Poor Fuel Milage 2007 Nomad

[macmac]

The OP's bike has no goat bladder and is de-baffeld... That won't work.....

[jay02904]

not sure if you noticed but i just published my dyno results from the other day with an 08 nomad 9100 miles 93 octane 10w40 syn. v&h, fi2000, air kit, and reed vavles. i get about 30mpg's...lots of hwy and lots of throttle i bet i could get 35 mpgs if i drove "normal". but i ended up getting 65 hp and 85lb/ft torque @ 5800 rpm in 4th gear. It sounds like something may be off on your settings. some of the guys have made some good suggestions and are pros compared to me but thought this info may be helpful! good luck

[ba47]

Originally Posted by macmac

Did you buy the bike this way or did you make it this way?

My bike is set up with a right side only air filter exposed to rain, a TFI, V&H Baggers, coasters, No ISc's, and screems for a Nomad. It will burn rubber leaving a light and it wears a Dunlop SP 5000 car tire too boot.

.

this is the way the bike came, previous owner said he was getting in the 40s so I am just trying to figure out what changed.. Baggers are in the future, but need to build the savings account back up a little.

Thought about taking the Dynojet off, I have the software to program so I'll play around with the settings a little, can't get much worse than it is.

Thank you everybody for all the suggestions, I really like the spirit of this board

Dick Strickland
Grand Island NE

[cactusjack]

Originally Posted by ba47

this is the way the bike came, previous owner said he was getting in the 40s so I am just trying to figure out what changed.. Baggers are in the future, but need to build the savings account back up a little.

Thought about taking the Dynojet off, I have the software to program so I'll play around with the settings a little, can't get much worse than it is.

Thank you everybody for all the suggestions, I really like the spirit of this board

Dick Strickland
Grand Island NE

Before you go changing things, export the current map to your laptop so you can import it again if needed. Then go to Dynojet's website and download map #220-001 (completely stock bike), see if that gives you any change, good or bad.

Also, clean the throttle body as someone suggested earlier.

Let us know the result.

[ba47]

Originally Posted by cactusjack

[quote author=ba47 board=nomad thread=19773 post=297864 time=1284409030]



Before you go changing things, export the current map to your laptop so you can import it again if needed. Then go to Dynojet's website and download map #220-001 (completely stock bike), see if that gives you any change, good or bad.

Also, clean the throttle body as someone suggested earlier.

Let us know the result.

Pretty much what I was planning to, I let you know how I come out.

Your bike could be a twin to mine, except I have a 5" tall clear windshield, but planning going to the low black one like yours, and my tour pack came of a Harley Ultra.

Thanks again everyone for all the help[
Dick

[cactusjack]

Originally Posted by ba47

Pretty much what I was planning to, I let you know how I come out.

Your bike could be a twin to mine, except I have a 5" tall clear windshield, but planning going to the low black one like yours, and my tour pack came of a Harley Ultra.

Thanks again everyone for all the help[
Dick

The shield shown in those pictures is a 6" dark tint. I have been using an 8" medium tint for the summer. I just now ordered a 10" medium tint that I want to try for awhile.

[macmac]

You might work up some form of temp baffels too, just to try.

What is taking the place of that goat belly anyway?

If this is truely a no back pressue bike i can hardly belive it isn't falling flat on it's face. But the dyno figures say it is.......

[redjay]

I posted recently that my performance dropped off after I gutted the goatbelly. I only had it on one day so I did not get chance to check the fuel mileage. Hated the sound of it.
With the debaffled stock mufflers, a Dobeck TFI and 9" air filter on the right side (Caddman Mod) my bike has lots of ooomph and will go 240 kms before I get to the last bar on the fuel gauge. 05 Nomad.

[AlabamaNomadRider]

I would see about getting another goat bladder or go with after market pipes.

[macmac]

Red, Well yeah if grab a fist full of throttle and romp up the wick hard, open straight pipe set ups work. The problem is staying at 5,200 RPM all the time.

That won't be economical or even legal in most places other than a track.

The loss of back pressue is where the RPM for torque is made most, and where most Nomad riders ride. Lower rpms lots of romp.

There is a force in back pressure, that the pistons create pushing waste gasses out the pipes, which assists in the over lap the intake valves have, which are begining to open before the exhaust valves are closed, in such a way that the new fuel air charge is busted up (atomized) more, which makes the burn cleaner and have as much power as possible.

A Nomad has such big pistons, it can compensate for a loss of back pressure, but in rpm bands if you get it real wrong the Nomad will still fall flat.

Other bikes and even cars are much more sensitive. The Nomad seems to not have a best power band. It is a grunt engine compared to R bikes.

Other smaller bikes like my ancient 850 triple have a RPM band where the thing busts into life.

Somew where around 5,500 rpm that little 850 just takes off, and RPMs jump radically fast, which IS the Band, and will run right up to with in 15% of red line nearly instantly.

If I opened up the exhaust on that bike it would not respond for beans.

Smaller cars suffer power loss to when the pipes or mufflers have big leaks.

If you look at dragsters they have nothing but head pipes, andit works because the gas pedal is mashed to the floor boards, only.

If you look at most other race cars made for tracks like bike tracks are set up, they will have exhaust systems tuned to make power in some RPM band.

Indy cars going on a oval track are dawgs untill they build some rpm. They can hardly get out of the pits sometimes, before they are in their rpm band, because the exhaust is too open.

Many engines are effected by back pressure, which is the devils work to explain for me.

The best way to see it work is to seek out 2 stroke chain saws with race mufflers on them. Some of the prinicplas are different, but it still works in a some what similar way.

[blowndodge]

Mac that was impressive!!

To further your explanation during overlap as mac pointed out with both intake and exhaust valves are open ever so slightly some of that fresh fuel charge flies out the exhaust port into the exhaust whereby the back pressure and moving piston suck this unspent fuel mixture back into the engine almost like a very mild "blower" effect.

Different diameter and length of exhaust, port diameter, piston size, cam profiles and other factors determine at what rpm best utilizes this back flow phenomenon

[dogdoc]

+1 TC except he rides 45 mph so good mileage. :-)

[Top Cat]

Originally Posted by Doc (Lonewolf)

+1 TC except he rides 45 mph so good mileage. :-)

What? You saying I ride 45 mph? I never go that fast, to afraid

[macmac]

Thxs BD..... That is correct. Sorry about my typos.. To see this in a working onm loine moving diagram the back pressue is like a spring, drawing in more fuel and then slaming it back into the combustion chamber.

I don't have the right abilty to articulate this action, but there IS valve over lap, which causes this to happen and with no back pressure it won't happen a bit.

I don't have a decent working moving diagram and don't even know what to call it on line.

[rhunt4]

I only average around 32 on my 2007 and I have done every thing on the board to mine cobra tfi cadman mods de bladderard the goat belly. It does run good though