Javier, I would still do a quick check on the petcock. Pull the vacume line off the #2 carb and connect it to the mightyvac you just purchased and apply vacume, if it wont hold vacume then it probably has a hole in the diaphragm. You wouldn't see any fuel unless the carb fuel bowls have a bad gasket or fill up to the point to where they dump gas from the vent, but that doesn't mean that gas is not going past the diaphragm and down the vacume line into the #2 cylinder. You could also have a piece of crud holding open the float valve in a carb/ carbs, which would cause a rich running condition. In order for that to cause fuel to leak into the cylinder while sitting though, it would still rely on a bad petcock as if it was working properly there would be no gas going to the carbs when shut off. It definately sounds like you are getting too rich of a mixture on the idle circuit. The reason why you normally can't touch the throttle when cold is because bike carbs don't have a spray bar so they just dump raw fuel into the venturi. This doesn't atomize the fuel well unless the carb is warm, so the engine runs lean, when you open the throttle you just make it more lean and the engine will shut off. So if you need to open the throttle to get it to start then it is getting way too much gas. Once the engine is running especially at a higher RPM you need more than the idle circuit to supply the gas and these NH are lean running to begin with so a little extra gas probably just makes it run better. Also if subsequent starts are easy then it may be a slow gas leak, like Kurt said. I would also let it sit overnight and pull the plugs if any of them smell strongly of gas then that cylinder is probably the culprit, i would then start it up then shut off the engine and pull the spark plugs again, the plugs in the rich cylinder/s will be black and sooty possibly even wet with fuel. The last thing I can think of would be a stuck choke/enrichment valve.
On Aug 26, 11:44 am, Javier Garcia <[email protected]> wrote: > Last time I filled out the tank before this issue was Monday morning, at the > usual Shell station. It is a single hose, so the chance of getting a > different grade is non-zero. I cannot remember if the diesel is in the same > pump, but I'll expect a much bigger mess if I would filled up with diesel. > Could it be just that I used a low octane gasoline, instead of the usual > one? Yesterday after getting home I went to fill the tank again, just in > case it was a leaking gas problem. I am sure I did use premium yesterday > since I saved the receipt. > > Javier. > > > > On Thu, Aug 26, 2010 at 11:32 AM, Joey Kelley <[email protected]> wrote: > > Javier, > > Any chance you filled up at a pump that has a single hose and > > got either low grade fuel or Diesel or some other form of contaminant > > in the tank? > > -Joey > > > On Thu, Aug 26, 2010 at 11:23 AM, Javier Garcia <[email protected]> > > wrote: > > > Kurt, > > > > yes, I guess it does makes sense. In any case I think I need to gather > > more > > > information to make a consistent statistics of the behavior. All that I > > can > > > say so far is that it actually feels to be the other way around. When I > > > started having the issue yesterday, every subsequent start would be more > > > difficult than the previous one. After letting it seat the whole night, > > this > > > morning feels like the excess of gas is gone. Again, I am just bouncing > > > ideas between my gigantic ignorance about engines and the lack of > > > information about the symptom itself. > > > > Javier. > > > > On Thu, Aug 26, 2010 at 11:06 AM, Kurt Nolte <[email protected]> > > > wrote: > > > >> Javier, > > > >> It could still work with the "leaking petcock diaphragm" theory. When > > >> you let the bike sit for a while, a slow leak has a chance to put out > > >> enough gas to cause a starting problem. Once that gas is dealt with by > > >> your initial difficult start, subsequent starts without a long wait > > >> will be "problemless" because the leak hasn't had a chance to move > > >> enough gas. > > > >> If you don't have the problem again when you go home from work > > >> (several hours from now, unless I'm mistaken), then you indeed have a > > >> somewhat confusing issue. > > > >> It's possible that suddenly having to use the petcock more often could > > >> have caused a small tear in your diaphragm... thus the sudden onset of > > >> the problem without much warning. > > > >> That help at all? > > > >> -Kurt > > > >> On Thu, Aug 26, 2010 at 10:39 AM, Javier Garcia <[email protected]> > > >> wrote: > > >> > Hi guys, > > >> > thanks a lot for such educational answers. Now I am a bit more > > confused > > >> > than > > >> > yesterday. This morning I checked again for leaking. Nothing. Engine, > > >> > parts, > > >> > and garage floor all very clean. I went to start the same way I always > > >> > do, > > >> > no choke (at least not this time of the year), and no gas. It tried to > > >> > fire > > >> > up a couple of times, but not quite there yet. I had to give it a bit > > of > > >> > gas > > >> > and then went on. Just a bit rough at the beginning, but mostly from > > >> > being > > >> > cold. Putted my gear on and the bike is idleling perfect as usual. > > Took > > >> > it > > >> > outside and I turned off because I forgot something inside the house. > > >> > Came > > >> > back, hit the start, and fire up without giving any gas. Lucky I > > guess. > > >> > Came > > >> > to work, and I did not experience any of the symptoms from yesterday. > > >> > Pulled > > >> > over in the parking lot. Turned off. Hit start and it fired up > > >> > immediately > > >> > as usual. Tried 4 or 5 times consecutively. The same. The problem is > > >> > gone. > > > >> > Now, according to the general consensus, the diaphram in the petcook > > >> > could > > >> > be responsable for this issue. How does this scenario fits now? I > > >> > actually > > >> > was thinking what I have done differently recently, and one thing is > > >> > that > > >> > since my speedometer cable broke, I cannot calculate the gas level, > > and > > >> > thus > > >> > now I wait until I am empty and I have to change to reserve to go to > > the > > >> > station and fill up the tank. The difference now is that I am using > > the > > >> > petcook more often, swiching between tank and reserve. Before, I > > pretty > > >> > much > > >> > never touched it. > > > >> > Could it be also that going to reserve I just picked up some dirt > > >> > deposited > > >> > at the bottom of the tank, and then when to the carbs. I guess I could > > >> > try > > >> > Seafoam as well, just as a sanity check. > > >> > I will let you know how it behaves when I get off work. > > > >> > Thanks again for your opinions. > > >> > Javier. > > > >> > On Thu, Aug 26, 2010 at 8:55 AM, Kurt Nolte <[email protected] > > > >> > wrote: > > > >> >> After that, start wondering about float valve seats. Well, if it > > still > > >> >> gives you problems after you've made sure that the carburetors > > weren't > > >> >> at some point adjusted for a slight fuel leak into the intake, that > > >> >> is. > > > >> >> On Thu, Aug 26, 2010 at 8:39 AM, [email protected] > > >> >> <[email protected]> wrote: > > >> >> > I agree with replacing the petcock diaphram, i would even go as far > > >> >> > to > > >> >> > not check it, just replace it.... After that look at your vac > > lines, > > >> >> > then i > > >> >> > dont know after that.... > > > >> >> > Good luck > > > >> >> > -----Original Message----- > > >> >> > Date: Thursday, August 26, 2010 6:40:24 am > > >> >> > To: "Nighthawk Motorcycle Lovers!" > > >> >> > <[email protected]> > > >> >> > From: "jaybird248" <[email protected]> > > >> >> > Subject: [Nighthawk Lovers] Re: Fuel related problem > > > >> >> > Javier, the reason you have to give it lots of throttle to start is > > >> >> > that it's flooded. Opening the throttle lets in more air, diluting > > >> >> > the > > >> >> > accumulated gas to the proper mixture. Then the engine can fire up. > > > >> >> > I also had this symptom due to a torn petcock diaphragm. > > > >> >> > Jay S > > >> >> > 92 NH750 > > >> >> > South Florida > > > >> >> > On Aug 26, 5:39 am, jaybird248 <[email protected]> wrote: > > >> >> >> Absolutely check the petcock, as surfswab says. These symptoms are > > >> >> >> exactly like what happened on my bike and it turned out to be a > > >> >> >> small > > >> >> >> hole worn in the diaphragm. When I replaced the defective unit, > > not > > >> >> >> only did the symptoms clear up, my gas mileage went from the 40s > > >> >> >> into > > >> >> >> the 50s. > > > >> >> >> Jay S > > >> >> >> 92 NH750 > > >> >> >> South Florida > > > >> >> >> quoted text - > > > >> >> > -- > > >> >> > You received this message because you are subscribed to the Google > > >> >> > Groups "Nighthawk Motorcycle Lovers!" group. > > >> >> > To post to this group, send email to > > >> >> > [email protected]. > > >> >> > To unsubscribe from this group, send email to > > >> >> > [email protected]<nighthawk_lovers%[email protected]> > > . > > >> >> > For more options, visit this group at > > >> >> >http://groups.google.com/group/nighthawk_lovers?hl=en. > > > >> >> > -- > > >> >> > You received this message because you are subscribed to the Google > > >> >> > Groups "Nighthawk Motorcycle Lovers!" group. > > >> >> > To post to this group, send email to > > >> >> > [email protected]. > > >> >> > To unsubscribe from this group, send email to > > >> >> > [email protected]<nighthawk_lovers%[email protected]> > > . > > >> >> > For more options, visit this group at > > >> >> >http://groups.google.com/group/nighthawk_lovers?hl=en. > > > >> >> -- > > >> >> You received this message because you are subscribed to the Google > > >> >> Groups > > >> >> "Nighthawk Motorcycle Lovers!" group. > > >> >> To post to this group, send email to > > [email protected]. > > >> >> To unsubscribe from this group, send email to > > >> >> [email protected]<nighthawk_lovers%[email protected]> > > . > > >> >> For more options, visit this group at > > >> >>http://groups.google.com/group/nighthawk_lovers?hl=en. > > > >> > -- > > >> > You received this message because you are subscribed to the Google > > >> > Groups > > >> > "Nighthawk Motorcycle Lovers!" group. > > >> > To post to this group, send email to > > [email protected]. > > >> > To unsubscribe from this group, send email to > > >> > [email protected]<nighthawk_lovers%[email protected]> > > . > > >> > For more options, visit this group at > > >> >http://groups.google.com/group/nighthawk_lovers?hl=en. > > > >> -- > > >> You received this message because you are subscribed to the Google > > Groups > > >> "Nighthawk Motorcycle Lovers!" group. > > >> To post to this group, send email to [email protected]. > > >> To unsubscribe from this group, send email to > > >> [email protected]<nighthawk_lovers%[email protected]> > > . > > >> For more options, visit this group at > > >>http://groups.google.com/group/nighthawk_lovers?hl=en. > > > > -- > > > You received this message because you are subscribed to the Google Groups > > > "Nighthawk Motorcycle Lovers!" group. > > > To post to this group, send email to [email protected]. > > > To unsubscribe from this group, send email to > > > [email protected]<nighthawk_lovers%[email protected]> > > . > > > For more options, visit this group at > > >http://groups.google.com/group/nighthawk_lovers?hl=en. > > > -- > > -Joey Kelley > > Need Computer Technical support? > >http://www.crossloop.com/JoeyKelleyComputerServices > > At your service - via remote control! > > > -- > > You received this message because you are subscribed to the Google Groups > > "Nighthawk Motorcycle Lovers!" group. > > To post to this group, send email > > ... > > read more »- Hide quoted text - > > - Show quoted text - -- You received this message because you are subscribed to the Google Groups "Nighthawk Motorcycle Lovers!" group. 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