Need help with engine tuning procedure on KZ1000R2

[tommyboah]

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 hmy:

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.

 

[Bozz]

If it runs at all, set the timing with a strobe light first. (draft a friend to be the throttle hand)
Rev it past the ignition advance point and set the full advance if you need to, with a Dyna it shouldn't matter much which mark you set it to as the advance is pre-set, just make sure you set it to the right mark for the RPM...


It will be much harder to tune the carbs with a mis-timed spark.


Once you are reasonably sure the ignition advance is close, then start on the carbs.
To do this "right" you need a way to accurately synch the carbs as well as check the mixture, where an electronic exhaust probe is preferred.
Most folks don't have one of these and you should probably at least consider trying to find a shop that has both the device and a person who knows how to use it well.


In the absence of an O2 sensor probe, you can get pretty close by reading the plugs, but it is a MUCH slower process.


Best of luck, and share some pics!

 

[tommyboah]

I had the Mikuni RSs of the bike and check the floats, seemed to be pretty much spot on 17mm, and also the bench synch seemed to be good straight out of the factory. i guess they do bench synch them at the factory before sending them out?

Okay, so I have the bike running, but not good. I thought I'd just check the compression before i started working more on the carbs and I got myself a small surprise. They were all out of whack, reading 117, 97, 80 and 93. F#¤%! :blink:

I thought I had done a good job on the head and all.

My pistons are brand new and have been installed by a machine shop so I figure they should be ok. I will try the oil in the spark hole method to rule out a leak from the pistons.

The valves have also been changed, so there could be a leak there? I thought I did a pretty good job shimming them, but maybe they sink in a bit when breaking in after a valve job, so they don't seal as well now after the engine has been running? does this seem plausible?

Could it be the springs? They have never been changed as far as I know, and now I am running GPZ1100 cams. Maybe they need some stiffer springs?

Any tips on how I should proceed to troubleshoot?

 

[Bozz]

I'd start by retorqueing the head (after a few heat cycles they can settle a smidge)


Then re-do the valve adjustment very carefully.


Then do another compression test with a known good tester (some cheap harbor freight testers are known to be unreliable)


Then do a leakdown test and see if you are loosing at the valves or rings.


All this being said I would suspect the valve adjustment the most, as it is really easy to miss something in that procedure.


Relax, take your time and be thorough.


Chances are it's something relatively small and fixable.

Only after you have compression close across all cyl's should you vacuum synch the carbs and adjust mixture, so don't focus on the carbs right now, get your valves and compression correct first.


Cheers!