KZ400 "Dirty Bird" Cafe (Winter mods)

Re: KZ400 "Dirty Bird" Cafe (Carb Question)

Wow that was a long and painful process. Good thing the weather has been pretty crappy here so it wasn't too painful watching my bike just sit their.

BUT... I finally got her running right. For the last month I toyed around with the idea of going 2-1 instead of using the stock carbs because jets are painfully hard to find for these stupid CV carbs. After attempting to order the jets from a local shop (for $14 each) and than finding out that they ordered them from someone who doesn't make them anymore, I finally found them online at jetsrus.com. $10 each would have sucked if they were the wrong size... but they are right. So I am happy. Runs like a champ!

Will post more pictures as I continue to add to the bike. Already making my "to do" list for next winter.

If you want to go 2-1 on your bike, or buy a couple Mikuni VM34's, I have 2 of them for sale in the "for sale" section :)
 
Re: KZ400 "Dirty Bird" Cafe (Carb Question)

PJmotorsports.com

They have all the jets you will ever need, cheap with stupid fast shipping. I'm in FL, they are in Oregon. get my jets in three days.
Im running pods with stock exhaust. 80 primary mains, 105 secondaries. runs great.
 
Re: KZ400 "Dirty Bird" Cafe (Carb Question)

reelinfeele said:
PJmotorsports.com

They have all the jets you will ever need, cheap with stupid fast shipping. I'm in FL, they are in Oregon. get my jets in three days.
Im running pods with stock exhaust. 80 primary mains, 105 secondaries. runs great.
Click to expand...

Wish I'd known that before ;-) Jetsrus got me mine in 3 days as well. I have K&N style intake, sportster mufflers and I am running 72 main and 92 secondary. Just 1 size up from stock on both.
 
Re: KZ400 "Dirty Bird" Cafe (Carb Question)

are you using diaphragm carb or piston carb? I have the diaph. style. i hate them. but now that I have it figured out their not so bad. tends to idle way too high with choke on, bike is very cold blooded. I start it and go take a piss before i ride away.
 
Re: KZ400 "Dirty Bird" Cafe (FINALLY)

reelinfeele said:
are you using diaphragm carb or piston carb? I have the diaph. style. i hate them. but now that I have it figured out their not so bad. tends to idle way too high with choke on, bike is very cold blooded. I start it and go take a piss before i ride away.
Click to expand...

Mine are diaphragm. Same deal. Idles crazy high with choke on. Can basically un-choke it as soon as I get it started.
 
Re: KZ400 "Dirty Bird" Cafe (FINALLY)

new here and i have a 79 kz400 also and am having jetting issues. i am current trying to tune with no filters and mufflers cut off. I have 70 main, 90 secondary main, 35 pilot, which should be stock, and its running rich. Plugs are blacks as ever. I can ride it, but it loads up alot at low rpm and feels sluggish. I would like to know peoples exact sizing of there jetting, main, secondary main and pilot.
 
Re: KZ400 "Dirty Bird" Cafe (FINALLY)

That's weird. Should be way lean.

Why are you running no filters and straight pipes? Did you try it with the filters and pipes on first?
 
Re: KZ400 "Dirty Bird" Cafe (FINALLY)

If your running rich with that setup you have bigger issues. Your plugs should be white and the motor overheating. Is it oil fouling? Compression test? I have 80/105 jets with stock pipes and pods, runs great. These carbs are extremely sensitive to float level! Make sure the floats are right, you might just be dumping gas in.
 
Re: KZ400 "Dirty Bird" Cafe (FINALLY)

Well... After almost 2 summer with no issues, I guess it's about time something went wrong. Now I am back to the fun trouble shooting stage.

Problem:
Was riding the bike home the other night and it just died. Sort of acted like it was out of gas, but it's not. Starts up just fine, idles, but after a few minutes of running it dies again.

Sort of acts like it's running rich and is fouling the plugs... however I don't know how that could be since I only went up 1 size on my jets and I'm running K&N style filters. My plus are pretty black, so it's not running lean. Just can't really tell if it's not getting enough gas, or too much. Given the black plugs, too much is probably a safe bet.. right?

Not sure where to start...

Should I rejet?
Adjust float level?
Rebuild petcock?
Clean carbs again?

I guess the weirdest thing is that it ran fine for over a year and just stopped all of a sudden.

All input appreciated.
 
Re: KZ400 "Dirty Bird" Cafe (Trouble shooting... need help)

have you changed your plugs in that yr...? they do go bad, even on a "perfect" running bike. And if there dark, it's rich. Rich where? I couldnt tell ya as I dont ride it. Idle, Main, air fuel mixture screw, could be could be any.... Plugs should be a very light carmal color ideally. If your gonna rebuild your petcock to fix this problem, than you might want to check your blinker fluid too...
 
Re: KZ400 "Dirty Bird" Cafe (Trouble shooting... need help)

Are both plugs black? If so, I doubt both carbs would 'go bad' at the same time. Black plugs could also be a sign that the spark is not strong enough, so it could be plugs, or any part of the ignition system (like coils, battery, etc.). I wouldn't dive into the carbs without checking and eliminating everything else first. If you haven't done so in a while, I'd give everything a check over like valve clearances, timing, air fiter (i.e. clean it).

If its been running good for two years, I wouldn't be rejetting. If you do go into the carbs, first thing to check would be the float level and if the shut off needle is seating good.

Do these carbs have a regular butterfly style choke or an enrichener as in the bigger KZ's. If the butterfly type, make sure they are not flopping closed. Its been known to happen on the Honda 350's a bit.

Let us know what you find out.
 
Re: KZ400 "Dirty Bird" Cafe (Trouble shooting... need help)

I have a set of hotter plugs. Tried them and it didn't help.

I checked the spark and it looks good. So probably not the battery or coil.

I guess I will start with timing and stuff before digging into the carbs. I guess what's throwing me off is how sudden it stopped working. One day fine, next day not.
 
Re: KZ400 "Dirty Bird" Cafe (Trouble shooting... need help)

And my petcock needs rebuilt/replaced anyway. Figure this is a good excuse to do it since i've been putting it off for so long.
 
Re: KZ400 "Dirty Bird" Cafe (Trouble shooting... need help)

Status update... Tore my carbs apart today and cleaned the jets. My pilot jet was super gunked up. Clean them, put carbs back together, checked timing etc.

Ran like a champ around the block. Best it's ran in a while... then did the exact same thing. Died, would start right back up, but ANY amount of throttle would kill it instantly.

Check the plugs when I got home and they are WHITE.

What's next? Rejet?
 
Re: KZ400 "Dirty Bird" Cafe (Trouble shooting... need help)

Finally switched the bike to a 2-1 intake and a PWK35 flat slide carb. Need to jet it, but it's running stronger than it ever has. Wonder how much those stock carbs were holding it back?

However... after installing the new carb and some nice clear fuel hose, it turns out my petcock may have ACTUALLY been the culprit all along. Fuel will flow strong to the carb for a bit and then completely stop. I don't think it's the float bowls stoping the flow because the hose goes from full to empty as if it's plugged at the petcock. If I switch the petcock from ON to PRE to Reserve it will flow freely again and then stop again on each setting.

Thinking I'll start by cleaning the petcock and then see if my tank needs re-lined.
 
Re: KZ400 "Dirty Bird" Cafe (Trouble shooting... need help)

treitz said:
If I switch the petcock from ON to PRE to Reserve it will flow freely again and then stop again on each setting.
Thinking I'll start by cleaning the petcock and then see if my tank needs re-lined.
Click to expand...

Check your fuel cap too... you might not be venting adequately.
 
Re: KZ400 "Dirty Bird" Cafe (Trouble shooting... need help)

Not sure what exactly that means... Do I NOT want it to seal completely?
 
KZ400 "Dirty Bird" Cafe (Trouble shooting... need help)

No, you want it to vent so the draining fuel doesn't create a vacuum in the tank stopping flow.
Your tank cap
Should have a vent check an make sure it's not blocked.
 
Re: KZ400 "Dirty Bird" Cafe (Trouble shooting... need help)

Alright. I'll have to see what I can find on the gas cap.
 
You must log in or register to reply here.

DTT Light or Dark

  • DTT Light
    • www.jadusmotorcycleparts.com
    www.lostapostle.ca/
    www.sparckmoto.com

    Spread the Love

    Back
    Top Bottom