My bike's previous owner had the cap vent problem with fuel starvation. He said a mechanic drilled a very tiny additional vent hole in the cap just above where it seals. Its rather hard to describe where it is. But I could send you a picture if you want. [email protected]
On Feb 8, 10:33�pm, Dennis Hammerl <[email protected]> wrote: > If it aint broke, don't fix it. Happens again ? Then we'll chase it. > > ________________________________ > From: "[email protected]" <[email protected]> > To: [email protected] > Sent: Mon, February 8, 2010 12:29:49 PM > Subject: [Nighthawk Lovers] Carb Issue > > Dennis, > > You asked for a ride report. On Sunday, I rode for about 5 hours, with long > stretches at 75-80 mph. The bike performed just fine, no surging, no > suffocating, even though I followed the same route as the time it did so. The > only difference was the weather was cooler this time, about in the 50s average > all day. �Could cooler air lessen the problem of a clogged carb > vent or do these things sometime "fix themselves"? � �Any > suggestion for I should try or test next? > > Thank you, > > Jay S > 92 NH750 > South Florida > > �Topic: Carb Issue > [email protected] Feb 05 11:14AM �-0500 ^ > > Dennis, > > Thanks so much for the quick reply and the good and highly �detailed > advice. As much as getting the steps to take, I appreciate �learning the "why" > behind something malfunctioning. > > To answer your �queries, first, my bike is not a California model. Second, > I tried what �you suggested, leaving the bike parked overnight with gas cap > open and �petcock on, and in fact, it started normally the next morning, no > flooding. I also noticed a slight whoosh when opening the gas cap after > about a 15-20 minute ride. Both, if I read your note right, are �indications > of a clogged gas cap vent. If so, what is the fix? And can I �do it myself? > I have not yet tried a long, high-speed ride but will on �Sunday and will > report what happens. Thanks again. You are a fantastic �asset to this > board. > > Jay S > 92 NH750 > 85K+ miles > South �Florida > > Dennis Hammerl <[email protected]> Feb 02 09:47PM �-0800 _^_ > (mip://01cdae38/default.html#digest_top) > > Ok, OK... now slowly, very slowly, let's look at your �problem. Or rather > two problems. And yes, they both can be related. (we'll �see that later) > First off, is this a California bike ? The answer makes �for a different > approach. The highway deal can be a function of thermal �failure of the > ignition > (it gets hot..duh) That one is harder to trace out �so let's go with a more > common problem (there really are no "common" �problems with the late model > 750's) I would suspect that there can be a �fuel starvation problem at highway > speeds. Normally it doesn't take very �long for a fuel starvation problem to > show up (just a mile or so) if it �has a restricted fuel supply. (kinked > hose, etc) Yes, opening the throttle �more makes it worse. Now if the tank > vent is obstructed it can take longer �to starve the engine. (here's where > California bikes are different) If the �fuel supply is inadequate, it can run > well at low speeds and "run out" at �higher ones. An inadequate vent > would just make it work longer than if it �was blocked completely. So much > for deep thinking. (hey, you have to �sometimes) What do you do ? For > starters, leave the tank cap open �overnight with the petcock "on" and see if > it > starts OK. (I always turn �mine off... ) Then report back. In south Florida > it gets hot (whew) and a �bike in a garage or shed (I won't do it again) will > cause the tank vapor �to expand and force the fuel past the needle valves. > See the relation now �? A blocked / obstructed vent can cause carb flooding > and fuel �starvation.(different times, different causes) Opening the cap at > highway �speeds is not a great idea but try it and see if it clears up the > running. �If you go out for a ride and open the cap before you start it and > it goes �whoosh... TaDa ! > This is just a place I'd start to look for your problem. �85K is a ton of > miles and there may something other happening, we'll see. �I go with simple > stuff before I dive into the complex. Get back to me with �what you find. > Remember that if this isn't "it", that's just something to �cross off the list > of possibilities. > > ________________________________ > From: �"[email protected]" <[email protected]> > To: �[email protected] > Sent: Tue, February 2, 2010 7:37:44 �AM > Subject: [Nighthawk Lovers] Carb Issue? > > I'm hoping the �experts on this board (and hopefully Dennis H) can give me > some guidance �on a problem with my '92 NH750, with over 85K miles. > > On one �hand, the engine floods when the bike is parked, leading to hard > starts. �Turning off the petcock between rides makes this manageable. > However, now �there's another issue. On highway rides, after an hour or so > at 75 > MPH, the bike suddenly starts to lose power as if it's starving for fuel, > surging and suffocating. The more I open the throttle, the worse it gets. > But if > I slow up to 60-65, it recovers and then is fine. Don't know if �the > problems are > interrelated, but the local tech doesn't want to do a �carb teardown to > check it > out. Says it would be expensive and there's �no guarantee he'll find what's > wrong. I love this bike and think it has �many more miles to give. > Any help would be appreciated. > > Thanks so much in advance. > > Jay S > South �Florida > > Dennis Hammerl �<[email protected]> Feb 05 08:00PM -0800 ^ > > The question of it �being a California bike is because they don't vent at the > cap. The venting is �complex and would make us look into that system and not > the cap. In your case �the cap seems to be restricted. Replacing the cap is > the easiest fix. They are �somewhat pricey. The restriction can be many > things; crud, swollen gaskets, �rust, etc. They aren't meant to be > disassembled and as such there are no �individual parts for a cap. You can > try to find and cure the problem but very �often it's a swollen gasket caused > by the ethanol content of today's fuels. �Let us know how your long ride goes. > -- > 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]. > For more options, visit this group > athttp://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]. For more options, visit this group at http://groups.google.com/group/nighthawk_lovers?hl=en.
