Dual Weber IDF 40 Setup - What's it worth?

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Doing a bit of reading, I'm not so sure the higher RPM issue I'm having is a Progression issue. The mains are coming in much lower - like starting at 1500! So, I'm starting to think it's more likely to be accelerator pump related. For sure, I'll need to scientifically sych them. For now, I did the "idle drop" thing with mixture screws and that helped quite a bit. Still...

(I'm having fun with this beast).
 
yes id say fstsix is right about starting with idle and getting it right ....0n my bike ...witch has no choke at at all either ...there was a certain dial in i got finally that required no choke and delivered great mpg also ....seems with the idf webers against the proggressive webers 2bbl like mine is air feed ...idf flow much bigger air than the progressive weber 2bbl do ....this really means nothing they both provide all the oldwing motor can handle at wot....this it where velosity stacks might turn out to be required on your build ....the longer the tube equals less more structured air coming in carb ...even on my carb i fiddled with my own version of velosity stacks ...in the end with me the air box kind of over ruled the stacks i use ...it was interesting how different the carb acted with no airbox and stacks on ...but i didnt want to run with out and airbox....but did fine a nice taller filter than what i had that seemed to flow much nicer than the pervious one i had ....all things can have an impact especially on the air side ...as this is the biggest part of a good charge and idle being the hardest thing to dial in right ...motor bearly running ..things have to be right there ...watching with interest
 
Thanks for the input, Joe. Glad to have you along for the ride. For sure this is not a path many will take, so not a huge amount of interest in the conversion.

But, for those who are tuning in, while I'm waiting for my fatter idle jets and synchrometer (found a cheaper Empi version), I did make some positive progress today. The erratic idle and lazy return to idle were greatly improved with the addition of a weak auxiliary throttle return spring. Still some hanging, so I might try a slightly stronger spring. Not really much else to do for now until the jets and synch'ing tool are on hand.

I did take a longer ride today. There's still a solid stumble - both off idle (jets) AND when cracking the throttle between 3 and 4k RPM. Here, the accelerator pumps are all squirting, but there may actually be TOO much squirt. I have the accelerator pump discharge valve (by-pass) set at zero, so the pumps are max'ed out. Could be too much.

So, this is going to take a while to get just right, but HOLY HELL. Today's ride served to confirm for me that when you kick this girl in the pants now and get past the bog, she sh*ts and g*ts. Absolutely plenty of air moving through this four cylinder pump.
 

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Warm it and set idle as close 1000 rpm as you can get. Adjust each air mix screw one at a time to the highest rpm possible. Rest idle after each one. Do it twice. Adjust each accelerator pump to the lowest setting possible. See how it runs that way. Maybe open the low side air jets a bit if it still bogs. Oh and check for air leaks first.
 
if the excellerator pump adjustment can be done id do it now ..see what happens ...this will go a long way in figuring out where the idle is at ...im not totally convinced its to lean ..also you can turn throttle slowly and this also cuts accellerator pump input...just dont get up changing jets as the problem ...many times it not that simple ....this is not matched up stuff ....man did i ever figure that out with my bike ...it was anything but jet and go
 
Wow that is really a Bad A$$ looking Wing ! You fatten up that Idle circuit your idle will not hang like a vacuum leak and you feel the Grunt off throttle , All my bikes have had at least one step richer for Pilot jet , Much better cold start and Way more grunt mid throttle. Hope you get your jets soon...May the Big Brown truck be there soon lol, Had a Weber DCOE 45 Sidedraft on my Turbo VW Sandrail back in my Glamis days , Same thing first time out just bolted it all together and it had such a bad hesitation no matter what Main jet i put in.... had jet drill kit and opened up the Slow jet and Night and day !
 
[url=https://classicgoldwings.com/forum/viewtopic.php?p=200914#p200914:12frt2oc said:
joedrum » Yesterday, 8:20 pm[/url]":12frt2oc]
Gee Greg no belly there ...you been a bit rich on fuel over the years LOL...great pic ...sand rails were fun ..they were the most fun thing you could do to a vw set up
Hahahaha , Ya know what i mean when i say that CBX is like riding a Popsicle stick ! :smilie_happy:
 

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Well Ladies and Germs, I do have another incremental installment report. Guess it'll be a series of small victories rather than a single "eureka!" I expected as much.

But, my one-size-larger idle jets have aroven. And I am happy to report that the motor really likes them and has responded very positively. It actually idles now. And, strangely, even though there are now "larger" idle jets in place, the motor smells like it's running cleaner at idle. I cannot explain that, but the nose knows. Even better, the bog has been greatly reduced. Notice I said reduced, not eliminated. There's still a slight hesitation when getting on the throttle from cruising altitude (say still between 2500 and 3500). Definitely better than before. Does that mean even fatter jets would do better ??? Hmmm. A guy could go broke tuning these danged things. This might be where drilling one of these sets out might be an option.

So, I've only touched the idle jets. I am a firm believer in doing one thing at a time. Now, I'll probably start fiddling with the accelerator pump to address the bog. The stroke can be adjusted, the actual pump jet can be re-sized, and there's the by-pass valve that is currently effectively blocked - meaning all the juice goes through the pump jet. I still think it's a little too much. That will be discussed in an upcoming report.

My airflow meter (synch gauge) is still on the way, which is a good thing. While it does idle steadily, there's some primary chain noise that simply wasn't there with the well-tuned OEM rack. The barrels need synchronizing badly.

Anyway, I can honestly say it's running well enough now to go pretty much anywhere. Very streetable just as it is. And, oh yeah, it scoots.

I think I'll start thinking about picking up a new pair of belts and getting the early cams installed. Just for fun.
 
I went through this also ..how many turns out on your mixture screws ? and are your spark plugs light brown dark brown white or ..picture please , You can richen your idle jets to the point of fouling your plugs , I found once you get so rich It will have lots of grunt but plugs will start missing and runs strong before that point . and that depends on turns out on mixture, you should try to turn your mix screws out more to richen and see if it darkens plugs , If not it will need larger Idle jet ...hope this makes sense ? 90 % of all cruising is in the Idle circuit, You got alot of Air now check a plug
 
Thanks guys. This reminds me of the old Holley days. But the Webers are such a pleasure to work on. I'm trying to balance my tuning sessions with a long list of "honeydew" items. I'm gonna wait until my flowmeter comes in before I do anything else. But I tend to agree with the Fstsix. I think even fatter low-speed jets will put me on the path of righteousness.

Thanks again guys. I used to fancy myself a pretty good carburetor guy. But Webers have so many variables, it's easy to get tripped up.
 
the early cams will change everything ...the cams it has now are the mildest honda ever made and the cams you are wanting to put in are the most aggessive they ever made ..if that is what the plan is ...id put the cams in now ...dialing in the 78-79 cams is just waste of time ...in my opinion
 
[url=https://forum.classicgoldwings.com/viewtopic.php?p=200948#p200948:1gh59z2g said:
joedrum » Fri Mar 02, 2018 9:11 am[/url]":1gh59z2g]
the early cams will change everything ...the cams it has now are the mildest honda ever made and the cams you are wanting to put in are the most aggessive they ever made ..if that is what the plan is ...id put the cams in now ...dialing in the 78-79 cams is just waste of time ...in my opinion

Thanks Joe, but dang I didn't want to hear that. My thinking was that the early cams' major difference is their breath (longer duration and mild lift increase) impacting on the high end. I haven't dinked with the mains yet - and I would expect that to be where the major difference is with the cam swap. I could be wrong. It happened once before. 1987 I think (when I married my first wife). :nea:
 
well your sort of right in how it works and where ...the lift on the two cams are about the same ..but the duration on the 79-78 cams is like nothing ...the supercharger boys like the mild cams cause they really shut the door down and they can get the boost to hang in there longer ...as the oldwing motor is like not even close to a supercharger set up in reality..the early cams would present problems quick for them ...but on the weber set up this goes the other way ...the early cams will be able to the advantage of the bigger weber carbs and flow ..and this actually is true all the way down to idle ..once dial in right ..in my opinion
 
Well, found a couple of issues - one my doing, the other from the PO. (Actually my fault too and I'll explain). Hopefully, once completed, I'll be in a better place - although the place I'm in now is not too bad.

One carb came "fully rebuilt" with the correct jets and venturis. The other needed everything. I bought kits and refreshed both - except for the accelerator pump diaphram on the PO built unit. I left the red rubber diaphram he put in there. Turns out, that side had a signficantly weaker "squirt" from the pump. My first assessment didn't pick up on the difference. I'll blame poor light in the garage. There was also a large delta in the fuel levels in the bowls. My fault. I balanced the float heights.

...but in the process of replacing that pump diaphram, the danged spring launched itself to parts unknown in my garage. Gone. Wasted 30 minutes looking for it. Sheesh. Shuts me down. I have one on the way - supposedly to arrive tomorrow. Fingers crossed.

Meanwhile, I did grab a video just before pulling the carb for addressing the pump. At least it idles. It's not cold here, but not fully warmed up, either. The flowmeter makes dialing these things in a breeze. I still have all air bypass screws closed. There's a slight imbalance barrel to barrel on both sides, but not much. Tweaking those will get it close to perfect. It's close now.

Getting there. Shoot, this is actually kinda fun!

[video]https://youtu.be/AnHnokR68DA[/video]
 
That sounds pretty darn good! :salute:

Curious, are you going to be hearing a lot of intake noise with the open throats right under you there?
 

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