Vacuum gauges will not show slide function. They are dependent on throttle plate opening. Remove the slides, replace the caps and you can sync the carbs at idle. I prefer to watch them. Whatever. The jet sizes will tell us a lot about the rest. (70-120 ?) The early models of that bike (pre "86) used a more complex carb with more stages. Two secondary. Early editions of the '86 used 120 mains, later 70. That alone will drive you mad... Did you remove and clean the needle jets ? I just checked a site I use and they indicate 125 as mains and 40 for pilots. So yours is an early '86. CA model ? or 49 state ? Transmission whine ? What gear or all ? I'd need a better reason to open one up. Or a glaring noise. Honda transmissions are noisy..period. Straight cut gears and chains just make noise. It would take a shiffting problem or a jump out-of gear to make me look inside. Both of my 700's make a whine in 3rd.. so what ? Everyone I ever rode did. And, it is possible to overtighten the cam chain on one of those (400 / 450) . Have you checked the primary chain tension ? Lots to do.
--- On Sun, 10/4/09, JFTdiesel <[email protected]> wrote: From: JFTdiesel <[email protected]> Subject: [Nighthawk Lovers] Re: `86 450 carb question To: "Nighthawk Motorcycle Lovers!" <[email protected]> Date: Sunday, October 4, 2009, 12:10 AM Hi Dennis, I inserted my responses below ###. On Oct 3, 8:04 pm, Dennis Hammerl <[email protected]> wrote: > OK, a ton of confusion exists with these. What do you have for main jets ? 70 > or 125 ? ### Mains are still stock 125s. The problem range is as you describe, partial throttle. However, the slides are very much a part of the fuel feed at that RPM. Can I assume you had these completely apart ? Any chance of having exchanged the slides / pistons ? AND, possibly rotated the caps ? The caps should read from the riders position. (embossed lettering) ### I did completely dismantle the carbs but did not separate them from the rack. My "boys" give me a hard time about my meticulousness (that even a word?) when cleaning carbs, or building an engine, but the results are usually worth the effort. Having said that, this motor sat for almost 18 months and was not prepped for storage, so the carbs were a train wreck and there may still be some clog or restriction hidding in there somewhere. I've SeaFoamed her 3x thus far with no change in behavior. I usually do a good job of keeping the parts sorted, but there is always the possibility of getting it wrong. I can easily confirm the cap orientation, and the slides worked freely by hand after re-assembly. >A possibility is the slides not responding till you apply a ton of force via >pressure diff. The problem you are encountering is not a common one. Most >often, the glitch is right off idle when pulling out. Please confirm above >before we proceed. Check for scaring on the slides. The fit of the slides and >caps is a hand selected one and very critical. Under the caps are some >passages that bleed air and should be checked for open. ### The off-idle pull stumble is there too, but diminishes to virtually nothing as the motor comes up to temp. But I suppose I could apologize to the clutch, hook up the vac gauges and power break it; the gauges should tell me if the slides are working in sync. It'll be a few days before I can get to do that though. The carbs used on the '86 are quite different from others. ### So I gather. Hence my earlier question of whether to keep messing with 'em or is there a more "plug-n-play" carb swap that's been sorted out. We're running out of ridding season here and the motor is coming off the bike this winter (got a transmission whine to sort out) so I'll have plenty of time to work this carb issue. Ya know, it just occurred to me that I don't think I ever checked the timing on this motor - DOH! That my friend will be job 1. But I'll confirm the other info you asked for at the same time and get that back to you. Talk soon, JT > > --- On Sat, 10/3/09, JFTdiesel <[email protected]> wrote: > > From: JFTdiesel <[email protected]> > Subject: [Nighthawk Lovers] Re: `86 450 carb question > To: "Nighthawk Motorcycle Lovers!" <[email protected]> > Date: Saturday, October 3, 2009, 12:31 PM > > Hi Dennis, > > I appreciate you looking into this a little for me. To answer your > question, this bike has one each a VB2EA and a VB2FA (single LH accel > pump w/ a cross-over tube to the RH carb). And to clarify the > behavior a little more, the stumble seems to be independent of RPM; > 3rd gear 3K RPM 35 MPH or 5th gear 6K RPM 60 MPH cruise, the stumble > is there until you roll-on power. So, my thinking a this point is > that the stumble is tied to throttle plate position (just off idle and > approaching part throttle) and thus working solely off the pilot > circuit. And playing with the idle screws seems to only affect the > low idle. I Hope this is useful info for you. > > And why not talk about smaller carbs? The way this bike is going to > be ridden, it does not need max top end - it's primarily a commuter > bike, so great low end / mid-range throttle response/power is really > the goal here. > > JT > > On Oct 3, 12:27 am, Dennis Hammerl <[email protected]> wrote: > > > 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 -~----------~----~----~----~------~----~------~--~---
