I cant seem to figure out why my '01 750 Dark keeps dying when i hit 120mph. It spudders a little then when I pull in the clutch the engine completely cuts off. I have to pull off the road then crank it over with the choke on for 2-3 min. I have been thinking I'm getting a lean condition or something because I have Remus slip ons and K&N filter with stock jets. any suggestions?
Sounds like the fuel pump isn't keeping up.
You might be a little lean with that set up, but the bike was lean stock and that wouldn't cause cutting out and dying.
Check all your lines for kinks and if you don't find anything it might be time for an electric pump.
edit....
when was the last time you replaced your filter?
Fuel filter? very recently, I'd say a month ago.
The '01 model has a fuel pump? I thought it was gravity fed with a regulator..? please, school me up on this.
Quote from: Skyshadow on June 14, 2011, 06:23:21 PM
Fuel filter? very recently, I'd say a month ago.
The '01 model has a fuel pump? I thought it was gravity fed with a regulator..? please, school me up on this.
They come from the factory with a vacuum operated fuel pump and fuel shutoff.
The pump is mounted to the frame on the r/h side. It is hexagonal. The fuel shutoff is mounted under the tank hinge.
It could be as simple as a bad vacuum line.
The monster will gravity feed to a point, but as the tank level drops it will stop feeding.
OOh, the doofis mech at the Duc shop in OKC said that was a fuel regulator. Is there a way i can check it before I go and replace it all together?
Quote from: Skyshadow on June 14, 2011, 07:08:36 PM
OOh, the doofis mech at the Duc shop in OKC said that was a fuel regulator. Is there a way i can check it before I go and replace it all together?
If you disconnect the line from the pump to the carbs and crank the engine fuel should spurt from the line. It won't be very much pressure or volume. It doesn't take much to supply a carbed engine.
I think your bike is telling you something. ;)
My bike did the same when I had the airbox lid off. I had the K&N with DP Conti pipes and stock jets and it would cut out around 110-115mph. I put the lid back on and it solved that problem. I'll be honest though, when I get the bike up to that speed, it feels like its going to lift off the road or rev out too high. I may be wrong but I'm not sure this bike is suited for sustained speeds like that. Aerodynamics definitely plays a part because my CBR600 could comfortably do 140mph without the wind drag or drifting.
Shit, my M750 struggles to with anything over 100. It may be diet time again. What kinda speed is the 750 capable of?
Quote from: Timmy Tucker on June 14, 2011, 08:21:08 PM
Shit, my M750 struggles to with anything over 100. It may be diet time again. What kinda speed is the 750 capable of?
You're not the only one. I can push it to a little over 100mph while fully leaned forward with a tail wind. Even then it feels like the bike is going to break apart. I've heard others with M750's say the same thing.
MAN...I got nothing to add except to say that when I read the thread title, I thought someone else was trying to push their Capirex to 140 and was trying to figure out why they failed.
Quote from: speedknot on June 14, 2011, 07:51:48 PM
I think your bike is telling you something. ;)
My bike did the same when I had the airbox lid off. I had the K&N with DP Conti pipes and stock jets and it would cut out around 110-115mph. I put the lid back on and it solved that problem. I'll be honest though, when I get the bike up to that speed, it feels like its going to lift off the road or rev out too high. I may be wrong but I'm not sure this bike is suited for sustained speeds like that. Aerodynamics definitely plays a part because my CBR600 could comfortably do 140mph without the wind drag or drifting.
Weird, mine sits around 7000rpm at that speed and seems pretty stable. I mean not like my old R6 and I doubt it could go much faster but without the cut off I think it would do just fine at those speeds.
Quote from: Timmy Tucker on June 14, 2011, 08:21:08 PM
Shit, my M750 struggles to with anything over 100. It may be diet time again. What kinda speed is the 750 capable of?
Weird again, I can keep my above 100 with ease. But I only weigh 160lbs... (not saying your fat though man lol)
I forgot to mention... I believe its universally accepted that the speedo is somwhere around 5-10mph off, on the high side. I did the GPS and Honda Civic digital dash ride along to confirm that my speedo shows 10mph faster.
Hey sky, did you check that your intake isn't taking in too much air? I mentioned how my Duc reacted in an earlier post and I distinctly remember that when I put the pods on my CB400F, the engine would skip and sputter when at high speeds or I got hit with a cross wind. That went away when I put the stock airbox assy. back on.
My 620 dies at 180! What can I do?
Quote from: Skyshadow on June 15, 2011, 09:53:39 AM
Weird again, I can keep my above 100 with ease. But I only weigh 160lbs... (not saying your fat though man lol)
Yeah, I've got 55-60 lbs on you. I suspect if I get back down to +/- 180 again, the bike will be much happier.
(I'm updating this thread instead or starting a new one cause I had good advice coming from you guys)
So Anyways, i learned that my bike will die like it does at 120mph if i go hard on the throttle for longer then about 15 sec. I have been able to temp fix the problem by opening my tank cap and when i do it makes a loud suction noise. Does this still sound like the fuel pump??
If you're getting a pressure change when you open the tank my guess is that you're looking at a problem with the venting. There should be a vent line keeping pressure inside the tank equal to outside air pressure.
Quote from: Skyshadow on December 04, 2011, 10:34:43 PM
(I'm updating this thread instead or starting a new one cause I had good advice coming from you guys)
So Anyways, i learned that my bike will die like it does at 120mph if i go hard on the throttle for longer then about 15 sec. I have been able to temp fix the problem by opening my tank cap and when i do it makes a loud suction noise. Does this still sound like the fuel pump??
That is definitely a vent problem.
If you no longer have the charcoal canister on your bike, remove the little rubber 'button' from under the gas cap.
Unless the problem is the cap itself that should solve the issue.
Oh i don't have a canister! man, you guys are effing brilliant... I hope that fixes it! I have a dent from tank slap... you think that would make the beast with two backs with my venting?
Quote from: Skyshadow on December 07, 2011, 06:20:51 PM
Oh i don't have a canister! man, you guys are effing brilliant... I hope that fixes it! I have a dent from tank slap... you think that would make the beast with two backs with my venting?
Dent shouldn't affect anything but appearance.
cool, you think that driving it before with the pressure fighting my pump could of messed up my pump?
Quote from: Skyshadow on December 07, 2011, 06:49:27 PM
cool, you think that driving it before with the pressure fighting my pump could of messed up my pump?
No clue
My M750 will do 108mph at 120 mph on the speedo timed using a Garmin satnav .
Quote from: jerryz on December 08, 2011, 08:28:06 AM
My M750 will do 108mph at 120 mph on the speedo timed using a Garmin satnav .
Good to know and why I'm going to swap out for a R6 gauge cluster and speedo.
So pulling that little black nipple worked for about 3 days but when my tank started getting low it went back to it's old ways. Thinking of going to a electric fuel pump, any ideas?
Quote from: jerryz on December 08, 2011, 08:28:06 AM
My M750 will do 108mph at 120 mph on the speedo timed using a Garmin satnav .
Exactly what mine does - Is your odometer off by about 10% also?
Skyshadow, have you changed the fuel filter?
Quote from: WarrenJ on January 02, 2012, 03:26:18 PM
Exactly what mine does - Is your odometer off by about 10% also?
Seems to be standard error, mine too.
Yea, twice since I bought it in '09. the current filter has been on it since last summer
Quote from: Skyshadow on January 02, 2012, 02:23:28 PM
So pulling that little black nipple worked for about 3 days but when my tank started getting low it went back to it's old ways. Thinking of going to a electric fuel pump, any ideas?
Stop driving 120. [thumbsup]
or maybe it's your M750 telling you that it doesn't want to go that fast on public roads. It wants to live long enough to see grand kids someday.
Quote from: Skyshadow on January 02, 2012, 02:23:28 PM
So pulling that little black nipple worked for about 3 days but when my tank started getting low it went back to it's old ways. Thinking of going to a electric fuel pump, any ideas?
It sounds like your vacuum pump is weak/not working.
I think an electric might just solve the problem
Quote from: ducpainter on January 06, 2012, 04:27:47 PM
It sounds like your vacuum pump is weak/not working.
I think an electric might just solve the problem
That's what I was figuring. What type of pump should i be looking into? I figuring I don't need one that pulls more then just a few PSI.
Quote from: Skyshadow on January 07, 2012, 11:00:02 AM
That's what I was figuring. What type of pump should i be looking into? I figuring I don't need one that pulls more then just a few PSI.
Something like this...http://www.davesdiscountautoparts.com/item.wws?mfr=BECK/ARNLEY&sku=152-0568&source=GOOGLEBASE (http://www.davesdiscountautoparts.com/item.wws?mfr=BECK/ARNLEY&sku=152-0568&source=GOOGLEBASE)
or this...http://www.lbcarco.com/electric-low-pressure-fuel-pump-fuel-filter-and-elements.htm (http://www.lbcarco.com/electric-low-pressure-fuel-pump-fuel-filter-and-elements.htm)
or you could go to auto-zone and see what they have.
Some people think a low pressure electric pump will cause float needles to leak.
I think 4 gallons of fuel under atmospheric pressure is stronger than 2.5-4.5 psi.
Either way, As long as the petcock shuts off the fuel, I dont have to worry about leaks.
Quote from: Skyshadow on January 08, 2012, 12:03:43 PM
Either way, As long as the petcock shuts off the fuel, I dont have to worry about leaks.
Petcock is only for when the bike isn't running.
Soo, I will have to run a fuel regulator?
Quote from: Skyshadow on January 08, 2012, 03:03:06 PM
Soo, I will have to run a fuel regulator?
I don't believe so.
If your float needles are in good condition the 3 ish psi the pump produces is less than than atmospheric pressure.
At least that's my thinking.
Gasoline will produce .295 psi per foot of depth. Quantity of gallons does not matter, just the depth.
Since you don't have a full foot of fuel depth a 3 psi pump will be putting more than 10 times the pressure against the float valves as a gravity system. Since it already has a fuel pump the floats are designed to stop a certain amount of pressure. Adding more pressure will overdrive the floats and cause fuel to flow when it shouldn't as DP has said.
The 3 psi rating of the fuel pump includes atmospheric pressure but it makes no difference because atmospheric pressure is exerted against the fuel in the bowls also (14.7 -14.7 = 0). There are gauges that read in absolute pressure pressure but they are for specialized applications and do not apply here.
Not saying it won't work fine but rather just reporting the physics correctly.
C-14
^ I'm not fully sure what your saying here but I believe it means I need a regulator... (Good info though man!)
Quote from: Skyshadow on January 08, 2012, 08:37:19 PM
^ I'm not fully sure what your saying here but I believe it means I need a regulator... (Good info though man!)
It depends on the output of the original system. The floats were designed for a specific pressure. A little less should be okay as they open the needles by losing flotation when the fuel level in the bowl is low. Too much pressure will force fuel past the needles all of the time.
3 psi is quite low. I actually think it should be okay. The part that's missing here is knowing what the output pressure of the vacuum pump should be.
You may be reducing the output of the vacuum pump with the open air box. If you need to go 120 you may want to consider returning the airbox to OEM spec.
And to those who say you don't need to go 120 [thumbsdown]
ok, cool. I'm not a fan of the vacuum set up and need to lose it for my next mod anyways so I think I'll go electric with a regulator to be safe.
Quote from: Skyshadow on January 09, 2012, 01:14:37 PM
ok, cool. I'm not a fan of the vacuum set up and need to lose it for my next mod anyways so I think I'll go electric with a regulator to be safe.
What pressure are you going to regulate it to?
You don't know for certain that 3 psi is too much...do you? ;D
No, but from Duccutters i know what pressure i need to do what I'm doing.
If your 750 can do 120mph then its running great.
Quote from: Skyshadow on January 09, 2012, 06:59:48 PM
No, but from Duccutters i know what pressure i need to do what I'm doing.
So...
what pressure is that?
3 psi over atmosphere at normal op and 10 psi at full boost.
full boost?
Full boost?! So you have evil plans [evil]?
I just wanna see this magical pressure regulator that recognizes full boost. ;D
Quote from: ducpainter on January 10, 2012, 06:39:21 PM
I just wanna see this magical pressure regulator that recognizes full boost. ;D
http://www.duccutters.com/pdf/FuelSystem.pdf (http://www.duccutters.com/pdf/FuelSystem.pdf)
Not magic, they have been around for DECADES! You know I am always so amazed by how comfortable people get with electronic controlled boost applications and lose all faith in old school vacuum controlled turbo applications. I just had a friend that built and owned a boosted GTI and asked me seriously if it was possible to boost his '71 BMW 2002. He didnt know how he could control the fuel without a ECU doing all the work.
What are your plans for the fact that the fuel tank outlet is only 5/16"? Plan on building something?
...and how did we go from a missing fuel pump to turbo charging? [laugh]
Quote from: ducpainter on January 11, 2012, 04:10:18 AM
What are your plans for the fact that the fuel tank outlet is only 5/16"? Plan on building something?
...and how did we go from a missing fuel pump to turbo charging? [laugh]
Umm, we may have got carried away. lol My plan for the tank is...
http://www.motorcyclistonline.com/gearbox/new_products/122_1005_california_cycleworks_track_tank_for_ducati_monster/index.html (http://www.motorcyclistonline.com/gearbox/new_products/122_1005_california_cycleworks_track_tank_for_ducati_monster/index.html)
I believe that tank also uses a 5/16" outlet.
Quote from: ducpainter on January 11, 2012, 01:37:47 PM
I believe that tank also uses a 5/16" outlet.
Then we'll just have to see how much fuel we can squeeze thru that little hole.
Quote from: Skyshadow on January 11, 2012, 04:22:20 PM
Then we'll just have to see how much fuel we can squeeze thru that little hole.
Last I heard, I thought Chris was re-doing the mold.
Are the tanks readily available?
yea, your right. he is so they are not available right now. I'm going to try to talk him into putting a larger outlet nozzle on it ;D