Need help with engine tuning procedure on KZ1000R2

I've finally got my bike ready and it is firing, but running poorly on idle. I need to use the throttle to keep it running. I am trying to figure out a procedure for doing the adjustments, and to be honest I am not sure which end to focus on first.

The engine has been bored to 1075ccm and I've got GPZ1100 cams and new valves. The valves have been shimmed correctly. I have also got new carbs, Mikuni RS36 with K&N filters, along with Dyna-S ignition. Pretty much everything is different from stock :ohmy:

I have figured that I should focus on the idle running to begin with and I have these things to address, but I am not sure which order I should do them in. My suggested order is:

- Tune in the Mikuni RS carbs
- Tune the Dyna S ignition

I figured I should tune the carbs first in order to get it to run on idle by doing addressing the following:

- Carb idle mixture screw (pilot jet adjustment) I have found the procedure for this on the Mikuni tuning manual. Find the middle position between 1/2-3 turns on the screw
- Carb idle adjustment screw (how should I adjust this for a default position, and what exactly does it do? Is this just an offset for the idle throttle?)

How do I start adjusting the carbs, as I have to hold the throttle to keep the engine from dying? Do I need to do something with the idle adjustment screw first, before addressing the idle mixture?

Or do I have to do the ignition timing before I do the idle adjustment? Pretty hard to do this alone while having to hold the throttle :blink:

I appreciate any help, as I am pretty new to the art of engine tuning.

Thanks.

Assuming that the cam timing etc is correct you need to get the ignition timing sorted first as that could be the cause of it's reluctance to idle.
it's an easy job for one person.
Turn up the throttle stop screw to stop the engine from cutting out ,normal idle is around 1000 rpm.
You need a strobe to set each pair or cylinders at full advance at around 38 - 40 degrees.
It can be done static by hand without a strobe initially to get it near enough as the Dyna ign has such a strong spark but it needs some experience.
Once you have the timing sorted you need all the carbs set at a base line and then use vacuum gauges to balance them.
Unless something is wrong with the pilot circuit you should get it to idle easily no matter whether the pilots are too big or small..
Only after this is done can you start on fine tuning the fueling.
The only way to do this is with 1/4 -1/2 - 3/4 and full throttle plug chops if you don't have access to a dyno.

zed1015 wrote: Assuming that the cam timing etc is correct you need to get the ignition timing sorted first as that could be the cause of it's reluctance to idle.
it's an easy job for one person.
Turn up the throttle stop screw to stop the engine from cutting out ,normal idle is around 1000 rpm.
You need a strobe to set each pair or cylinders at full advance at around 38 - 40 degrees.
It can be done static by hand without a strobe initially to get it near enough as the Dyna ign has such a strong spark but it needs some experience.
Once you have the timing sorted you need all the carbs set at a base line and then use vacuum gauges to balance them.
Unless something is wrong with the pilot circuit you should get it to idle easily no matter whether the pilots are too big or small..
Only after this is done can you start on fine tuning the fueling.
The only way to do this is with 1/4 -1/2 - 3/4 and full throttle plug chops if you don't have access to a dyno.

Thanks for the input. The cam timing should be good. I set it according to the TDC mark with exhaust arrow pointing dead forward and inlet arrow dead backwards. 22 links in between like in the manual I will address the Dyna S ignition first. I have a strobe light, so I should be ok there. So far procedure will be:

1. Tune ignition with strobe
2. Synch. carbs with vacuum gauges
3. Adjiust jets on carbs (pilot mixture etc.)

Looking forward to messing around with this after work :woohoo:

I noticed that you mentioned going out 3-turns on the pilot fuel screw. I don't think this is the operating range for this circuit, and far exceeds the max turn for this screw.

I have not been able to find the documented operating range of the pilot fuel screw .

I think the intended operating range for the RS carbs is from closed to 1 turn max, then you need to move up a pilot jet to richen the circuit. BUT ...... the only mention In the manual says 1/4 to 1/2 turn ...... NOW does this mean that the operating range is just that.......out to 1/2 turn max. I have been trying to find out what the range is? but haven't found it yet.
_____________________________________________________

UPDATE:

I talked to Mikuni Tech Support on this issue. They said 1 - 1/2 turn max, if you need to go richer you need to move up a pilot jet.

He said that you can go past 1 turn but the spring tension that holds the pilot fuel screw in place becomes an issue ...... with vibration the screw can work loose, carbs fall out of sync or pilot fuel screw can fall out and become lost.

tommyboah wrote:

zed1015 wrote:
1. Tune ignition with strobe
2. Synch. carbs with vacuum gauges
3. Adjiust jets on carbs (pilot mixture etc.)

Looking forward to messing around with this after work :woohoo:

Tommy its easy to set the timing statically on the dyna the bike is not running for this. You can download a PDF HERE

Sound like you are on the right track.

Not sure how my post got tangled up in the quote

Tommy its easy to set the timing statically on the dyna the bike is not running for this. You can download a PDF HERE

Sound like you are on the right track.

kaw-a-holic wrote: Not sure how my post got tangled up in the quote

Tommy its easy to set the timing statically on the dyna the bike is not running for this. You can download a PDF HERE

Sound like you are on the right track.

Thanks Kaw-a-holic. I guess RTFM (read the fucking manual) applies to all types of electronic devices after all, not only PCs and consumer electronics

it will run but like zed and I told you before there to big for you set up

peter1958 wrote: it will run but like zed and I told you before there to big for you set up

I appreciate the warning I remember some of you said that, but some also say that it is a go. I don't have any other carbs for the bike, so they will have to do for now. Need to get me some road time on the bike

I have now properly set the ignition timing, it was off. Did it the static way with a test light/multimeter.

After this I tried firing it. Had to use the choke and grind it with it almost firing. Tried it for some while without luck. Fiddled with the idle adjustment screw giving more idle and then it fired reving high. Turned down the idle adjustment screw and got it running at around 1000 rpms according to the tacho. I then stopped it thinking that I had dialed in the starting. After that I was back to the same point I started, the bike almost firing but probably not getting enough fuel to fully fire.

Is this the idle mixture doing this. I will look at this later today to see if it helps.

I have now properly set the ignition timing, it was off. Did it the static way with a test light/multimeter.

After this I tried firing it. Had to use the choke and grind it with it almost firing. Tried it for some while without luck. Fiddled with the idle adjustment screw giving more idle and then it fired reving high. Turned down the idle adjustment screw and got it running at around 1000 rpms according to the tacho. I then stopped it thinking that I had dialed in the starting. After that I was back to the same point I started, the bike almost firing but probably not getting enough fuel to fully fire.

Is this the idle mixture doing this. I will look at this later today to see if it helps.

I got it running again now, think it was something do to with the fuel vacuum hose not feeding any fuel. I also checked the spark plugs for spark and managed to electrify myself :woohoo: powerful spark!

For info I got the RS36-D3-K, running 130 on the main jet, P-4 needle jet, 17.5 pilot jet.

Now I got it running ok in idle@500-600RPMs with idle mixture screw at 1 turn out. If I go lower turns on the idle mixture (should mean richer on fuel) it starts to slightly backfire or spit (not sure, it's not a big bang but sounds like a spit but coming from the exhaust i think). When reving in neutral above 1.500RPMs it will lock it self running around 1500-2000RPMs not wanting to fall down again.

i still havent synched the carbs yet, as I am thinking of taking them off and bench synching versus running. Could the carb synch be causing this whole thing?

When putting oil in, I noticed I have overfilled a tad, as I could not read the window inside my garage. I see it better in the sun light. I will take some out with a syringe as soon as it cools down a bit, too hot to remove now.

Any tips for me on the idle not wanting to go down from 1500-2000RPMs?