kz900 with 1015 tuned correctly

roll6285 wrote: Okay so just to clear up my parts,

I have a Dyna III electronic ignition with the green coils
My carbs are off the old Z1 I believe they are off the 1975..... and who knows they could be shot!! But they honestly don't look bad!

This is just a thought and a stupid one I am sure!!! lol but the bike has a mono shock on it now and it has a lot steeper rake or angle.... or whatever you want to call it! would this affect the carbs performance?

Maybe Ill just load a photo! if I can figure it out!

Have to correct myself here. I used a 155 jet and the needle jets from
a set of 26mm carbs in the 28's. The holes in the 28mm model carbs needle

jets are much larger and ....

long story short, I think u might be rich and the plugs could be black.

Heres another story... Both the 26's and the 28's never needed choke
unless it was real cold. Only then it would need choke for start, and in seconds
I could close it all the way and go. Anytime it was 60 or above and the bike had
been setting all day it was a kick and it would literally jump to life and zoom to wide open with no hesitation.

So idle can be effected by the main? Well in my own experience, HUGE.

Ever had a pilot air passage block with dirt while riding?

Top end flutter results and no power.

Now I got these dagon 34's and the leanest idle mix on the...

I miss that kick and go. The 28's were kindof crappy low and mid
but that top end was strong and put down some road!

The 34's take the cake though, the strength is much more
than the 28's could ever do.

The idle and mid on these is easy enough, it's the top
that needs to be strong through the redline on these,

otherwise you don't even want them on there, they can be
real funky up at mid top and high top. If they aren't tuned
right.

I had to find me some road... and don't even bother if you

don't have enough main jet, cuz it ain't gonna happen.

All right that's enough

But that's another story..

roll6285 wrote: ...Maybe Ill just load a photo! if I can figure it out!

If using Windows operating system --



Good Fortune!

the guy who did my carbs used a chart to determine the correct jetting (which was almost perfect) I think this is the chart he used but looks close to what he was describing when telling me about it



Motorcycle Carburetor Jetting Recommendations.

Copied from the xs11 list @ www.xs11.com This should give you an idea of which way to go in regard to different Intake Exhaust configurations.



Note:

This document is based on Mikuni Carburetors. But the theory follows through on all carburetors. Be aware that Mikuni Main jets increment in steps of 2.5, Hitachi Main jets increment in steps of 2.0. Hitachi Main jets (screw in style [Yamaha XJ's] are available in sizes from 110-134 in increments of 2.0. All this means that if you find you need to go up 4 steps on the main jets according to this chart (2.5x4) the step up would be 10.0. For Hitachi mains the step up would be 5 jet sizes (2.0x5) since following this chart for Hitachi mains would put you at 8.0 which is very close to 7.5 which would be 3 steps according to this chart.

Jetting Recommendations
by Denny Zander

Here is a simple set of jetting guidelines that have worked for me. For those considering jet changes, this might help select a starting point.

1 jet size for custom 4 into 2 exhaust

2 jet sizes for 4 into 1 exhaust

1 jet size for K&N filter (single inside airbox)

1 jet size for drilling out the bottom of the airbox

2 jet sizes for both single K&N and drilled airbox

2 jet sizes for individual filters

2 jet sizes for no muffler (open header)

1 pilot jet size for every 3 main jet size increase

Add up all the jet size increases and subtract one. (Remember they go in steps of 2.5 for each jet size)

Under a mismatch condition, like individual filters and stock exhaust or 4 into 1 header with stock filter and air box, subtract an additional 1 jet size.

Check plug color often, sync carbs after each jet change, make sure the floats are set correctly, and seriously consider purchasing a Colour Tune. (See "Colortuning Carburetors" in the Maintenance Section).

Make sure your carbs are in perfect working order before making jet changes.

Example from my '79 XS1100 F:
Stock main jets: 137.5

Stock pilot jets: 42.5

2 sizes for 4:1 exhaust (Jardine)

1 size for single K&N

1 size for drilled air box

4 (main sizes) - 1 = 3 or 137.5 + (2.5 * 3) = 145.0
1 (pilot jet size) or 42.5 + (2.5 * 1) = 45.0

With this jet configuration I get 32-38 mpg on the open road, Smooth idle, very strong exceleration from off idle to 80+ mph, and steady pull past 120 mph. My "F" has 65K mile on it, of which I have put 33K with this jet configuration.

I have applied this to the '78-'79 carb set with great success. These guidelines should work for the '80-'81 carbs also. The only part I have not tested is pilot jet changing on the second generation carbs.

Happy Jetting

You might ask... "How do you pass an emissions test"?




Bout 140mph :woohoo:

No worries for me about emissions! I dont have any I have to pass in my area!!

So I found some issues with one of my Air screws and I ordered #20 pilot jets! So it will be the middle of the week before I can try again!

Thanks for the help so far! I will post some photos of the bike today, I hope you guys/gals enjoy them! I have to get it pin stripped still so there will be some updates soon!

Good looking bike

nice bike
I would consider going up to 29's with ur setup

Okay so I got it close to tuned! Just bumbed the Pilot up to a #20 and now its sounding a lot better! I'm still running rich though....maybe this is good for break in on the new motor? Any thoughts?

Whats the best place to start leaning it back out?

roll6285 wrote: Okay so I got it close to tuned! Just bumbed the Pilot up to a #20 and now its sounding a lot better! I'm still running rich though....maybe this is good for break in on the new motor? Any thoughts?

Whats the best place to start leaning it back out?

Wait for summer weather to fine tune it. If it's a tad rich but not fouling plugs, just ride it and get it broken in. Go after the carb tune after you've done the 500 mile service on it.

Okay summer is here and I have still been strugling to get these carbs from snorting and the exhaust back firing. It seems something still isnt right!

So....... New carbs?

What is the best option for me? Most importantly which one is going to be the easiest to tune?

Cr29? Cr31? rs34?

Any Thoughts will be great!

Read your plugs at your concerned rpm. Hold what ever rpm you want to varify richness for 5 mins. Kill engine and pull in clutch. Check the plugs. White-lean black - ritch. Light tan- perfect. Repeat this for 2500 rpm 5000 rpm 7000 rpm. That covers pilot needle and main.

roll6285 wrote: Okay summer is here and I have still been strugling to get these carbs from snorting and the exhaust back firing. It seems something still isnt right!

So....... New carbs?

What is the best option for me? Most importantly which one is going to be the easiest to tune?

Cr29? Cr31? rs34?

Any Thoughts will be great!

CRS29 Keihins would be he best choice. Around at 60 slow jet and 115 main jet should get you in the ball park.