weather stations

[Luckystrike]

I'm fairly new to two stroke tuning and was wondering what most of you more experienced guys use for a weather station. I saw some at GP-City.com but the prices seem a bit on the high side. Thanks in advance.

[rodnex]

I guess the term 'weather station' implies one self contained unit that is capable of doing math calculations, kind of a mini computer. Hence, the cost.

An air density gauge, and a Radio Shack digital temperature and humidity gauge will get you the same results, at much less cost, but they will require a some thinking/math(ugh!) on your part.

The air density gauges are available for around $100, Kinsler and Longacre are two
that I've seen used at the track.

The link below explains jetting, and using temp.,humidity readings to determine air density, check it out.
http://users.oc-net.com/dgriffiths/jettingmadeeasy.html

Here's a link to a sample radio shack gauge: http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F007%5F024%5F002%5F000&product%5Fid=63%2D1032

Hope that helps.

Rod

[Luckystrike]

Rod,
exactly the answer I was looking for. Thanks a bunch!

[mtk]

I'd substitute a barometer for the "air density" gauge. Those things are as useless as tits on a bull, in my opinion, since they are totally arbitrary. Roadracing World did an article on them and the bottom line was that no two gauges read out the same. So, if you drop your gauge and damage it, you're screwed. All your notes are now worthless.

A barometer, on the other hand, only requires a call to the National Weather Service to recalibrate since most local offices have a barometer on the wall. Mine got dropped and when I got home I had it recalibrated in about 10 minutes. Note: Do not use the barometric pressure readings given on the weather forecast! These are corrected for local altitude (which is about the stupidest idea I've ever heard of myself, but that's the way it's done) and as such are meaningless on an absolute scale.

After you get the barometer, the first link posted above will get you to some instructions I wrote on how to calculate air density from barometric pressure, relative humidity, and temperature. That's all you need to know.

[Luckystrike]

Good thing since the Kinsler Air Density Gauge is $130. http://www.wera.com/ubb/biggrin.gif

[rodnex]

mtk,
you wrote that page? Is that your website?

either way, Nice work.

Thanks!
Rod

[Jack]

Jeeezus, now you gotta be a friggin meteorologist to race a motorcycle? What ever happened to jet it fat, take plug cuts, and adjust as necessary? You guys are putting too much science into a weekend at the track for an old fart like me. Never was much of a note taker, other than in the head. Then again, maybe that's why I've yet to put a 125 on the box? Lordy, next thing I'll need is on board telemetry. This IS club racing, ain't it?

Maybe I should give this stuff up again and get back to fishing. Then again, some of the crap in those bass boats make weather stations and telemetry sound like almost a bargain. I never knew you had to have sonar, radar, GPS, auto pilot sonar controlled trolling motors, color gauges, water temp gauge, and Hach water testing kits for fishing, either, 'til I started watching ESPN outdoors. Now days, a plastic worm and a Zebco 404 just won't do. It all just seems like a way for someone to make a buck, to me.

Jack

[mtk]

Rod,

It's not my page, I only wrote the stuff about calculating air density at the bottom of the page.

Jack,

You're looking at it all wrong. Jetting this way can help eliminate the unfortunate side effect of guessing on the wrong side of "jetting fat," i.e. the wicked highside when the bike siezes. http://www.wera.com/ubb/smile.gif Besides, you gotta spend that fish finder money on something, right?

[WERA773]

Originally posted by mtk:
I'd substitute a barometer for the "air density" gauge. Those things are as useless as tits on a bull, in my opinion, since they are totally arbitrary. Roadracing World did an article on them and the bottom line was that no two gauges read out the same. So, if you drop your gauge and damage it, you're screwed. All your notes are now worthless.



MTK has a couple of good points here. Without trying to debate the relative usefulness of bull tits, it's important to note that air density gauges do not read the same. This means that:

1. You should not just look at your pit-mate's gauge and use whatever jet he is using. Every gauge and every 125 are different.
2. Treat your air density gauge with care. Don't keep it out in the rain. Don't drop it. I think you get the point here.
3. Keep notes. Lots and lots of notes. Be as consistent as possible when you take your notes.
4. If you get a new bike or a new gauge, start from the settings in the manual and work from there.

I hope this helps. For the record, I use a longacre air density gauge and the thermometer/humidity gauge combo from radio shack. And, I havn't siezed my RS yet.

Aaron
1996 RS125
WERA 773 Expert

[mtk]

That's the problem though. If you drop the gauge (and let's face it, it can happen; no one plans on dropping a $100+ instrument) you're hosed. Utterly and totally hosed. You have no idea where your new gauge will read.

All you need to do is ponder this question: if your air density gauge reads 94%, that is 94% of what? Without knowing that baseline, you don't know squat. That's like me telling you the temp is 43 degrees. Is that C or F? Without the units, the number is meaningless.

A barometer gives you the exact same information, except it does it with units attached. 29.50 inHg (inches of Mercury) is the same anywhere on earth and the same on any gauge. And if you drop it, any local National Weather Service office has a barometer on the wall (a real mercury barometer) and they can tell you the uncorrected barometric pressure in minutes with just a phone call.

In fact, they can even tell you the corrections used for the local weather forecasts. Then, if you're really tricky, you can call the local offices in the towns where you race, get the corrections, and then uncorrect the local forecast data.

Then you can dial up the weather channel, uncorrect the barometer reading, read off the temp and humidity, and then calculate the air density without even being at the track. Now you can put the bike in the trailer with the right jetting to start with.

Try that with an air density gauge.

[Stu]

If you do have one of the fragile 'do not drop' things, how about getting a reading off someone elses less fragile kit, then if you do drop it, you can least check its reading next time you see them, so long as the weather conditions arent that far off!

[mtk]

Yeah, that will work. But personally, I don't like to rely on other folks. If he's not there or something, I'm SOL. That's why the barometer is so handy; the National Weather Service is always available and they have offices nationwide.

Honestly, an air density gauge IS a barometer, more or less. I don't know exactly how they work, but they have to be measuring barometric pressure as at least one of the components. The problem is the units they read out in. A percentage of an unknown quantity is a useless number if you can't secure the baseline it came from. With a barometer, the baseline can be reestablished anywhere in the USA with just a phone call. Of course, you have to be relatively close to the office to get a really accurate zero, but it's still loads easier than trying to reestablish a baseline for your air density gauge.

[Dave Parker]

MTK - Nice article dude! What did you do, stay at a Holiday Inn!! Personally I just jet my 400 by the amount of pain I am getting in my old torn up knees. More pain, larger jets! Seriously, I use an AD gage and the Radio Shack Temp/Humidity combo. I establish a "baseline" on a dyno, recording the data when I'm satisfied with the HP. Then I just "jet by the numbers" at the track. And I find that when I run things just a tad "fat" it helps on the long straights. Just my $.02

[mtk]

Nope, I stayed in Engineering School for about seven years and two degrees. http://www.wera.com/ubb/smile.gif

[rodnex]

mtk, any suggestions on a buying barometer?
* how much do they cost?
* are you sponsored by 1-800-CALL-ATT,(all those phone calls to the National Weather Service)?

You got a point, air density gauges may not be the 'safest' way to go.

what if...............?

you lose or break the gauge.


<begin rant>

Do we all really need or expect that level of security?

The only way to be 100% sure that nothing will ever happen to you, that you cannot completely recover from
is to do nothing. and that might not be completely true, either..


Let's see..., racing is FAR from the 'safest' sport around,
and things will get dropped, crashed, lost, stolen, borrowed, etc..
with no 'guarantee' of a complete recovery, what then?

Do we all carry spare everything and only go racing if our subscription
to Norton Backup for Racing(c) is up to date?
So we can race with the confidence that we will recover from our crashes and our bikes/bodies/spares kits will
be 100% safe?
(sorry for that last joke, it was a joke...really)

what if.................?

you read this and think i'm nuts


</end rant>

[This message has been edited by rodnex (edited 08-02-2001).]

[rodnex]

I found this link:
'How and Where to buy a weather station.'
http://www.weatherwatchers.org/wxstation/buy/

[mtk]

Barometers are about the same price as an air density gauge from what I've gathered. I don't have a source for them offhand since I already have one.

I've called the National Weather Service once, ever, after I dropped my barometer and screwed it up. That one phone call saved me countless hours of grief since it enabled me to still use my 2 years worth of jetting notes. Had it been an air density gauge, I'd have had to start over from scratch.

Hey, if you want to invest years of time and oceans of money in engine development around an air density gauge, go wild. Just be aware that when Mr. Murphy rears his ugly head (which he's won't to do, usually at the most inopportune time possible) he's going to screw you over and leave you without a pot to piss in.

Consider this scenario: You've worked all year and done reasonably well. The bike is dialed in, runs like a demon (when you've got your jetting dialed in, that is), and there's one race to go in the season. It's you against your arch-nemesis, Racer X, in a one-race shootout for the championship. The winner takes the championship, gets the girl, and all the money, fame, and recognition that goes along with it (OK, so I embellished it a bit, sue me http://www.wera.com/ubb/smile.gif ). As you're setting up your pit, you trip and send your gauge flying, bouncing across the pavement. When you pick it up, it's clearly reading differently than it did just 5 seconds ago.

Which gauge do you want that to be, now that 6 months of work and many thousands of dollars are hanging in the balance? One that can be fixed in 10 minutes or one that results in everything you've done to date being thrown in the trash?

With a barometer, you recalibrate it as I mentioned above, set your jetting, and then kick Racer X's ass for the championship. With an air density gauge, you take a guess at your jetting and hope the bike doesn't sieze.

I'll take Option A, thanks.

[CharlieM#90]

Originally posted by mtk:
Consider this scenario: you trip and send your gauge flying, bouncing across the pavement. When you pick it up, it's clearly reading differently... One that can be fixed in 10 minutes or one that results in everything you've done to date being thrown in the trash?

With a barometer, you recalibrate it as I mentioned above, set your jetting, and then kick Racer X's ass for the championship. With an air density gauge, you take a guess at your jetting and hope the bike doesn't sieze.

I'll take Option A, thanks.

Alternate scenario.......
You drop your barometer, sending it flying. It's clearly not reading what it was 10 minutes ago. No problem, you think, I'll just call the NWS. But, because you've told everyone else to do this, you can't get through 'cause the switchboard is overloaded.
Meanwhile, you hear "first call". And then think to yourself, "Duh, if only I hadn't relied soley on my barometer and the NWS (a government agency), I wouldn't be screwed".

Or.......
Safe in the knowledge that you have a private hot line to the NWS, you sneer at the bozo's who use an "unreliable" ADG. Gets close to race time, you got your barometer and temp/humidity gauge and your ready to jet. Intent on entering your numbers into your HP calc (complete with Reverse Polish Notation), you fail to see that guy lose control of his pit bike and bump into you.....Picking yourself up off the pavement, you reach for your calculator.....uh, oh, it's in more than a few pieces and the drop knocked the battery out killing the mem recall funcs (and anyways the Func key is broken) and you can't quite remember what that equation was for calc'ing Air Density (since you had it set up as a function and hadn't actually entered it manually in 2 years) And, of course, you can forget about the lookup tables for Corrected Air Density. And you think to yourself "Damn, if only I had used one of them (unreliable) ADG from Longacre as well (which is probably no more fragile than my once-working HP Calc), I wouldn't screwed."

(As long as we're painting silly scenarios, the other side should get equal time).

Me? I rely on the Longacre ADG - and keep a log with readings from it and a Davis Weather Station.

Charlie Mc
tz250 #90 Ex

[This message has been edited by CharlieM#90 (edited 08-04-2001).]

[Wera#124]

Originally posted by CharlieM#90:
Me? I rely on the Longacre ADG - and keep a log with readings from it and a Davis Weather Station.

Uh-huh...and a little O2 sesnor http://www.wera.com/ubb/wink.gif

(ps..drop me a line about next weekend..)

[mtk]

Charlie,

When you can answer "95% of what?" I'll consider your point valid.

[CharlieM#90]

As I will yours when you can guarantee a calculator that doesn't break or ever need new batteries.

Reliance on any single method for jetting is a fools game whether you calculate Air density/saturation with a barometer and calc, air density gauge, plug chop, or 02 sensors.