or any symptoms you've been having.

[nfakbc]

My only mods are no airbox/ pod filters and straight through mufflers. I'm currently running 140 main/ 40 pilot jets. My carbs are the stock carbs that came on the 1982 kz1000 police.

[kopcicle]

Originally Posted by nfakbc

I just threw a set of 137.5 main and 40 pilot jets with ~1.5mm shims and my bike is running incredibly rich. I thought it was running decently well for a 15 mile ride until I figured out I went through 2 gallons of gas. The next morning I went to start the bike and it wouldn't start, pulled the plugs and they looked horrible.

My only mods are the airbox has been removed with uni pod style filters and the factory mufflers were cut off and replaced with 2004 Sportster mufflers (the center of the mufflers have been punched and are now straight through but still have packing).

Is it possible that my jets at 137.5 with the minor mods are actually so large that I average 7.5mpg or should I be looking for something else carb related? The bike has roughly 50k miles, the valves are a little loud and probably should re shim them but my compression ranged from 130-140 psi cold.

Any advice would be appreciated as the Seattle summer is coming to a end.

If at any time in the bike's life it has sat for any length of time the float needles may be leaking past . The needles are vitton (rubber) tipped and under close inspection you may find a ring around the tip . Although the needles may seat at rest engine vibration may allow excess fuel into the carb throat .
The abortafact that we have for a petcock may also be to blame but would only soak one cylinder and only if the fuel side and the vacuum side were holed . You would also see significant leakage from the vacuum valve .
Incorrect assembly or parts left out of the carb can be to blame also . The pilot jets are under an aluminum plug with oring that has to be there for correct metering .
Not being there to see the carbs prevents me from seeing what might be an easy diagnosis . My IM's are exposed just for this kind of issue . If you wish to collect a detailed photo record and host or email it I'd be more than happy to help .

~kop

[nfakbc]

I just went through my carbs today and everything inside looked good. I did replace the o-rings on the aluminum plugs capping off the pilot jets and the o-rings on the brass pieces that press into the carbs (the ones that the float needles seat in) to make sure no fuel was leaking past.

As for the float needles, mine do not have a vitton tip but rather just come to a sharp point. I tested to make sure they sealed when I had the pieces off nothing seemed to leak through.

Nothing changed after I did this. Is there any way that 137.5's jets could be too large for my minor mods to cause my rich running issue? I'm not all that familiar with these newer vacuum style carbs but don't you typically go 10 up for pod filters and 10 up for free flowing exhaust with mechanical carbs (my stock jets were 122.5 so I'm only 15 up from stock)?

[StarGate]

The jets are not the problem. How did you test to see if the needles were closing off good? Did you check the fuel service level on the carb or check/adjust the float height? Any chance you might have over oiled the pods? Have you check to make sure it has a strong blue spark?

[nfakbc]

Thank you for the response, I really appreciate the help.

To test that the needles were sealing I just threw the needle in the housing when the setup was out and blew into them to make sure there was no air blowing by. As for the fuel service level on the carbs I'm unsure how to check that. What would be the chance that every carb's fuel level was off the same amount as when I pull the plugs they all look the same? The pods were very lightly oiled with the foam filter oil and don't believe they are starving the engine for air. I will check tomorrow to see if I do have a strong spark.

[StarGate]

If someone set the float height and had the wrong measurement for it or didn't know the right way to set them then it's very good odds they they are all wrong. What they would have set one at, they would have set them all at.

[nfakbc]

Update, I've read a few posts on the net about the coils receiving less power than they want due to the age of the wiring etc. I ran a 10 gauge wire from the battery to a relay to bypass the factory wiring for that section. The spark which seemed a little weak before now seems to be a lot stronger, I now have no doubt the ignition side of the bike is working fine. The bike seemed to run great on the first ride but I pulled the plugs when I came home and the bike still seems to be running very rich.

Anything else I should check before I give up on this project?

[kopcicle]

Yeah , drop the needles if you haven't already .

~kop

[nfakbc]

Gave up on the bike for a little while but got some inspiration so I'm back. Just for the hell of it I threw a set of 110 main jets I had sitting around in and even with smaller than stock jets I'm still running incredibly rich. I threw a wideband o2 on the bike and I'm running 10.8 afr at idle!!!! Anything else I should try before either scrapping the project or switching to Megasquirt FI????

[wdhewson]

Hi guys. Tuning just one thing is a difficult approach. Confirm correct valve lash, and a strong spark at the right tme. Then get at the carbs. These carbs are super precise and finely made instruments and need to be set up by the book with all passages and jets open and without deposits. Get the mixture suited for your climate and riding style for a medium soft throttle and a near white spark plug procelin.

[kopcicle]

you have a PM

[zoro]

Originally Posted by nfakbc

Gave up on the bike for a little while but got some inspiration so I'm back. Just for the hell of it I threw a set of 110 main jets I had sitting around in and even with smaller than stock jets I'm still running incredibly rich. I threw a wideband o2 on the bike and I'm running 10.8 afr at idle!!!! Anything else I should try before either scrapping the project or switching to Megasquirt FI????

It does not matter what size mains you put in those carbs if your checking the exhaust at idle rpms! Your "Pilot" circuit is the only circuit feeding fuel at idle speeds. Index the throttle and read the plugs.