Save your stock airboxes!!!

[Joe Nardy]

That is not entirely true. If the filter aera of a pod is less than the filter aera of the stock intake, you're going to be seeing more restriction. More restriction means less horsepower. Or the pods available for your bike have a very small filter aera. Case in point would be the pods availble from emgo and K&N for the 77-82 GS550's.

Joe, I'm only not a member of the pod crowd because I think you can get more filter aera with a simple airbox. More filter aera means less intake restriction... you know the rest. And for those not willing to fabricate, pods are the next best thing.

Greg,

The air filter area you have in an airbox may not be the limiting factor of air flow. The intake size could be the limiting factor. All the filter area in the world won't do any good if there isn't enough air available to take advantage of it. I have ridden my GS1100 with many different intake configurations over the years; stock airbox unmodified, stock airbox modified (top removed, top removed with additional holes drilled), with both stock and K&N replacement filters, and PODs. In all cases the bike was jetted accordingly. By far the strongest it has ever run is with PODs and K&N jet kit. It also starts and idles better than ever.

You can also fabricate all you want, you'll never have the engineering knowledge and testing capabilities of companies like K&N and Dynojet. I'm pretty sure you don't have a dyno, flow bench, sophisticated software, and years of high-performance tuning experience that these companies have. Sometimes it is better to let the experts do the research work for you.

Thanks,
Joe

[Billy Ricks]

It's not just filter area you need, it's airbox volume fed by clean air snorkeled in to have what's really needed. A set of K&Ns will deliver more than enough air and they have velocity stacks molded into them to boot. If you took a K&N apart and flattened out the pleated material you'd have far more filter surface area than it appears.

Like Joe I played with the stock airbox after going with a Kerker K2 and Dynojet kit early on. Trimmed the snorkel a little, removed the airbox lid, K&N replacement, you name it. The K&N pods worked best. I'm still using them with 34mm RS flatslides and they work fine with them as well.

If you're not willing to play with jetting leave the bike bone stock.

[Deesel]

Flywheels don't reciprocate. They revolve. Since the advent of inertial dynos people have been under the mistaken belief that reducing rotating weight makes more power. For instance changing from 30lb wheel to a 10lb wheel will make a bike "appear" to have more horsepower. While if you used a brake dyno, you would see no difference at all. The bike will accelerate faster due to less weight, and having to accelerate less flywheel weight. (add to that you actually end up accelerating rotating mass at least twice, it does make a big difference on acceleration)

By reducing the flywheel weight, you're effectively altering the weight that the dyno is using to measure against. For an inertial dyno to give you a readout of horsepower it has to know the weight that's being accelerated. Measuring the rate of acceleration you can then calculate how much energy is being put into the accelreating weight. The problem with these systems is that EVERY bit of rotating weight counts towards the "known" weight. And most people don't know what the weight of their tire, wheel, chain, transmission gears, and crankshaft weigh. If the weight is smaller, the horsepower will read higher because the dynos "known" weight has changed. This isn't to say the bike won't accelerate faster, beucase it will. The top speed will not have changed though, as the bike is actually producing exactly the same amount of horsepower.

Brake dyno's don't have this problem. They do have other problems though. This probally isn't the right palce to go into those though. Most dynos in use today are not brake dynos. And so the legend lives on.

That is not entirely true. If the filter aera of a pod is less than the filter aera of the stock intake, you're going to be seeing more restriction. More restriction means less horsepower. Or the pods available for your bike have a very small filter aera. Case in point would be the pods availble from emgo and K&N for the 77-82 GS550's.

Horsepower is a function of torque and acceleration. I have removed almost three ounces off of the flywheel of two different dragrace snowmobile engines of mine. Both made more horsepower on the dyno. One went from 211hp at 9400 and 108ft.lbs torque to 215hp at 9400rpms- same torque. My other engine made 198hp/ 100ft.lbs, went to 204hp/ 100ft.lbs. Both engines also made more horsepower earlier in the powerband. Both engines were dynoed on the same day (back to back pulls after changing magnetos) with no other changes(at that point) on an inertia dyno. I did this comparison delibirately because someone told me the same thing you say. My sled is consistantly quicker on the timers with the liteweight magneto. I have also seen guys build connecting rods and crankshafts out of titanium instead of steel for substantial gains in horsepower and performance. The bottom line is output at the end of the crankshaft will increase with lower "rotating" mass.
So until someone can prove my dyno experience wrong- I say your wrong if you think a lighter crankshaft assembly wont increase horsepower and performance.

I will admit I have never bothered to look at 77-82 550. But every GS I have seen had basically the same crappy airbox that pretty much any kind of pods could out flow.

[Nerobro]

Lots of stuff

I agree. I own a dynojet kit for my 55/65. And from what I can gather from you, other riders, and the racing community, the K&N pods for the GS1100's are big enough to not be a signi*@%^$*@%^$*@%^$ant restriction.

Horsepower is a function of torque and acceleration.

Horsepower is a fuction of work over time. There is no acceleration component to horsepower.

I have removed almost three ounces off of the flywheel.... bigger dyno numbers

Did you read what I typed? I said that by reducing flywheel weight you will make an inertial dyno show bigger numbers.

I did this comparison delibirately because someone told me the same thing you say. My sled is consistantly quicker on the timers with the liteweight magneto.

And I also said the bike would accelerate quicker. However it is NOT making more power. This "may" not be true on a 2 stroke as altering the shape of the crankshaft can have big effects on breathing, and I don't know what you did to lighten your crankshaft.

The bottom line is output at the end of the crankshaft will increase with lower "rotating" mass.
So until someone can prove my dyno experience wrong- I say your wrong if you think a lighter crankshaft assembly wont increase horsepower and performance.

The problem is you used an inertial dyno. Which means you will SEE a performance increse on an inertial dyno by reducing flywheel weight. I don't see how going to a dyno twice and changing flywheel weight and seeing the difference I said you'd see means I'm wrong. The information you just quoted, proves my point.

Yes, you accelerate faster. No, you don't make any more power. If you need an example of where the difference matters, there are two examples I can think of. Climing a hill is about power, If you're at full throttle climbing a hill, two motors that put out the same horsepower on a brake dyno will climb at exactly the same speed. (I should do the calculations on this, the numbers will be suprizing..) If one motor has half the flywheel weight, it will appear to be a MUCH stronger motor on an intertial dyno, yet it still will only make 50hp.

The other example is top speed. At top speed you're not "really" accelerating. As rate of acceleration slows, weight of rotating components means less and less. Eventualy reaching "it doesn't matter" status.

Or, if you need another example. An intertial dyno is essentially a drag race. The intertial dyno knows how much the car weighs, measures how long it takes your to push it up to speed, and from that determines horsepower. If you cut half the weight off, and don't tell the computer that, it will think you've got twice as much horsepower. You can test this with any online drag race calculator you like. Or a high school physics book.

Without a brake dyno you really can't get an accurate measure of your engines performance. Inertial dynos are great, they're cheap, they make the run very quickly, and they're very consistant. That's to say if you do two back to back runs, you're very likely to get the exact same readings both times. That's a good thing! However because the weight of your driveline is an unknown the dynos software has to guess at that number. Which means that if you change the weight of anything in the driveline, you'll see different numbers. That isn't true with a brake dyno.

I will admit I have never bothered to look at 77-82 550. But every GS I have seen had basically the same crappy airbox that pretty much any kind of pods could out flow.

Don't. The design still makes me sick to my stomach. The 83-86 airboxes are much much better. And in my case, there isn't much room to make things any better. There isn't really even room for decent pods!

[cafe850]

If anyone is till reading this post.

Yeah, it's a total pain in the a$$ unless you get the stage 3 Dyno Jet kit. Once you're dialed in you'll ditch that restrictive stock box. Way, way more performance with KnN pods and Dyno Jet. Be prepared to pay though. The only bummer of having a 4 banger. Twice the price. I did the conversion with my GS850 and I'm still running stock pipes. There are 3 sets of jets. When I upgrade the pipes I'll put the 170's in.

[SqDancerLynn1]

If anyone is till reading this post.

Yeah, it's a total pain in the a$$ unless you get the stage 3 Dyno Jet kit. Once you're dialed in you'll ditch that restrictive stock box. Way, way more performance with KnN pods and Dyno Jet. Be prepared to pay though. The only bummer of having a 4 banger. Twice the price. I did the conversion with my GS850 and I'm still running stock pipes. There are 3 sets of jets. When I upgrade the pipes I'll put the 170's in.

Dyno jet 170's has no relation to Muni jets sizes
Good pods $100
Dyno jet kit $150
Pipe $400
I have better things to spend $600-700 on

[Joe Nardy]

Dyno jet 170's has no relation to Muni jets sizes
Good pods $100
Dyno jet kit $150
Pipe $400
I have better things to spend $600-700 on

Having better things to spend your money on is a personal choice.

Performance-wise you'd be very hard pressed to realize such a significant horsepower increase for less money.

BTW, I got my K&N PODs years ago for $60, my Supertrapp stainless system years ago for $279 and my jet kit a few years back when they were on sale for $40. So for under $400 the performance bang-for-the-buck factor is even higher.

Thanks,
Joe

[BadBillyB]

Heres some info compliments of A.Graham Bell


Suzuki 1000/4V dyno test (stock motor)

RPM Test 1(hp) Test 2(hp) Test 3(hp) Test 4(hp) Test 5(hp)
3500 32.2 ---- ---- 29.1 30.5
4000 38.7 28.7 ---- 34.9 37.2
4500 43.3 36.2 30.8 39.7 43.4
5000 50.4 43.3 39.9 46.3 50.1
5500 56.0 52.5 49.2 53.8 56.0
6000 61.8 60.3 57.5 61.2 61.9
6500 67.2 65.9 66.0 67.0 67.7
7000 70.5 70.2 73.4 71.7 72.2
7500 73.9 74.1 76.6 76.8 77.4
8000 74.7 74.3 82.0 80.3 79.1
8500 71.4 73.9 77.3 75.5 74.9
9000 65.8 67.4 74.5 72.6 70.7

Test 1---stock 26mm carbs with air filter and air box connected
Test 2---29mm smoothbores with air filter and air box connected
Test 3---29 smoothbores with air filters and air box removed
Test 4---stock 26mm carbs with air filter and air box removed
Test 5---stock 26mm carbs with four K&N air filters fitted

note: in test 2 and 3 some figures were omitted as the dyno would not hold a steady load below 4500 with the 29 smoothbores fitted. Something to do with the 29's being a racing type carb and the low speed circuits are limited in performance.

Compliments to A Graham Bell
Copied from his book "Performance Tuning in Theory and Practice"
"Four Strokes"

I beleive........BadBillyB

[cafe850]

Oh, yeah?

Dyno jet 170's has no relation to Muni jets sizes
Good pods $100
Dyno jet kit $150
Pipe $400
I have better things to spend $600-700 on

That's funny, because I have 165 mains from my dyno kit in there right now. Have you installed a dyno jet kit? What would you do to your bike with $700 if not to upgrade the performance? Or would you not spend it on your bike? Confused.

Signed Dyno jetted, KnN pod filtered GS850

[cafe850]

Mikuni and Dyno Jet sizes

Numbers in the left side are Mikuni Jet sizes, the left is Dynojet and how they relate. Can you see the number 170 in the Dynojet side? I do. I have have 4 of them in a little baggy that came of a Dynojet state 3 kit.

Mikuni Dynojet 140 149.3
Flow rates based on size markings of Mikuni and DynoJet jets are not comparable. As a guide .. the chart to the left indicates equivalent sizes based on the diameter of hole in the jet. Mikuni jets are chamfered on the inside opening at the threaded end and
Dynojets have a machined flat surface. Keep this in mind when using this chart. These physical differences will never allow an exact comparison.
This chart is intended to be used as a tool to assist you in making a more
accurate decision when selecting a jet size range or comparing tuning data where an opposing brand is being used.
Actual jet sizes are highlighted with a gray background.
DynoJet jets are marked according to the diameter of the hole in the
jet .. ie: DJ150 = 1.5mm and DJ175 = 1.75mm. This is not true for Mikuni or most other OEM equivalent jets. This size
Mikuni jet, (N102.221 Super BN), is marked according to its' flow rate,
ie: 150 = a rating of 150 cc of fuel per minute.

150 142.5 152.0 145 154.7 155 147.5 157.3 150 160 152.5 162.7 165 155 165.3 157.5 168.0 170 160 170.7 162.5 173.3 175 165 176.0 167.5 178.7 180 170 181.3 172.5 184.0 185 175 186.7 177.5 189.3 190 180 192.0 182.5 194.7 195 185 197.3 187.5 200 190 202.7

[cafe850]

Mikuni and Dyno Jet sizes

Numbers in the left side are Mikuni Jet sizes, the right. is Dynojet and how they relate. Can you see the number 170 in the Dynojet side? I do. I have have 4 of them in a little baggy that came out of a Dynojet state 3 kit.

(after seeing this posted. The bottom row is Mikuni and Top row is Dynojet...it pasted weird)

Mikuni Dynojet 140 149.3
Flow rates based on size markings of Mikuni and DynoJet jets are not comparable. As a guide .. the chart to the left indicates equivalent sizes based on the diameter of hole in the jet. Mikuni jets are chamfered on the inside opening at the threaded end and
Dynojets have a machined flat surface. Keep this in mind when using this chart. These physical differences will never allow an exact comparison.
This chart is intended to be used as a tool to assist you in making a more
accurate decision when selecting a jet size range or comparing tuning data where an opposing brand is being used.
Actual jet sizes are highlighted with a gray background.
DynoJet jets are marked according to the diameter of the hole in the
jet .. ie: DJ150 = 1.5mm and DJ175 = 1.75mm. This is not true for Mikuni or most other OEM equivalent jets. This size
Mikuni jet, (N102.221 Super BN), is marked according to its' flow rate,
ie: 150 = a rating of 150 cc of fuel per minute.

150 142.5 152.0 145 154.7 155 147.5 157.3 150 160 152.5 162.7 165 155 165.3 157.5 168.0 170 160 170.7 162.5 173.3 175 165 176.0 167.5 178.7 180 170 181.3 172.5 184.0 185 175 186.7 177.5 189.3 190 180 192.0 182.5 194.7 195 185 197.3 187.5 200 190 202.7

[tkent02]

Has anyone found this Mikuni - Dynojet comparison available in sizes that apply.....

to our bikes? Don't think any Suzuki bikes use jets this big, at least not the VM series carbs.

[cafe850]

Your answer once and for all. Photo Proof.

I stand corrected on one issue. I opened my Dyno jet kit. Turns out I'm running 160 and I will be installing the 165's when I get the new pipes none the less, there is a 170 and you can run a 170 in a mikuni carb and obviously a 165 as you can see. It's been a year since I did the jetting, after all the sizes I tried, no wonder I forgot exactly what was in there but I was close. The little baggies at the top are my many failed attempts at using stock mikuni type jets from WPS. the little baggies below are the Dyno jet jets. Please note. DJ 165. Dynojet jets made all the difference. Please, I don't want to hear anyone else telling me these jets don't exist or work in stock SUZUKI mikuni carbs unless you are from another planet.[IMG]file:///H:/DCIM/100CANON/IMG_0268.JPG[/IMG][IMG]file:///H:/DCIM/100CANON/IMG_0269.JPG[/IMG]

[49er]

Heres some info compliments of A.Graham Bell


Suzuki 1000/4V dyno test (stock motor)

RPM Test 1(hp) Test 2(hp) Test 3(hp) Test 4(hp) Test 5(hp)
3500 32.2 ---- ---- 29.1 30.5
4000 38.7 28.7 ---- 34.9 37.2
4500 43.3 36.2 30.8 39.7 43.4
5000 50.4 43.3 39.9 46.3 50.1
5500 56.0 52.5 49.2 53.8 56.0
6000 61.8 60.3 57.5 61.2 61.9
6500 67.2 65.9 66.0 67.0 67.7
7000 70.5 70.2 73.4 71.7 72.2
7500 73.9 74.1 76.6 76.8 77.4
8000 74.7 74.3 82.0 80.3 79.1
8500 71.4 73.9 77.3 75.5 74.9
9000 65.8 67.4 74.5 72.6 70.7

Test 1---stock 26mm carbs with air filter and air box connected
Test 2---29mm smoothbores with air filter and air box connected
Test 3---29 smoothbores with air filters and air box removed
Test 4---stock 26mm carbs with air filter and air box removed
Test 5---stock 26mm carbs with four K&N air filters fitted

note: in test 2 and 3 some figures were omitted as the dyno would not hold a steady load below 4500 with the 29 smoothbores fitted. Something to do with the 29's being a racing type carb and the low speed circuits are limited in performance.

Compliments to A Graham Bell
Copied from his book "Performance Tuning in Theory and Practice"
"Four Strokes"

I beleive........BadBillyB

Thanks for this info BadBilly B.
Seems like the K&N pods are superior from 6000-9000rpm, but a little inferior down low. I was surprised to see that the 26's without airbox and filters(test 4) out performed the K&N's up top, mainly because the K&N's are fitted with velocity stacks internally. Do you know whether the carbs had the suzuki velocity stacks fitted in test 4?
If not, the shorter tuned lenth and no filter restriction must have made the difference.
Cheers
Ian

[redscott33]

What size jets.

Boy, am I glad to hear that someone is having success with pods on the Katana!!! Everything I have been reading is negative and I've got a set of pods coming in the mail so I was getting a bit disheartened.
I'll be running pods on a flat slide carb with a four into one system. Its the Kat1000 which is supposed to have bigger exhaust valves so I dont know if thats going to stuff up my next question. I'm after jet sizes for a similar senario of someone elses bike. Is there anyone out there that can give me an idea on what jet sizez I should be going for.
Thanks in advance,
Scott.