TOPIC:

fastidiots wrote: I have seen the bread boxes, but didn't really like the rectangle shape for my kz1000 project, I have a plan in mind for an oval shaped filter box that I will try to match to the stock carb settings. but later on when i get to rebuilding my kz750, I was thinking about going with pods and trying to tune the airflow to work with the stock carb settings. If, however, I can get the oval one for the 1000 to work right, I might just build a similar one for the 750.

I'm with you on the rectangle shape that's what started me on designing an oval one. For a long time I tried to find an oval replaceable filter that I could sandwich between 2 pieces of aluminum but could never fund one with the right dimensions to fit. If you get it done before I do please let me know. I have also heard the dual pods from K&N work well as the house 2 carbs in one filter.

I suspect what Boutyhunter meant was that might happen if you passed a truck at speed
(that was meant for Loudhv's comment)

Fringe jetting is what causes the majority of "problems" like this. Riders think they are jetted correctly when they are not.

What does fringe jetting mean?

bluezbike wrote: What does fringe jetting mean?

It's when fringe gets caught in the air intake.
But is easily avoided by sufficiently raised handlebars.





Good Fortune!

bluezbike wrote: What does fringe jetting mean?

Ah fringe jetting. This is a term that means basically what it sounds like. You have dialed in your bike to the point that it finally "runs right", but then any sort of change in elevation or air temp and it begins to run so-so again.

This is because your final jetting landed you on "the fringe" of the AFR window that you need to stay in, in order to run at the optimum level.

Due to fringe jetting situations, you can have a bike that runs well, but is still not jetted correctly. The majority of machines fall into this category, and thus the common opinion that "carbs are picky", or that they require constant fiddling to keep a machine in optimal running condition.

When you get off the fringe and into the middle of that window all the way through the RPM range, you will find that your machine is MUCH less affected by changes in its operating environment.

Tumbleweeds wrote: Fringe jetting is what causes the majority of "problems" like this. Riders think they are jetted correctly when they are not.

Yes, exactly right.

During testing, I had the carbs jetted on the fringe of lean. It seemed to run fine, but the wideband clearly showed the jetting was lean. Surprisingly, it ran fine even near 16:1 AFR under light cruising load. However, that is when gusts of wind etc. could bump it to 16.5:1, and you could feel some hesitation.

Seat of pants said the bike was jetted right for pods, but the wideband o2 told a different story. You will only notice this during light cruising, which is when you are typically at the leanest continuous running. (Closing the throttle and coasting will be leaner, but you will be slowing down,) During acceleration, the bike will be much richer and gusts and trucks won't affect the running.

Once jetted properly, gusts and trucks won't affect the running at light cruising either. I usually shoot for 14:1 at the leanest for light cruising (fully warmed up).

A wideband!? CHEATER!!!!

You understand exactly where I am coming from though.

Gusts of wind running over the filters will created pulses of both higher and lower pressure than ambient.

I have pods K&N pods and a 4 into 1 pipe on my 650 and it runs perfect. It took me awhile to get it tuned correctly but once there I have not touched them in decades. They are not effected my wind, temp rain or elevation.
You just need to spend the time in tuning.

Thanks for all the replies........this raises another question (and I hope this is not a thread snatch) what are the principles of using a wideband o2 , what is AFR and how does one use them to tune/jet carbs
At exactly 57 mph and at any speed over that I would lose a lot of power and it felt like carbs were running out of fuel or something....I recently took off the fairing you see in my avatar, I think it affected the airflow over the carbs and soon as I get it running again after the winter I will see what effect that had.

Patton, I am still laughing over your great comment and pic

bluezbike wrote: Thanks for all the replies........this raises another question (and I hope this is not a thread snatch) what are the principles of using a wideband o2 , what is AFR and how does one use them to tune/jet carbs
At exactly 57 mph and at any speed over that I would lose a lot of power and it felt like carbs were running out of fuel or something....I recently took off the fairing you see in my avatar, I think it affected the airflow over the carbs and soon as I get it running again after the winter I will see what effect that had.

Patton, I am still laughing over your great comment and pic

If you do an internet search for "air fuel ratio" and wideband o2 sensors you will get more reading material than you can shake a stick at.

I put K&N pods on my KZ1000-P7. The instructions that came with the pods said to increase the jetting 15% from standard jetting. Well that was my interpretation of them anyway. The instructions were rather confusing since they were trying to explain how to use the pods with all carbs on earth. I upped both the main and pilot jet to meet this instruction. Runs good. I checked the plugs to make sure the bike wasn't running rich or lean. The plugs look spot on. I did re sync the carbs when done with the jet mod. I also made a brace to support the back of the carb bodies to the frame. The instructions also said to do that.