Fine Tuning Kz650

bountyhunter wrote:

I notice in your tag line it says:

"with pods "

The symptoms are:

"As they are now, I've got a decent bottom end, flat from about 2500 to 4500, alive from 4500 to 7500, and gutless from 7500 on."

This part sounds like the main jets are off:

"gutless from 7500 on."


This part:

"flat from about 2500 to 4500, alive from 4500 to 7500,"

Sounds like the needle taper is wrong or the needles are in the wrong place.

With pods, you can make engine tuning your life's work. The jet sizes and needle taper sre dialed in by the maker to match the flow characteristics across the RPM band. Changing to pods changes the flow characteristics.

That sounds reasonable with what is going on. I'll check the needles to see which ones they are for sure and also order some larger mains.

It is odd because at about 80mph at WOT I'm at about 6-7k RPMs and the bike then creaps the rest of the way to 86-90 and I run out of road before it can ever creep any higher. I am not as worried about top speed as I am about reaching it quickly for passing if needed. Tried to pass a pickup and they accelerated and kept pace till I topped out. Kinda sad that a 15 year old pickup can keep up with a bike, even a 30 year old one.

As was mentioned it would be nice to know what pilots, mains, etc your running. I'm not a pod person but they can work well with some patient tuning, I run a K&N in stock box. Let us know what jets, etc your running and we can help you better. Do you live at altitude?

"flat from about 2500 to 4500, alive from 4500 to 7500" sounds like part of the problem I was having. See "Stock specs screwing me up" in carb section.

Sorry, my carb info is in my signature (which now needs updated).

I found a decent condition, well priced, aftermarket 4-1 and muffler. Put it on, upped my mains to 112.5, pilots to 22.5 and left the needle alone. For the first time I broke 90mph on my bike. With more room and time I might have gone for the gold.

As it is now when I open the throttle wide while the engine is still building up I get a crackly sound from the engine. I seem to have decent power, but it may be too rich. I am not sure as I haven't had this behavior out of my engine before. It is usually when I have it WOT or almost there while still accelerating. I may need to practice good throttle control, but wondering if it may be something else.

Thanks for the help so far.

Holy cow those are HUGE pilot jets!!! Are you SURE that you don't have a gummed up passage in one or more of the carbs? When running K&N pods and no baffle 4-1 I never had to go over a 17.5 pilot...

anarki650 wrote:

Holy cow those are HUGE pilot jets!!! Are you SURE that you don't have a gummed up passage in one or more of the carbs? When running K&N pods and no baffle 4-1 I never had to go over a 17.5 pilot...

Thats what I was thinking as well, but that is what it takes. The carbs are clean, I've blown air through, soaked them and cleaned them, cleaner spray, checked all of the jets when they came off. Nothing blocking them or causing trouble. I may need to back the main jet off a step, but that is what I was trying to find out.

What about your petcock? Are you getting enough fuel delivered into the carb bank? Forgive me if you already talked about that, I'm feeling lazy today and didn't want to re-read the entire thread...

I'll make it simple. Its either the carbs or a roving gremlin who changes locations faster than I can troubleshoot. Not to be short, but I've checked and eliminated mechanical and electrical. Symptoms only appear and disappear with changes that effect the jetting. In this case, swapping exhausts and rejetting has gone from a flat mid-range to a kinda crack sputter that starts almost precisely at 5100 rpm's.

After a good long ride today, I think I'm going to drop the mains a size, try it tomorrow, and possibly move the needle. Also going to turn the air screws in 1/2 turn as the idle is a little rough, but the power at the bottom is good.

take some duct tape and start out wraping your air filters with one wrap and take it for a ride if it works better the jetting is lean if it works worse the jetting is rich.