Opening up airbox?

From what I've heard about the the "drilling" of the KZ750R/KZ750E air box is the opening up of the drain hole on the bottom of the box which is still inside the the air filter. There is also the base support of the filter if you also figure out if there is a filter that makes up the difference of length and will seal you'll also increase inflow by taking it out. These are the mods I've thought about doing to mine BTW but haven't gotten to it. I did put 132.5 jets in it because of the ZR7 4-1 I installed. The needles are second from the top right now and I'm thinking of dropping them to the last notch. If I drill or otherwise increase intake flow I'll probably have to lift them again.

I've been reading this thread with interest. Recently, I was put onto another thread here about a CSR resto-mod-ELR kinda' thing which is an awesome read with lots of pics.
HOWEVER
The builder who has much experience with KZs gets into CV carb rejetting for performance AND he relates his experiences with results of each change he makes. This is, I admit, on a 1000 bike but I believe that Otto (the builder) demonstrates really valid points in his experiences to increase the performance of CV carbs.
You may want to read this thread as it will give you a greater understanding of the cause and effect of air flow, vacuum, jetting and such as it directly applies. [ CV carb information starts on this page ] but the whole thread is great if you have a few hours - 28 pages, start to end.
HTH

Check out Making power with air in tech tips,u will find a air box mod there.I did this mod and works great.I have mukuni bs34 carbs on my 83 l3 same as gpz750.I have 120 main jets in now anb it'd little rich.

G-Force wrote: Check out Making power with air in tech tips,u will find a air box mod there.I did this mod and works great.I have mukuni bs34 carbs on my 83 l3 same as gpz750.I have 120 main jets in now anb it'd little rich.

This is the one I'm sure I've heard most about.

650ed wrote:

[b]Nebr_Rex[/b] wrote: 650ed wrote: Drilling holes in the airbox is a mistake!!! Consider the fact that air is drawn into the airbox through the cap and then passes through the filter on the way to the carbs. If you drill holes in the airbox the air that passes through the holes will not be filtered at all, so dust, grit, etc. will be sucked directly into the cylinders and will accelerate wear. This is a bad thing for sure.

Nebr_Rex wrote: B.S. All depends on the design of the air box. More of the unknowing misleading the uninformed.
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YOU are the unknowing misleading the uninformed! Before you call BS take a look at the design of the airbox on the GPZ 750. If you drill a hole in the airbox air WILL come in through it and that air WILL NOT pass through the filter. You only need to look at the design of the airbox and you will see that I am correct and you are wrong, so don't be calling BS until you know the facts! Below is a diagram of the 1982 GPZ750 -R1 airbox. Notice the part marked #11012. That is the cap, and that is where the air enters the airbox. Now notice the part marked #11013. That is the air filter element through which the air passes and is filtered. Now notice the parts simply marked "A". That is the airbox. If you drill a hole in it the air passing through that hole will NOT pass through the filer element. Instead, it will be sucked through the boots marked #14073 and will pass directly into and through the carbs and into the combustion chamber, and as I stated dust, grit, etc... will be sucked directly into the cylinders and will accelerate wear. No BS! Ed

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I cut my teeth on KZ650d's, KZ650b's and KZ750h's. I know what the airbox looks like on those models. You seem to not understand my post. What others have posted on this thread should shine some light on the subject. When it come to this topic you always seem to get up on your high horse and be the high and mighty/my way or the highway commentator. And why do people edit there post? I try to proofread my stuff before I put it out there.


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Nebr_Rex wrote: And why do people edit there post? I try to proofread my stuff before I put it out there.

"There" :dry:

Nebr_Rex wrote: I cut my teeth on KZ650d's, KZ650b's and KZ750h's. I know what the airbox looks like on those models. You seem to not understand my post. What others have posted on this thread should shine some light on the subject. When it come to this topic you always seem to get up on your high horse and be the high and mighty/my way or the highway commentator. And why do people edit there post? I try to proofread my stuff before I put it out there.
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I did not understand your post, and I still don't. If you "cut your teeth" on KZ650 and KZ750 bikes and know what their airboxes look like you should have understood that everything I stated in my posting is completely true and that I was giving good advise. Even though everything I stated was absolutely true you stated that my posting was BS and added the remark that "More of the unknowing misleading the uninformed." I truly do not understand why you would call my posting BS and attack me when all the things I stated are true.

I had stated 3 things and all 3 are absolutely true -

1. Drilling holes in the airbox would permit unfiltered air along with grit etc. to enter the carbs.
2. If he wanted to permit more air to pass through the filter he could modify the cap and its tube, but he would be wise to do that on a spare cap in case it hurt performance.
3. CV carbs are very sensitive to changes in airflow.

So no, I do not understand your posting since it is bogus. I pointed that out because anyone reading your post might be confused. It doesn't matter if you consider my pointing that out to be getting on my "high horse" or believe I have a "my way or the highway" attitude. The facts are the facts whether you want to accept them or not. If you still believe any of the statements I made to be BS PLEASE explain where I am wrong. Again, the facts are the facts, so if you have more accurate information please post it rather than simply making nasty comments. Ed

Pods can be difficult to tune with VM carbs and with CV carbs even more so. They have their disadvantages. That's why I went back to the air box and have since the late 80's. A lot of the questions here involve a bike with no air box so the new owner is stuck with the pods the PO installed, then sold the bike. Others want to install pods because they look cool and are rumored to be a HP mod.
The advice given to keep the box is good. That will avoid all the adjustments needed to make them work on the bike. To a new owner, that could be the cause of frustration and the sale of the bike. Not everyone has the experience, time and money to invest on something that will give little or no gain in performance and in some cases cost it.
I have a right to my opinion as do the ones that don't agree with me. Calling it BS is out of line and uncalled for. It's just another opinion.
That's what is usually asked for. OPINIONS
Steve

You can safely modify the air box to increase airflow. Add these to the sides of the box near the filter:



Modify the intake tube by adding a few more holes and shortening a little. Add the hole to the bottom of the box under the filter.

Remember a few things. Kawasaki designed the air box to not only flow an adequate amount of air for a stock engine, but also to keep intake air noise to a minimum. This requires a sacrifice in air flow. So no, the air box is not designed for optimum air flow but rather a balance between flow and noise reduction. If intake noise is of no concern, then flow can be improved.

Despite what many think, CV carbs do not require a restrictive air intake to operate. The diaphram works because of a pressure differential caused by the VELOCITY of the incoming air. Pods suck because they kill velocity. Look at the factory air box boots. They are velocity stacks. As long as intake velocity is maintained, CV carbs will function. Correct jetting is a whole other topic.

Got a link to them?
Steve

www.amazon.com/Uni-Filter-UFV-6-Foam-Filtered/dp/B0022ZN76K

They are UNI brand filters, but the UNI website does not seem to be working for me at this time.

There's an area below the boots a couple could fit in. Be fun to try.
Steve