Suzuki GR650 - back to work...

Re: Suzuki GR650- change is in the airBOX.......

Ha! Thank you sir. I was blown away when I first saw your intake/exhaust setup. So yes, chalk and cheese......I'm not 100% sure I'll be able to swing the full fairing this year. I ordered a slick little quarter fairing for now. We'll see how that goes.......

I did get the carbs painted and installed the new jets yesterday but didn't take any pics. I was tired, and ran into a throttle cable issue and just went to bed. Next time I'm in the garage I'll snap a few.....
 
Re: Suzuki GR650- change is in the airBOX.......

Oops- forgot to update this. Got the new box to hold water (although there are a few spots that "weep" a little). So I pulled a stock airbox out and got some measurements. Some details first though: I removed both air filters, Saran Wrap was clamped around the carb mounts, and each box was filled and measured a few times to get a consistent measurement. Here's what I ended up with:

Stock box: about 3700 ml
New box: about 4100 ml

But here's my concern: the stock GR air filter is shaped like a Twinkie and basically cups the carb openings. The GS500 filter is cylinder shaped and is fairly larger (physically and has more surface area) so I'm really hoping that the displacement of the GS filter doesn't affect the internal volume of the box.

Anybody have an idea?
 
Re: Suzuki GR650- change is in the airBOX.......

Scratchs head and shruggs.

Wouldn't the GS filter flow more and therefore reduce the need for a larger airbox?Just tossing out thoughts.I know the air box is just a buffer and the only real restriction is the filter.I am considering opening up a GS500 air box where the stock filter mounts,and mounting a high flow shallow pleated filter over it.My theory is,getting the filter out of the box,will allow more air in the box, without as much restriction,and a shallow flat pleated filter will allow a more direct path for the airflow.Remember that the GS500 box was built for emission and is a restriction.How much on a lower reving GR,I don't know.Maybe an upgrade.Just my thought and maybe wrong.

Here is a possible filter I would like to use. http://store.knfilters.com/search/product.aspx?Prod=33-2291
K&N 33-2291 Product Specifications
Product Style: Panel Air Filter
Height: 0.938 in (24 mm)
Outside Length: 7.688 in (195 mm)
Outside Width: 6.125 in (156 mm)
Filter Material: Cotton Gauze
33-2291.jpg
 
Re: Suzuki GR650- change is in the airBOX.......

I thought about using a flat filter like that, but trying to mount it securely was my biggest concern. A guy on the twins site had a pic of a stock filter sitting next to a GSX1400 (?) filter and the only difference was the 1400 filter was 1/2" longer. Same material, diameter, mounts, etc. So I would like to believe the 500 filter could pass more than enough air. Now that I think about it, the filter shouldn't make a difference if it's mounted internally or externally.......I mean, it's either entering the box and being filtered OR being filtered then entering the box. Does that make sense?

The only info I could find online dealt with the noise suppression of an airbox and resonating frequencies. While a tuned box definitely effects performance, I'm curious if I did upgrade my intake at all........maybe I'll check the actual volume the GS filter displaces before I truly worry too much.
 
Re: Suzuki GR650- change is in the airBOX.......

Spray the inside with Flex Seal if it leaks.

That's about all I can contribute at this point. When I come into this thread lately all I get is airbox, science, science, science, kick ass photo, science, science, science.
 
Re: Suzuki GR650- change is in the airBOX.......

I was thinking about that too - but there's always that hint of gas inside a box. So whatever I use, I don't want it breaking down and getting sucked in.......

And I'll be happy once I can put the bike on the road and make sure everything works. I'm just some guy sticking crap together, ya know?
 
Re: Suzuki GR650- change is in the airBOX.......

Heck Rich, as long as you are at it, you ought to try to tune the box. There are big gains to be had there, same as with a pipe. The theory is all on the internets, just waiting to be picked. I'm really digging you ingenuity here!
 
Re: Suzuki GR650- change is in the airBOX.......

No doubt - I found a cool site late this morning with all the formulas for a "proper" box. But I worked all night so any kind of algebra is out of the question......

If I can get it close, I'll be happy. I mean, this isn't a "real" race bike so if it revs clean through the gears it will do it for me. We'll see what happens.
 
Re: Suzuki GR650- change is in the airBOX.......

Rich, nice thinking there wit that still air box/plenum chamber.

IIRC to work well the box needs a volume to 2 times engine size which you have. It needs bell mouths/velocity stacks on the carbs into the airbox. It needs a large enough intake to the air filter and a large enough filter. It's better to avoid flat surfaces directly behind the carbs so that the reversion pulses are not reflected back in and it also avoids other reflections into the carbs

You seem to have most of that covered. Try to avoid large flat surfaces - they resonate and pulse. You can add ribs on the inside if necessary. Don't forget a drain plug to allow water or fuel to escape. I'll try to find the reference to box volume later today.

Great idea nicely implemented. After the road tests do we get to see the carbon fiber lightweight final product. ;-)
 
Re: Suzuki GR650- change is in the airBOX.......

I feel that removing the air box on my GS made the torque curve move up the rpm level,but that could be due to all the other changes I made.
 
Re: Suzuki GR650- change is in the airBOX.......

Thank you Teazer! I really do appreciate your feedback!

I ordered some velocity stacks from DCC, so I will see what I can do to implement them. The air filter is almost directly behind the carb ports, so any resonance should deflect off the round shape of the filter. And since the entire box is plastic, I can use the soldering iron to burn "channels" into the interior walls. I will most certainly look into some type of drain as well.

Carbon fiber, huh? I might know a guy.........:D. Most likely I'll be tuning/messing with the current box all season though. Maybe next winter.
 
Re: Suzuki GR650- change is in the airBOX.......

Rich - an airbox is definitely the way to go for reliable performance. I'm currently trying to figure out how to fit one in my frame along with everything else.

Some formulas would be handy so I would know if I'm headed in the right direction - could you give me a link to the site you found?

Crazy
 
Re: Suzuki GR650- change is in the airBOX.......

This is probably the best I've found:
http://motorcycleinfo.calsci.com/Airboxes.html

I haven't had the chance to decipher all the "geekinese" yet though! :D
 
Re: Suzuki GR650- change is in the airBOX.......

Thanks Rich - all information is useful, even if some takes more work to decipher!

Crazy
 
Re: Suzuki GR650- change is in the airBOX.......

As much as it pains me that seems fairly stripped down. He speaks of a snorkle as a tube in static terms, but every box I've torn up has a funnel to help combat 'friction stagnation'. How would that affect air flow and volume needs?
 
Re: Suzuki GR650- change is in the airBOX.......

Wish I had a good answer for that. But the original airbox had 2 snorkels - two rectangular rubber tubes for air intake. While there's no mention of funnels, I do know on subwoofer boxes a flared port reduces port turbulence (that flapping sound)
 
Re: Suzuki GR650- change is in the airBOX.......

The Yamaha RZ350 airbox has a rounded rectangular intake tube. It also narrows in taper from the outside to inside.
You would think that a combination of the greater wetted area of the rectangle and the corner vortices it creates would considerably restrict air flow. The taper would also provide resistance to airflow, while increasing its velocity.
We have to assume that the design engineers have reasons for these counter-intuitive aspects of airbox shape, but until we know what these reasons are we can console ourselves with the words of Gordon P. Blair and W. Melvin Cahoon in their paper on bellmouth design 'the general conclusion might be glibly stated that the design of an intake bellmouth is not as difficult nor as vital to good engine breathing as might have been imagined'.

Crazy
 
Re: Suzuki GR650- change is in the airBOX.......

According to an article by David Vizard, the best bell mouth improves flow by 5-6% and the worst cost about 2-3%. One might assume that teh effect on power is probably less than that, but it's all teh little changes that add up to the real difference.

I love the ones that Honda used to fit inside their airboxes on SOHC fours - and most companies still do the same. The boot from the airbox to carb usually has a nice flair inside the box. Ports generally should be shaped as a funnel to increase velocity Look at a modern airbox for ideas as to the intake snorkel shape. Typically they are a simple rectangular tube section and that works fine as long as it's large enough.
 
Re: Suzuki GR650- change is in the airBOX.......

Big Rich said:
This is probably the best I've found:
http://motorcycleinfo.calsci.com/Airboxes.html

I haven't had the chance to decipher all the "geekinese" yet though! :D
Click to expand...

Thanks for that link.


I wonder if I could fit velocity stacks inside of the GS box,if I go with a flat pleated filter.Maybe we should start a thread all about airboxes?
 
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