An excellent question. I haven't had to deal with one of those in years. Since you seem to be quite able to perform changes, I might make a few suggestions. First off, are these VB2FB carbs ? No 400 / 450 really ran all that well off idle till engine temp came up. So replacing with some other carb pack won't be much of an option. You increased the fuel at slow speeds by 2%, which isn't very much. Another 2% (#42) might help some but you will encounter a point of diminishing returns quickly. The problem being that there is insuficiant air speed at low RPM's to atomize the fuel and carry it in. Two factors are at work here; to provide performance the carbs are rather large (throat area which causes low air speed at low RPM) and the compliance with EPA for emmisions (lean)... These are not good companions. It is essential to have all the air-box parts in place (with filter) for one of these to run. To achieve "driveability" I prefer to attempt to increase air speed rather than simply jet larger. Believe it or not, smaller carbs make one of those fun to ride. Let's not go there. I'll do some research and see what we have done in the past to correct this problem.
--- On Fri, 10/2/09, JFTdiesel <[email protected]> wrote: From: JFTdiesel <[email protected]> Subject: [Nighthawk Lovers] `86 450 carb question To: "Nighthawk Motorcycle Lovers!" <[email protected]> Date: Friday, October 2, 2009, 10:53 PM I picked up an `86 450 this spring for my wife (newbie rider and lovin' it!) and have put about 1,500 miles on so far (11K miles at time of purchase). I went through the fuel system very thoroughly and am confident that all is working as it should - mostly. But, I do not seem to be able to get rid of an off-idle cruise stumble regardless of the gear or speed. Part throttle or more and rolling-on throttle is fine. I brought the pilots up 1 step to a 40 which improved a few things but not this stumble. Low idle is perfectly smooth, vac is 20"+, sync is perfect, plugs are lean(ish) but clean. The little bit of research that I've done says that these `86 carbs are purposely very lean. I'm fairly knowledgeable about carbs and carb tuning so my question is this, is it worth the effort to "un-lean" these carbs or should I just swap the `86s out for an earlier set (or something else altogether) and go from there? Any links/resources or known procedures, etc. would be greatly appreciated. Thanx! JT --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
