Help!! I Lost lots of mpg with New Mikuni Carbs

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Help!! I Lost lots of mpg with New Mikuni Carbs

23 Apr 2015 17:13
#669336
I got rid of the original carbs on my KZ440, and I put two new mikuni VM28's on. Its been a huge disaster. It runs decent now, but I used to get over 40mpg, now I am getting around 23 mpg. Does anyone have any ideas? Could I run the 440 on just one mikuni carb? I also have Pod filters on. The original air box and original carbs are gone for good and not coming back.

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Re: Help!! I Lost lots of mpg with New Mikuni Carbs

23 Apr 2015 17:23
#669337
Why did you get rid of your old carbs? Check your plugs. Are they black?
Steve
Z1b1000 1975 Z1b
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229

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Re: Help!! I Lost lots of mpg with New Mikuni Carbs

23 Apr 2015 19:21
#669351
Yes, the plugs are black. I was very uneducated about carbs and mechanics at the time. Long story short, someone told me they could tune them for me, to work better with pod filters, and they ended up ruining them. So i got mikuni VM 28's and it is working well now, however it uses way more gas.

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Re: Help!! I Lost lots of mpg with New Mikuni Carbs

23 Apr 2015 20:54
#669367
Any other mods? Sounds like they are running way to rich. Unfortunately pods make are a PIA to tune with. Now that I have stated the obvious, all I can suggest is to get the jetting right. Once that is accomplished the MPG should bounce back a bit. What size where the OEM carbs? If the only changes are pods and a header you only need to be running a bit richer than you were on the original carbs.
Jon
1977 KZ1000a1
Mesa, AZ
Phoenix Fighter Project

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Re: Help!! I Lost lots of mpg with New Mikuni Carbs

23 Apr 2015 21:15
#669371
Pull a pilot and main jet and tell us what you have.
Steve
Z1b1000 1975 Z1b
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229

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Re: Help!! I Lost lots of mpg with New Mikuni Carbs

24 Apr 2015 08:41
#669403
I have not put any after market exhaust pipes on. Is that what you meant by header? Someone told me if i bought a new exhaust system it could reduce the MPG since it would be getting better air flow through the engine. However, If i can I would like to avoid spending much more money.

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Re: Help!! I Lost lots of mpg with New Mikuni Carbs

24 Apr 2015 08:41
#669404
Ok, I will pull the pilot, and main jet, and get back to you.

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Re: Help!! I Lost lots of mpg with New Mikuni Carbs

24 Apr 2015 08:45
#669406
So you haven't looked at the jets yet? A better exhaust will improve the performance, thus better mileage.
Steve
Some people just like to hear themselves talk.
Z1b1000 1975 Z1b
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229

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Re: Help!! I Lost lots of mpg with New Mikuni Carbs

24 Apr 2015 14:33 - 24 Apr 2015 14:34
#669434
28 mm carbs are WAY TO BIG for your engine.
Last edit: 24 Apr 2015 14:34 by baldy110.

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Re: Help!! I Lost lots of mpg with New Mikuni Carbs

24 Apr 2015 15:01
#669437
I don't think that is the case, because his KZ400 is a twin. According to kz400.com the 1977 KZ400-D4 actually came with new 32mm CV carbs. That sounds huge to me, but I guess since each cylinder is about 200cc it's the equivalent of an 800cc 4 cylinder engine. Ed
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)

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Re: Help!! I Lost lots of mpg with New Mikuni Carbs

24 Apr 2015 15:32
#669441
I believe the 440 came stock with CV34s on it, as part of an effort of kawasaki to standardize carbs across the lineup.
'78 1000 Long Term Project
 '80 750G
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Re: Help!! I Lost lots of mpg with New Mikuni Carbs

24 Apr 2015 17:29
#669451
I'm still waiting on the jet size and pics of the plugs.
Steve
Z1b1000 1975 Z1b
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229

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