my 900f on the dyno!

Posted: Sat Sep 29, 2007 8:52 pm

AlaskaGriz wrote:

Period correct is not my first requirement.

Obviously - if it was, you wouldn't have that goofy looking Cobra exhaust Razz

.

Posted: Sat Sep 29, 2007 9:57 pm

burned wrote:

razor02097 wrote:

Hmmmm... I though vacuum raises the vacuum slides...

no vacuum at WOT? OH NOES!!! I better hook up the hoover to my brake booster if I drag race my car today Shocked

just hook up a vacuum gauge and watch it.

you have a funny way of drag racing,wot and on the brakes.

burnout dude... I was talking about the burnout Rolling Eyes

Posted: Sat Sep 29, 2007 10:35 pm

you step on the brake before you go wot for the burnout dude. Rolling Eyes

regardless you know a brake booster has nothing to do with what we are talking about here.

they are CV carbs.constant velocity.the slides do not work on vacuum.you can operate them with a air blower.

Posted: Sat Sep 29, 2007 10:50 pm

burned wrote:

yah,its good gig.

ive been running a dynojet dyno for 17 years.

i build high end supermoto race motors for a living.

i generally be found at thumpertalk.com

i have my own jetting forum and im the senior member there.40,000 posts.

Welcome burned. Please ignore some (many) of the rocks that will soon be coming your way, as I suspect you might shake up some of the convential wisdom that is derived from seat of the pants tuning around here.

Posted: Sat Sep 29, 2007 10:58 pm

thanks!

partially my fault for not introducing my self.

i want to say up front that i am not here to cuase trouble.

i deal with that at thumpertalk all to much.

ive been reading here for quite some time.lots of good info here but there i also a ton of lot misinformation that seems to just get parotted over and over.

i think if the few that seem to doubt me would just check out my back ground a little they would realize im not just some guy that thinks i know what im talking about.

thanks for having this site for all to enjoy! Smile

Posted: Sat Sep 29, 2007 11:01 pm

burned wrote:

you step on the brake before you go wot for the burnout dude. Rolling Eyes

regardless you know a brake booster has nothing to do with what we are talking about here.

they are CV carbs.constant velocity.the slides do not work on vacuum.you can operate them with a air blower.

I have a stick I can't step on the brake first nor do I have a line lock, I win Razz

Posted: Sat Sep 29, 2007 11:08 pm

fasterspider wrote:

Lose the shitty pods and put the air box back on and gain about 8 HP to put it where it was before you broke it with the jet kit & pods.

Dude, don't mind Ray. He comes off a little rough, but he means well. PODS is a very sore subject around here. It's been beaten to death many times over. Most of the people here had bad runnings with pods, so the stock airbox is the general consensus. My first F was a 900, and very shortly after getting it I bought a V&H Supersport pipe and stage 3 Dynojet kit with K&N pods. It ran like crap after the the jet kit, no matter what I did. I had no idea how to tune CV then, 17-years old with mostly S&S Harley carb experience. I had it dyno tuned in NH, and the guy had it running like a top with all Dynojet stuff. It lost some power in the bottom end, but above 5grand it pulled like mad. It spun the back tire every hard shift all the way to 4th gear. It worked great for me for good 35,000 miles later. So I was a firm believer. Just recently, I got a CB750F with CVs and same dynojet kit, and it ran like total crap. I copied my 900 set-up, no luck, tried everything according to the manual, Sonic, and everything I could think of. It ran better in the end, but far from good. Seems like some people fair better than others.
I've got two guesses. The metal to metal vaccum slide seal we got in the junky factory carbs can ware and get blow-by loosing correct proggressive lifting action. And valve timing and clerance. My 900 had it's valves checked every season and I tightened the cam chains religiously. The 750 has questionable service history, and I have yet to check the valves. Our chain tensioners suck and chain stretch can cause timing retard. The valve clerance can cause vaccum issues. Long story short, maybe it's not the pods, it's just how pods work with other tear and ware issues.

Posted: Sun Sep 30, 2007 12:18 am

burned,

Welcome to the forum. I believe you said that you were using stock needles in your CV's, did you have to shim them or were they rich enough as-is?

Posted: Sun Sep 30, 2007 1:52 am

A couple of really important things come to mind here. What is a 124 main jet? Honda and round head Mikuni like for a Z-1 are measured by the hole size in metric units. This is 120,122.5,125,127.5,130,etc. Numbered American drills are not consistant steps and also not metric sizes,but may be close at certain sizes.

Posted: Sun Sep 30, 2007 4:41 am

CB1100Fun wrote:

burned,

Welcome to the forum. I believe you said that you were using stock needles in your CV's, did you have to shim them or were they rich enough as-is?

stock needle no shim.i only only richened the primary main jet to a 82.5.

the high rpm steady throttle is perfect.the shim would only effect this range.

Posted: Sun Sep 30, 2007 4:43 am

sonicrete wrote:

A couple of really important things come to mind here. What is a 124 main jet? Honda and round head Mikuni like for a Z-1 are measured by the hole size in metric units. This is 120,122.5,125,127.5,130,etc. Numbered American drills are not consistant steps and also not metric sizes,but may be close at certain sizes.

im using dynojet main jets.i have tons of them so its easy.

as to what a 124 dj main is compared to a kehin or mikuni main not 100% sure as like you point out its tough to measure accurately.

Posted: Sun Sep 30, 2007 4:49 am

7Eleven wrote:

fasterspider wrote:

Lose the shitty pods and put the air box back on and gain about 8 HP to put it where it was before you broke it with the jet kit & pods.

Dude, don't mind Ray. He comes off a little rough, but he means well. PODS is a very sore subject around here. It's been beaten to death many times over. Most of the people here had bad runnings with pods, so the stock airbox is the general consensus. My first F was a 900, and very shortly after getting it I bought a V&H Supersport pipe and stage 3 Dynojet kit with K&N pods. It ran like crap after the the jet kit, no matter what I did. I had no idea how to tune CV then, 17-years old with mostly S&S Harley carb experience. I had it dyno tuned in NH, and the guy had it running like a top with all Dynojet stuff. It lost some power in the bottom end, but above 5grand it pulled like mad. It spun the back tire every hard shift all the way to 4th gear. It worked great for me for good 35,000 miles later. So I was a firm believer. Just recently, I got a CB750F with CVs and same dynojet kit, and it ran like total crap. I copied my 900 set-up, no luck, tried everything according to the manual, Sonic, and everything I could think of. It ran better in the end, but far from good. Seems like some people fair better than others.
I've got two guesses. The metal to metal vaccum slide seal we got in the junky factory carbs can ware and get blow-by loosing correct proggressive lifting action. And valve timing and clerance. My 900 had it's valves checked every season and I tightened the cam chains religiously. The 750 has questionable service history, and I have yet to check the valves. Our chain tensioners suck and chain stretch can cause timing retard. The valve clerance can cause vaccum issues. Long story short, maybe it's not the pods, it's just how pods work with other tear and ware issues.

im not offended and i definately dont get chased off easily.

i agree that there are lots of factors in dealing with 25 year old motorcycles.

the motor in my F is pretty tired.it puffs pretty good on hard decel.still runs prefectly.

trying to jet anything by driving around trying to "feel" the difference is a huge pain.weve all done it.

a dyno with a proper wideband a/f meter is like cheating.

Posted: Sun Sep 30, 2007 4:54 am

yeah, plug reading with heat hardened valve stem seals is pretty moot Wink

Posted: Sun Sep 30, 2007 5:02 am

plug reading regardless with modern fuels doesnt work.to many additives.the plugs look lean when they really are not.

trying to jet by looking at the plugs has people chasing there tails more often than not.

when i got my first wideband i was like "no wonder!".you would be suprised how far off the jetting can be and still "feel ok" or "plug looks good".

Posted: Sun Sep 30, 2007 5:06 am

Makes perfect sense to me, thanks. I had previously noticed I liked a leaner than expected plug color.

Have you tried the Colortune plugs that have a window to the combustion chamber?

I am seriously considering a sophisticated removeable on-board wide band AF system and have previously posted about it. Wink

Posted: Sun Sep 30, 2007 5:09 am

never tried the color tune deal,but also seem very subjective to fuel.

widebands are very affordable these days.easily had for $350 ish.

i paid $1500 for my first one. Shocked

Posted: Sun Sep 30, 2007 5:21 am

My plan is for a good datalogging wideband fed to a Veypor aux in and 35mm FCRs modded with a TPS. Dyno on a bike, real world data.

Posted: Sun Sep 30, 2007 5:25 am

Well a lot of the time the dyno jet "jets" are specials made so the bike will run. They realized that advertising sells jet kits,so most people "think" big jets means go fast,so they put small jets with big numbers on them.

A CV carb needs to be lean to work pure and simple. A lean engine makes power a rich running one does not.

If a CV carb is truly lean after a certain amount of throttle twist,say 1/2 throttle,the remaining amount of throttle will have no effect on vehicle performance. The reason the slides lift to the amount of fuel supply and no further even though the butterfly is fully open. If it is rich the slides only lift so far,or may go to the top then drop due to the lower vacuum of a rich running engine.

On a regular carb the fuel is supplied strictly by Bernoulli,air cleaner or not. The air speeds up through the venturi and the lower pressure supplys the fuel. The normal CV carb is restricted by the air filter/airbox similar to the restriction the "choke" does to increase the amount of fuel for starting. The smallish main jet size seen stock has nothing to do with the correct amount of fuel.

Now after you remove the airbox all the calculations change but eventually you find the correct jetting again.

What I see happen is driving versus dyno man. The airbox makes a restriction that makes the slides lift. Without the restriction of the airbox using pod filters or none,on throttle hit the slides drop,the fuel is cut off and bog happens until the slides finally open again and with it the fuel. Similar happens attempting to use any CV on a dragbike with a 2-step. On real carbs the throttle is held wide open on the start line the ignition control holds RPM at your selected launch,so it is "loaded up" with fuel and full airflow,to take the "hit" on the clutch engage. Try this on a CV carb and the slides will be near bottom to drive off like this until they finally open up.

Drilling the lift holes helps increase the opening speed of the slide,from "Florida blue hair" slow to decent. Regardless there is a "D E L A Y" in the slides lift on purpose so the typical dipshit will not flip the bike over. The latest bikes have either "fly by wire" to slow opening,or sometimes even a vacuum piston,or even a servo motor controlled by the computer and seen on a dyno these do not open until some 9000 RPM on bikes like the ZX-14.

In real terms the 900 uses a 32mm throat CV carb that by my measure is 37mm at the spigot. On my race bikes I used a 37/38mm regular slide carb that would hit so hard on throttle hit to strike a 8 1/2" slick 7" on the ground and paint a black line like it was spray paint,"bog" was not a concern,traction was.

Never ran on the mountain,power goes down a lot from altitude,so conversion for corrected altitude should relate what you get to what I see. At the Brute Horsepower Shootout at Daytona in 1992 I saw all kind of bikes. My Honda made 145 HP. A nice looking CBX made 78 HP. The typical Triumph/Norton/Harley made around 50 HP. All of these are at the typical sea level of Daytona,and no I do not recall the actual corrected altitude then. I do know that one of my fellow racers with a Z-1 based bike made 108 HP and commented,no wonder you can play with us on top end. I led that deal all week until Dennis Dismet rode in on a unassuming looking GSXR,the turbo hidden by bodywork and won the deal making 342 HP. Now normally aspirated are in a different class than boosted bikes,but the record is over 700 HP using an intercooled tubocharged Hayabusa. The limiter is the splines in the clutch hub shearing off. These bikes are routinely "detuned" to 500 HP or so and run in streetbike trim,no wheelie bar or slick,at the 6.90@200+ MPH range.

Posted: Sun Sep 30, 2007 5:25 am

I'm not plumbing boost on these motors... Wink

What do you think of the Flow Commander systems for the FCRs?

Posted: Sun Sep 30, 2007 5:38 am

dynojet mains are very close to mikuni mains or at least as near as you can tell with number drills.

a 125 mikuni main is between a 124 and 126 dj main.

dynojet is in the business of selling jets with out a doubt.

i agree that the slides ability to reach full open is dictated by the jetting.if the motor cannot go full rpm the slide will not raise.

the velocity of the air raising the slide is dictated by rpm.

i tune a 500hp turbo busa...........

Posted: Sun Sep 30, 2007 5:39 am

genesound wrote:

I'm not plumbing boost on these motors... Wink

What do you think of the Flow Commander systems for the FCRs?

the flow commander does not work as advertised.

altering the main air correction is not the same and changin the main jet.

Posted: Sun Sep 30, 2007 5:40 am

OK, but how does that translate into altitude and weather compensation?

Posted: Sun Sep 30, 2007 5:45 am

the fcr is really not that sensitive to minor changes in conditions.

the flow commander only gives external adjustment to the air correction circuits.

closing off or opening the air to the main circuit isnt the same as adding or subtracting fuel via the main jet.they have different effects.

Posted: Sun Sep 30, 2007 5:57 am

I get that, but what about at 4000' or more of altitude on a bike setup on the beach?

I'm not racing either, well not officially, I just want something that will cross the Continental Divide comfortably with better performance than CVs with an airbox with a bike that kicks ass in L.A.. Laughing

I already have the FCRs and the Flo Commanders, i'm just loking for some enlightenment and a clue Wink

You are at pretty high altitude already, that may explain away some of your findings with pods vs. airbox BTW Wink

Posted: Sun Sep 30, 2007 1:48 pm

my suggestion is to sell the flow commanders.no matter how much you turn the screws it wont help with the altitude.

if you get your FCR set up perfectly at sea level,it will go up over 4000 acceptably.it will rich but should run ok.

however if they are set rich at sea level it will be a slobbering pig in the mountians.

the main jet is most effected circuit,followed by the needle then the pilot circuit.

as to my altitude,if you go by the thoery around here i would be having a harder time with pods as there is less vacuum the higher alt you go.

it just getting the correct jetting.

Posted: Sun Sep 30, 2007 2:18 pm

Is your shop the old Excel Motorsports on E Colfax?

Posted: Sun Sep 30, 2007 2:27 pm

jayhawk wrote:

Is your shop the old Excel Motorsports on E Colfax?

yes,we were bought out in march.we are now OTD cyclesports.

do i know you?

Posted: Sun Sep 30, 2007 2:34 pm

Probably not I don't get out much!!!
I a a one owner 1980 750F with a baracuda exhaust and CRS carbs.

Posted: Sun Sep 30, 2007 2:37 pm

jayhawk wrote:

Probably not I don't get out much!!!
I a a one owner 1980 750F with a baracuda exhaust and CRS carbs.

call me or just come by some time with it.i would love to run it on the dyno.

303 399 5370 is the direct line to the shop.

my name is Eddie

i have ton of left over 750 and 900 parts if you need anything.

im building a 900 super f and bought a 750 parts bike that i really only needed the stator cover and stator from (mine was missing completely).

Posted: Sun Sep 30, 2007 3:03 pm

Rick here. That would be great. I've always wondered how close Sudco jetted the CRS carbs when they sold them to me.

I'll call.