View Full Version : Carb adjustment
Hazwan
10-17-2011, 03:11 AM
I'm running out of ideas here guys. I can never get my carb adjustment to be 99% perfect (N) It always runs lean, at least I could tell from the exhaust fumes. How exactly do you get the idle mixture/fuel level screw adjustments done on a stock EL1 carb? I did every possible ways that I could based from my experience with carbs but I'm not sure if I'm missing something here.
And yes, I've ruled out vacuum leaks. aaaaand I'm not sure if this gonna effect this as much but I've deleted the manual choke since I never used them, as well as knife edging the butterfly plates. Unless I did screw up with the process then I don't see how else I'm gonna run this lean!?!!!111 :dunno:
Dr_Snooz
10-17-2011, 10:14 AM
The idle mixture screws are just that. They adjust the mixture at idle only. Once you crack the butterfly, they do nothing. If you're running lean down the road, you need to adjust your jets. I'm used to American carbs though. It might be different on Hondas. If memory serves, the float adjustment is exceedingly important for Hondas. Have you checked your levels on the sight glass? If the carb doesn't have sight glasses, throw it away and get one that has them. It might also be time for a rebuild if the carb is really old. Other than that, you're basically coming to the realization that all of the automotive world did in the '80s: carbs are never 100% right. If you want that, you have to go EFI.
Edit: What are your symptoms exactly? Are you getting hesitation with steady speed driving? Hesitation off the line? Rough idle?
2oodoor
10-17-2011, 11:04 AM
it is important to back off the curb idle adjustment as much as it will go and still allow the car to run.
That is the one that is one that the throttle linkage goes to. As long as it is pulling on the throttle, the carb is not running thru the idle circuit.
Note that some cars just won't run at all with that backed all the way off, so you do have to give it some opening but certainly not much because the idle circuit pulls idle air from underneath the throttle plates (butterflys)
Setting base ignition timing kinda goes hand in hand with that process because once you have the throttle idle screw backed down the engine runs slower , so yes if you notice the base timing always has an rpm spec as well as what BTC figure it requires.
Then you adjust the idle mixture screw which is the other one. You will have to go between the three basic settings a few times to tweek it up to where it needs to be.
Having the choke diconnected could be a reason why it runs lean sometimes, there is supposed to be a choke angle setting too that is pre engineered with the carb itself. This and the venturi size, and booster configuration all intersect as the engineered carb.
Of course you can run it like you have it but if you want to be picky...um lol
Hazwan
10-17-2011, 02:50 PM
The idle mixture screws are just that. They adjust the mixture at idle only. Once you crack the butterfly, they do nothing. If you're running lean down the road, you need to adjust your jets. I'm used to American carbs though. It might be different on Hondas. If memory serves, the float adjustment is exceedingly important for Hondas. Have you checked your levels on the sight glass? If the carb doesn't have sight glasses, throw it away and get one that has them. It might also be time for a rebuild if the carb is really old. Other than that, you're basically coming to the realization that all of the automotive world did in the '80s: carbs are never 100% right. If you want that, you have to go EFI.
Edit: What are your symptoms exactly? Are you getting hesitation with steady speed driving? Hesitation off the line? Rough idle?
No sight glass on mine :thumbdn: How do I make sure that the level is correct then? The car runs really rough during idle and there is a slight hesitation off the line, but not too bad. Exhaust smells bad when its idle too.
it is important to back off the curb idle adjustment as much as it will go and still allow the car to run.
That is the one that is one that the throttle linkage goes to. As long as it is pulling on the throttle, the carb is not running thru the idle circuit.
Note that some cars just won't run at all with that backed all the way off, so you do have to give it some opening but certainly not much because the idle circuit pulls idle air from underneath the throttle plates (butterflys)
Setting base ignition timing kinda goes hand in hand with that process because once you have the throttle idle screw backed down the engine runs slower , so yes if you notice the base timing always has an rpm spec as well as what BTC figure it requires.
Then you adjust the idle mixture screw which is the other one. You will have to go between the three basic settings a few times to tweek it up to where it needs to be.
Having the choke diconnected could be a reason why it runs lean sometimes, there is supposed to be a choke angle setting too that is pre engineered with the carb itself. This and the venturi size, and booster configuration all intersect as the engineered carb.
Of course you can run it like you have it but if you want to be picky...um lol
Thanks, I'll give it a try but I can't imagine the choke, even when its fully open is gonna effect the mixture this bad :o
lostscotiaguy
10-18-2011, 01:58 PM
I feel your pain brother!! I'm in exactly the same situation with MY carb.
Good luck to you! If I had the resources I'd switch carbs and weld an AFR sensor into my exhaust manifold! people tell me to switch to an 82 or higher carb (for the float windows) but with all the crazy anti-smog stuff on mine, I don't think I can just bolt one on and go. There's other compnents on the newer model that aren't on my 81. Lemme know how things work out for you! I've set my floats according to the common instructions found online for wet adjustment and it worked the way it was described...but as for setting the idle mixture I'm not having much luck. I keep tuning for the highest vacuum and yet it still doesn't seem to be running right. If you DO finally get it tuned right, can you tell me what steps you went through? Good Luck man!
lostscotiaguy
10-18-2011, 02:21 PM
Oh, as for the wet adjustment, if you hadn't seen the instructions elsewhere I'll summarize:
Dry adjustment 1st:
http://img231.imageshack.us/img231/8605/scanb.th.png (http://imageshack.us/photo/my-images/231/scanb.png/)
Uploaded with ImageShack.us (http://imageshack.us)
Sorry about the top of the page! The grease on it ruined my scan, so I'll redo the text that's blurry:
Step 1:Bowl cover inverted, then turn up to the vertical position with float arm pins to the top. Float resting lightly on needle (which is spring loaded) DO NOT compress spring loaded needle.
If the image STILL isn't readable, let me know...I think I have another GOOD copy of it somewhere.
Wet Adjustment:
http://hubcap.clemson.edu/~wstef/carb.html
I followed these instructions and they DID work. However instead of waiting just 15 seconds between each adjustment I waited at least 30 seconds. When you're doing this adjustment (the part where you're backing the screw out) you'll know you're pretty much at the right spot because the idle will rise up very high and then it will stumble till it stalls out. Remember too, that after you adjust the float screw back in 3/4 it will still be flooded as hell when you go to restart it... I'm probably stating the obvious with these posts but I'm just tryin to help!! :deadhorse:
I would kill for float windows.:violin:
2ndGenGuy
10-18-2011, 02:25 PM
Yeah if you wanna switch to an 82 carb or newer, you either gotta de-vac the whole thing or bring across all the vacuum lines and black boxes for it to work right. And the de-vac probably won't ever run 100% either. Lots of work for very little benefit. In Hazwan's case, he could probably get a non-cvcc, non emissions carb from an 82 or newer over there. But he'd be better off finding a bigger, different carb from another car... like some sort of Holley or OEM Weber or something like that...
lostscotiaguy
10-18-2011, 03:03 PM
"you either gotta de-vac the whole thing or bring across all the vacuum lines and black boxes for it to work right."
Thank you 2nd Gen! That's what I thought...people just kept telling me just to swap it over but every 82 and up I've seen was VERY different when it comes to black boxes,etc.... I thought I was just being stupid! Being in California, I'm still intrigued by the idea of just getting a Weber and hopefully finding a smog guy who's not very observant. I'm somewhat sure it WOULD pass the running inspection, just not the visual....Maybe I could slap a weber on and alter the factory filter cover to fit, just for looks?
Hazwan
10-18-2011, 10:07 PM
Will a carb from a 2.5g fit?
2ndGenGuy
10-19-2011, 07:55 AM
Probably if you can make the right adapter plate. But if you're gonna do that, might as well get a carb from a 3gee. It's a lot bigger than the 1g carb, it has the windows, and there are a lot more of them out there, and they are going to be bigger and might give your car a nice little performance bump.
carotman
10-19-2011, 10:19 AM
Is there a float drain screw? You can put a clear hose in the bleed screw hole and use it to measure the float level.
Just like this:
http://www.justanswer.com/motorcycle/27eza-yamaha-atv-1986-moto-200-what-carb-float-level-setting.html
lostscotiaguy
10-19-2011, 11:17 AM
Is there a float drain screw? You can put a clear hose in the bleed screw hole an...
Unfortunately not...there IS a tool that Honda had that was built to check the float levels on these carbs, but the tool is no longer available, and in fact I doubt one even exists ANYWHERE! LOL I don't think any dealerships would even have one stashed away somewhere. I'd be happy to even SEE one (for curiosity's sake) as I've never even seen a picture of one, just a drawing.
Hazwan
10-20-2011, 02:32 AM
Bleh the car still would smell horrible when its idling no matter what I did. But messing around with the float level did help with the stumble while going WOT from a dead stop, as well as smoothing the idle a bit. But the smelllllllllll :chainsaw:
I guess I'll just live it for now while I save up for the bike carbs. Woops I said too much already :naughty:
2oodoor
10-20-2011, 03:47 AM
Sounds like you found the root of the problem.
Since we are going to have more and more problems with carburator compatable fuels in the future....
I would just find a Weber 32/36 to put on the car. You will need something simple to service with parts readily available.
It doesn't have to be a Weber, but any aftermarket style carb that is still being sold as new would have parts available.
The accelerator pump diaphragm has steel in it and will be prone to growing rust in it that will eventually cause the diaphragm material to collapse. I think I would do the power valve hack mod to eliminate that extra part as well.
Dr_Snooz
10-20-2011, 07:05 AM
No sight glass on mine :thumbdn: How do I make sure that the level is correct then?
I wasn't able to get it adjusted. I ended up having to throw out the carb and swap in a junkyard replacement. That was on my '76.
My '82 had the sight glasses. I was able to rebuild that one successfully, but only because of the sight glasses. Your problem could be a number of things. You could have a needle valve leaking, a float sinking, a gobbed up jet or something else. My '82 carb failed because of a sunk float. Because I had the sight glasses, I could see the bowl going from fully flooded to completely empty with only a slight adjustment. If I didn't have the sight glasses, I would have thrown that one away too.
people tell me to switch to an 82 or higher carb (for the float windows) but with all the crazy anti-smog stuff on mine, I don't think I can just bolt one on and go.
It was probably I who encouraged you to swap. It was more of an abstract possibility than a concrete action plan. I know that my '82 carb looked an awful lot like my '76 carb after you pulled all the peripheral garbage off. After you removed all the solenoids and vacuum diaphragms and such, the float bowl was essentially the same. I never compared the two side by side, so they could be different enough to make it impossible. My hunch is that that isn't the case though.
If I still had a carb, I would buy two junkyard carbs. One that matches mine, and one with the sight windows. I would attempt to rebuild the one with the sights and I would mix and match components from the two until I got something working. To do this, you'll have to figure out what all the controls do and how they operate, but no one ever said keeping an old car running would be easy.
I posted a write-up on getting through smog here (http://www.3geez.com/forum/showthread.php?t=76568), based on my experience getting my truck through a California smog check. I encourage you to read it carefully as there is a lot of good stuff there. I'll summarize some points for you though. Basically what happened with the Keihins was that California was becoming increasingly stringent about smog every year during that time. As the regulations became more stringent, Honda bolted more stuff onto the carb. For example, they found that cars dumped a lot smog when they shut down and dieseled, so they bolted on a solenoid to keep that from happening. A newer carb is, as a rule, going to have more smog controls on it. Here's the deal though: the California smog check only tests smog output at 15 and 25 mph. None of those solenoids do anything under those conditions. If your carb is missing the dieseling preventer solenoid, it won't make a bit of difference on the smog check. And the chances of the smog tech noticing that it is missing are about as close to zero as you can get. If you can rebuild a carb with the sight glasses and get it to run well, you'll pass smog without a problem. If you're missing a few controls, or some of them don't work properly, it won't matter a bit as long as you're blowing clean at 15 and 25.
I genuinely feel for you carb guys. Those junky Keihin carbs are all failing and you have to be very talented (and lucky, honestly) to get them rebuilt and running again. And the other options are not any easier. Either you fab something up or you re-do all your vacuum controls and try to sneak through smog. It's an ugly business no matter which way you go.
Hazwan
10-20-2011, 07:09 AM
Sounds like you found the root of the problem.
Since we are going to have more and more problems with carburator compatable fuels in the future....
I would just find a Weber 32/36 to put on the car. You will need something simple to service with parts readily available.
It doesn't have to be a Weber, but any aftermarket style carb that is still being sold as new would have parts available.
The accelerator pump diaphragm has steel in it and will be prone to growing rust in it that will eventually cause the diaphragm material to collapse. I think I would do the power valve hack mod to eliminate that extra part as well.
What is this hack that you're talking about?
And yeah I guess Weber would be an easier choice but I still would love to do the bike carbs :D
lostscotiaguy
10-20-2011, 01:23 PM
WOW Thanks for a great post Dr Snooz.... I'm starting to think that Guaranteed Carbs will be getting a call soon... I know if I had the time I could get an 82- up working with the right pieces, but I think I may have to do the inevitable and just "trust the professionals" to have done the proper adjustment. What I really can't believe is that I've been having to F*** around with this thing for years, and it's the only carb I've ever dealt with. Why did I have to pick the worst one to learn on? LOL
2oodoor
10-20-2011, 02:17 PM
hack, essentially deleteing the power valve which also is a diaphragm thing made with a bunch of dissimilar materials.
PV can really screw you up when youre jet tuning with a wideband anyway.
Hazwan
10-21-2011, 06:53 AM
So I've decided to take apart the carb just for lols
http://i.imgur.com/V3R0M.jpg
http://i.imgur.com/ttquE.jpg
Replaced all the screws with thinner/smaller ones for moar flow
http://i.imgur.com/YgMh1.jpg
The rare ass float level tool (Y)
http://i.imgur.com/WPaRz.jpg
So I found something interesting while I have them apart. Looks like the jet sizes are all messed up >< I have two extra/spare/parts carbs and the jets are the same except for mine. I've replaced them and hoping that would fix my lean problems!
I have yet to install the carb back into the car since I still need to get a new intake manifold gasket. It seems fine now but I'm not taking any chances!
And oh I had the whole carb soda blasted few months ago and too bad I can never get the whole thing back into the original silver/aluminum color anymore :(
2ndGenGuy
10-21-2011, 08:09 AM
I know you have the same carbs, but now I'm wondering... since you have JDM cars there, I'm betting you have both 1600 and 1800cc motors there. Maybe that's why the jet sizes were different. Probably bigger jetting for the 1800. That might be the way to go for your car, since you have a header and you've removed a lot of stuff on the carb.
2oodoor
10-21-2011, 09:07 AM
that float guage isn't rare at all, I thought he was talking about one you used without removing the top hat?
I would not have changed any screws out, there is not going to be any difference in flow geez are you kidding?
Besides that it is too risky for them to get loose and either fall into the motor or make the throttle jam wide open!!!
that is a huge float!
lostscotiaguy
10-21-2011, 12:52 PM
that float guage isn't rare at all, I thought he was talking about one you used without removing the top hat?
Yeah, I WAS talking about that crazy one that you hook up to the fuel lines and has a clear square shaped compartment to view the fuel level in and even some kind of "catch tray" for the fuel. Soichiro was a freakin genius but sometimes I wonder about Honda: "What were they thinking?" :rant:
lostscotiaguy
10-21-2011, 12:54 PM
Oh, and I could be wrong but I'd swear I have 2 different sized jets, mind you it's a CA car.
Hazwan
10-21-2011, 03:51 PM
I know you have the same carbs, but now I'm wondering... since you have JDM cars there, I'm betting you have both 1600 and 1800cc motors there. Maybe that's why the jet sizes were different. Probably bigger jetting for the 1800. That might be the way to go for your car, since you have a header and you've removed a lot of stuff on the carb.
No idea but that fixed the stumble for sure (Y)
that float guage isn't rare at all, I thought he was talking about one you used without removing the top hat?
I would not have changed any screws out, there is not going to be any difference in flow geez are you kidding?
Besides that it is too risky for them to get loose and either fall into the motor or make the throttle jam wide open!!!
that is a huge float!
Huge float indeed but I know what you mean with the screws LOL I figured why not since I had the shaft cut in half, at least on the secondary side. idk how to explain but look at the PICS up thar.
But yeah don't worry about them falling off or anything as I've got some thread lock applied to them (Y)
Yeah, I WAS talking about that crazy one that you hook up to the fuel lines and has a clear square shaped compartment to view the fuel level in and even some kind of "catch tray" for the fuel. Soichiro was a freakin genius but sometimes I wonder about Honda: "What were they thinking?" :rant:
Ah I saw a similar tool like mine in the manual so :Owned:
Oh and pretty carb is prettyyyy:
http://i.imgur.com/XkDUE.jpg
I've got the car running. Started on the first try :o Sounded way different now, way smoother and that stumble that I always get when its cold is now gone. And before anybody said anything about my missing choke, we never have any problems with carbed cars starting in the cold morning without even using the choke here in MDM land so thats not the issue here :D
But looks like I'm gonna need the intake/exhaust gasket after all. I couldn't wait so I had to reuse that just to see if she runs and omg she did :o Idles wayyyyy better now (Y) (Y)
Hazwan
10-22-2011, 03:36 AM
Okay I think I'm liking the look without that gay heat shield on now D: Tempted to polish the intake manifold now :D
But just curious, will a thermal wrap, wrapped (of course) on the exhaust header actually do something with lowering the bay temperature? I know the main purpose of it is to keep the heat so it would flow better and stuff but I hate how my under hood temp is being so hot now :(
Dr_Snooz
10-22-2011, 05:01 AM
That carb is a trip! It's so small! The California ones always have so much smog stuff bolted onto them that they are as big as a house. There really isn't much to them after all.
lostscotiaguy
10-23-2011, 01:38 PM
"The California ones always have so much smog stuff bolted onto them that they are as big as a house."
SO TRUE.... Check this out Hazwan, this is my carb...and NO, there ISN'T an octopus having sex with it...
http://img560.imageshack.us/img560/3615/dsc02591d.th.jpg (http://imageshack.us/photo/my-images/560/dsc02591d.jpg/)
Uploaded with ImageShack.us (http://imageshack.us)
Hazwan
10-23-2011, 03:52 PM
LOL that made my carb look a lot prettier haha stupid vac lines!
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