carb troubles

hi i am new to the site and to hondas. just purchased a 1985 interceptor 500.. bikes in good shape but the carbs came in a million pieces..lol i have finally got them together but my problem is i need a base setting for the pilot jets i no every bike is different but it would be nice to have a starting point.. any help will be greatly appreciated.. thanx anxious to ride this baby

 

According to the Honda service manual, base setting for the pilot screw on an '85 is 2 turns out.

 

I've found between 1 1/8 and 1 and 1 1/4 turns is where all my Honda V4's are happy.

I find two turns to be about like the choke being on all the time.

 

The screws have small manufacturing variations, so what's fine for you might not be so on another bike. That's one reason why the factory-recommended setting is only a starting point for any final adjustment.

 

That's really interesting, I think the manual for the 86 vfr700 says 3 turns out or it might have been the consensus on this forum. Anyway, I'm personally afraid to go less than 2 turns out for fear of it running lean and causing engine damage. Maybe my fears are unfounded.

How did you determine the correct pilot screw adjustment?

 

Side bar, I had a Virago 250 that would not run worth a chit withoot the fuel mixture screw turned 3 turns oot, may have even been 3.5

 

My Virago 700 was 3 turns out, too, but those are completely different engines, carbs, etc... so I don't think we can compare them to the V4.

Now that I think about it, you'd need to sync the carbs before fine adjusting the mixture screws. It's easy to have one butterfly closed too much and the cylinder not firing at idle. I had that happen to me. I kept adjusting the pilot screw and it never had an effect on that cylinder. I even took the screw out completely and it had no effect. Once I did a real sync, all cylinders were firing at idle.

So I guess we should bench sync if they are off, set all pilot screws to 2.5 turns, then a real sync, then fine adjust the pilot screws. After that, maybe a final sync?

 

Then another bench sync, pilot adjustment, vacuum sync, bench sync again, 2 vacuum syncs, another pilot adjustment, then take off your PAIR and repeat all these steps over again... twice. This i my experience.

 

^and did you change your thermastat? If not, you may be in for another carb/off/carb/on, kinda like wax-on-wax-off. And don't forget to tighten those four small radiator bands that go to that housing.

I know a Yamaha Virago is like comparing apples to oranges to a Inteceptor, was just making a comparison aboot how critical a turn or two makes. Cheers.

 

Why? You make no sense. Bench sync only needs to be done once to get bike running. If you have to keep pulling carbs off, your not cleaning them thoroughly the first time. If you pull them a second time for additional cleaning, no bench sync is required.

Thermostat has no bearing on carb tuning. You just want the carbs hot like normal riding.

 

Skippy, very obvious t-stat has no bearing on carb tuning Was casually mentioning to whom ever thought it was important; that when you have the carburetors off a generation 3 bike, it is prudent to change the t-stat because its buried in the v of the motor, at least it is in ours (gen3) bikes. You generation, I am not familar with. Far as re-bench synching them when they come off? Its personal preference really, depending on how badly you man-handled them, really, what does it mean to do it again. If you do that then, your setting your self up for another session with the manometer.

I feel like I am having a conversation with my wife, yah know? Sheesh...:tongue:

 

I bet your a Leo.

 

... 6 bench syncs followed by 215 pilot screw adjustments, then re-jet, put PAIR back on, cuss, sell bike, buy mini van.

 

Ridervfr, you mentioned the thermostat, not a "skippy" person. Are you calling yourself that? That's confusing.

(2nd gen bikes have easy access to T-stat)

Are you asking me my Astrological sign? Let's stay focused here.

If Commrad is out there, I'm curious as to how you set your pilots. I've never heard of such a lean "ish" setting that wasn't from the factory.

 

Yeh, I know the t-stat is on the side of your gen bike. Point was, on "our" bikes, its buried in the Vee, and is easier to replace when carbs are "oot."

You sure your not part German? Yep, I axed you your ass-tro-logical sign, which you chose to ignore, its kewel and all. Just trying get a grasp the situation and all, its all good especially if your riding a vee-four :hippie:

As far as "commrad" goes, Its a Sputnick-Mutnick situation, what does it matter (space race is over)/??...Insert "Jason" instead of "skippy" oh-tay? Can it be any more abstruse?

 

I've tried my pilot screws at 3 turns out and it rode pretty good, but had a habit of not returning to idle nice and quick. It had a lag after a quick rev. Warm idle smelt richer than usual and my fuel consumption was a lowly 29 mpg.

I've tried 2, 2.25 and 2.5 turns out and they all had a rich smell at idle, but a snappy throttle response and returned to idle quickly. At 2.25 turns out I got 37 mpg average. No freeway use, just running the streets and hot dogging it. The usual.

I settled on 2.5, just because I was afraid to have it too lean.

Currently, on a warm day I choke it and it cranks fine, but after a minute or so starts running rough so I have to turn the choke off. This also drops the revs and since it's not really warmed up it barely idles at around 700-800rpm. Plus it still smells really rich at idle.

Also, if I do a slow cruise at 3,000 rpm and then twist the throttle to take off it sometimes stumbles for a second and then takes off. Also, when I'm cruising the freeway in 6th gear at about 6,000 (very common) it has little to no throttle response. I need to go down a gear or 2 to get the revs above 7k and then she pulls strong. It just seems kinda flat between 5500rpm and 6500rpm. I experimented by adding a little choke on the freeway to see if it was maybe lean at 6,000, but it only got worse.

I'm gonna try setting the pilots to 1.75 turns out and just see how she responds.

 

Not easy to find a tach sensitive to 50 rpm + or - but idle drop procedure as outlined in FSM is the way to go. As an alternative, try this: with engine warm, turn each mix screw IN until that cyl cuts out at idle. That sets your starting point for experimentation. Subsequent moves of the screw are +1, +2, or +3 from the screw position established at the cut-out point.

Jason, u know that idle mix screw settings have no connection to problems at 5500-6500 rpms. You don't have stock exhaust, right ? To cure that flat spot, try shimming up slide needles. On a warm day the choke should be off after about 15 seconds, and you need to use the idle speed adjusting screw to set a faster warmup speed, not the choke.

 

Okay, so out of curiosity I set the pilot screws to 1.5 turns out. It ran okay, but you could tell the bottom half of the rpm range was kinda weak and it would stutter or buck occasionally. I don't know how Commrad was successful with several V4's at 1 1/8 to 1 1/4. My bike does not like that.

I then went the other way and did 3 turns out. It ran great in the lower half of the rpm range, but the flat spot in the middle was still there. So it looks like the shimming the needles is next.

Squirrelman, I've got factory exhaust cans, but are modified to flow more freely. So it's louder and less restrictive. Do you think that lack of back pressure is what's causing the 5500-6500 flat spot?

It might be easier to restrict the exhaust back to stock levels, or at least a 1" diameter hole outlet, to see what effect it has.

(my filter is paper and airbox is stock and all stock needles and jets)

 

Yeah, lack of backpressure is likely a contributing cause, but it should be curable with jetting and needle shims and alot of experimentation.

 

I added some restriction to the exhaust and now at a steady 5500 or so I can give it half throttle and it has power. It takes off, but if I give any more throttle the power drops off. So I'm gonna restrict it a bit more and see what happens.

I figure too much backpressure will start to hurt the top end of the power band, but so far, so good.