Bing Type 64 choke issue

[typ181r90]

Just went into the carbs and cleaned the jets, adjusted the float height (the fuel level was about 18mm instead of 24), and did a carb sync - everything else on the bike was in tip top shape, just wanted to do a little pm on the carbs (I didn't take the carbs off the bike for any of this). The bike is idling perfectly now and acceleration is the smoothest it's ever been. I don't know how it happened, but now the choke won't seem to work.

It used to be when the bike sat overnight or temps were below 70 I'd need to have the choke on for a little to get the bike started and if I left it on too long my RPMs would way up. Now I am able to get the bike started pretty well without the choke and if I try to apply the choke the bike will pretty much just die, even only opening the choke lever slightly. The choke cables are working properly and the choke appeared to be working fine until the minor job I did on the carbs. Is this how they are supposed to operate on these Bings or am I missing something really obvious? I thought maybe I had a rich condition and the choke was just killing the bike by making it way too rich, but I checked my plugs which are looking really good and the exhaust doesn't smell remotely rich.

am I missing something really dumb here? I can't seem to figure out what possibly could have gotten disturbed or why the bike would run otherwise flawless

 

[20774]

I can't speak for all bike's chokes, but on my /7 I've always needed (or used) full choke to start the bike when cold, even when it was 80 degrees outside. Usually after 30 seconds, I'll move the lever towards off but into the middle detent and then ride off slowly through the neighborhood. After about 0.5 miles, I turn the choke lever completely off.

It appears in your case that the old floats were adjustd to the lean side, thus requiring some choke to get started. But with the floats adjusted to have more fuel in the bowl, the need for choke is reduced.

But still, I would think that any given bike would need some choke to start in most situations after sitting overnight. But if the bike starts fine and you get decent gas mileage, I'd just go with it.

 

[boxerkuh]

No, I don't think that you are missing anything.... here is my rationale....

My 2 airheads start very differently... My 92 R100R is just like you... when the temps are above 70 degree's I don't need the choke at all... After a few days of sitting maybe for 30 seconds at best. The bike will not run with the choke on full on or even half way. My 86 R80RS on the other hands needs a choke everytime when she has been sitting more than 4 hours...

My 2 cents... although all the airhead engines are basically the same and the carburator is basically identical, they are still different and act differently... just like 2 children with the same parents...

The way the choke was explained to me years ago is that our bing carbs are basically 2 carbs into one... the main carb that you run the bike with 99% of the time and the 1% when you use the choke. It allows more fuel to run the bike richer until warmed up...The choke is only used at idle, as soon as you use the throttle while riding take the choke off.... if you do that the plugs will run right, you can tell if you are running with the choke on too long by checking the plugs. How do your plugs look? Probably fine.... my food for thought..

 

[typ181r90]

My practice was exactly like yours Kurt, full choke to start and within 30 seconds I could back off and by the time I was at the end of the block it was fully off. Boxerkuh it's good to hear the discrepancies between two mostly identical bikes... My plugs look perfect and that's what was causing all the head scratching. I literally couldn't take my mind off this all night at work playing out different possibilities of what could have happened and I'm stumped.

I work night shifts and it's supposed to hit the low 40s tonight in NJ, I'll see how the bike starts after that and then I guess I'll find out whether or not the choke will work and if I have to start digging deeper.

thanks for the replies, I'll post an update tomorrow after the cold weather

 

[amiles]

My guess is that your prior incorrect float level required adjustments out of the normal range (rich) for running which now with proper float height will not function properly without re-adjustment.
My suggestion would be to re-adjust your idle mixture jets using the procedure in the Bing book.

Initial idle mixture screw settings are from .5 to 1.5 turns out from contact depending on the bike.. Count the turns as you run the needle in for reference. expect to adjust the idle speed as well.

 

[typ181r90]

My guess is that your prior incorrect float level required adjustments out of the normal range (rich) for running which now with proper float height will not function properly without re-adjustment.
My suggestion would be to re-adjust your idle mixture jets using the procedure in the Bing book.

Initial idle mixture screw settings are from .5 to 1.5 turns out from contact depending on the bike.. Count the turns as you run the needle in for reference. expect to adjust the idle speed as well.

That was the first place I looked and the idle mixture is normal. Just a hair above a full turn on the left side and nearly a full turn on the right. When I synced the carbs I closed in in the mixture screws and then opened them slowly to listen for the sweet sport to establish a baseline mixture and counting the turns all the while. I then proceeded to do a proper dynamic sync with the shorting out method using snowbum's steps.

 

[typ181r90]

And I do have the Bing manual

 

[guenner]

How did you clean the jets? Compressed air with jets still installed or, did you remove the jets first?

/Guenther

 

[typ181r90]

UPDATE

it's 0030 at work at the outside temp is 50F. Bike is nice and cold from my 2130 ride in and I figure I'd try the choke now that the temp is cool. No go on the choke, still died. Tried starting with no choke, no good either. Battery is slowly dying as I try different things around when I finally decide to reset the float level. Instead of using the 24mm, I decided to use the visual check of making sure the float is parallel and adjusted both floats. Float level is now a bit lower (I'll get a measurement when I get home in the morning and update) than 24mm. Tried to start the bike again and the choke worked perfectly, got the bike running, backed off the choke like normal and everything is good (though I have slight deceleration popping in low gear, may fix that with another sync when I get home)...

I'm going to leave the floats adjusted in this manner, but here is something of interest. The floats I'm using now are the black colored Bing ethanol resistant ones in the old style, not the other independent ones. I'm wondering if this has anything to contribute and that maybe the float level needs to be different using these new floats? Maybe my float bowls aren't correct for the carbs or with the new floats?

I really don't know, but now the bike is running again and I'll fine tune it when I get home and update again

 

[20774]

I'm wondering if this has anything to contribute and that maybe the float level needs to be different using these new floats? Maybe my float bowls aren't correct for the carbs or with the new floats?

Seems to me what matters is the float level for the jet stack so that the carb can get the right amount of fuel for normal operations. So, I think it doesn't matter what float you use, just that you get the fuel to the right level.

But the starting circuit is different than the normal operation circuit, isn't it? I wonder how much the fuel level affects that...it seems to in your case. There is a stand tube off the right in the float bowl and a small screen at the bottom of that. Maybe this should be investigated to be sure it is all clear.

 

[typ181r90]

Seems to me what matters is the float level for the jet stack so that the carb can get the right amount of fuel for normal operations. So, I think it doesn't matter what float you use, just that you get the fuel to the right level.

But the starting circuit is different than the normal operation circuit, isn't it? I wonder how much the fuel level affects that...it seems to in your case. There is a stand tube off the right in the float bowl and a small screen at the bottom of that. Maybe this should be investigated to be sure it is all clear.

Right, the idle circuit is separate from the normal operating circuit, but I really don't know how the level would affect it, I guess in this case it would over richen it to the point that using the choke would be impossibly rich?...

I used the eyeball method earlier this morning to set the floats to parallel at the point where they stop/start the fuel flow. It was 42F when I got out of work an hour ago and I used the choke to start the bike and it worked as it should. I took a 20 mile extended ride home from work and idle was looking good, a little high at about 1100, but not too much different from the 1000 I set it at using the higher float level - especially considering I didn't touch the mixture screws or idle speed screw after re-adjusting the float level this morning.

When I took the float bowls off they both measured 20mm of fuel. Yes it's short of the 24mm it's supposed to be, but the floats are parallel to the bottom of the carb when they stop/start the fuel flow

Here's a picture of the bowl with the 20mm fuel height, and yes I did measure from the low point in the center of the bowl.

I can't figure this one out, I'm thinking I'll just leave it as is because I definitely need a functioning choke, but I keep returning to the idea about the new Bing ethanol resistant floats. I took the old ones (standard white ones) and compared them to the new black hinged ones and they are slightly shorter in length with a tapered bottom toward the front. The Bing black ones do not have this taper and seem to be slightly longer. Maybe after I wake up from my daytime sleep I'll go back out to the garage and take the black ones off the bike and do a side by side comparison picture.

 

[typ181r90]

How did you clean the jets? Compressed air with jets still installed or, did you remove the jets first?

/Guenther

G??nther, I removed the jets to clean them

There is a stand tube off the right in the float bowl and a small screen at the bottom of that. Maybe this should be investigated to be sure it is all clear.

Kurt, if mine had screens they don't seem to be there anymore and the passage was clear on both

 

[20774]

I wonder if the problem is your cold-start system or the choke itself. I realize these bikes are all snowflakes, but it just seems that setting the fuel level low so that the choke works is somehow compensating for something wrong somewhere else. In the bigger picture, a lower fuel level in the bowl is going to make the bike run leaner because of the increased difficulty of pulling the fuel up the jet stack. It would surely be a problem if you ran at higher RPMs or say 3/4 throttle a lot...I suspect you'd stare the engine for fuel if run that way for a long stretch.

 

[donbmw]

Check your fuel bowls. The choke currect has a orffice that could be stopped up. It is in the bowl. Some models this jet can be removed. I had this on a 75 R90/6 I bought in the summer then when cool weather came I was finding it hard to start and running rough until it warmed up. That when I found the jet in the bowl for the check was stopped up. You may need to go back and removed the carbs and clean everything and use a carb soak cleaner.

Don

 

[typ181r90]

I wonder if the problem is your cold-start system or the choke itself. I realize these bikes are all snowflakes, but it just seems that setting the fuel level low so that the choke works is somehow compensating for something wrong somewhere else. In the bigger picture, a lower fuel level in the bowl is going to make the bike run leaner because of the increased difficulty of pulling the fuel up the jet stack. It would surely be a problem if you ran at higher RPMs or say 3/4 throttle a lot...I suspect you'd stare the engine for fuel if run that way for a long stretch.

Well, the floats are set correctly using one method (parallel set) and low using the other method (fuel level). I do run at highway speeds most of the time and I just ran at a consistent 4500-5000rpm range on a 10 mile ride a couple hours ago. It didn't feel too lean at those rpms and I was able to get it to 105 comfortably for about a 1/2 a mile just to see if it felt bad at the higher rpm range. I just pulled the spark plugs which look pretty good but maybe a tad lean, slight tan deposits on the insulator and a good looking electrode, but not as much tan as I'd like to see. I think I'm going to have to try and raise the fuel level and play around with the choke to see how I can get it with a functioning choke until this winter when I'll be doing the neutral switch and some other misc. stuff and the bike will be oos.

Check your fuel bowls. The choke currect has a orffice that could be stopped up. It is in the bowl. Some models this jet can be removed. I had this on a 75 R90/6 I bought in the summer then when cool weather came I was finding it hard to start and running rough until it warmed up. That when I found the jet in the bowl for the check was stopped up. You may need to go back and removed the carbs and clean everything and use a carb soak cleaner.

Can you explain this a little bit better, I don't see anything in the bowl like that and I'd like to investigate this further

 

[typ181r90]

alright, problem appears to be fixed...

this time when I adjusted the fuel level in the bowl, I turned both petcocks on instead of only the one I was working on and raised the float level and checked the choke in steps. Now I've got the 24mm fuel height and a functioning choke, took the bike out for a 25 mile ride and everything is well. Going to check the plugs after the heads cool down, but I expect them to look better than the had earlier

hopefully this is it, I guess the fuel crossover tube was what was making all the difference in this case. I'm working overnight again and the temps are going to be in the 40s, we'll see if the choke is still working in the morning

 

[donbmw]

When looking at the picture of you float bowl. The small open by you index finger is the fuel supply for the choke circuit. There is a small jet that can get stopped up also check the hole at the bottom of this area in the main fuel bowl. Like I said this jet may come out but this is not on all of the Bing Carbs. My R90 you could not remove this jet so I had to find a stiff piece of wire to be able to unstop it. I don't see how the float level is going to make it start easy. The float level is either not high enough causing you to run out of gas under power or it's to high and leaking out the overflow. I don't think you would set the float level so low that the float level would make it hard to start.

Don

Right, the idle circuit is separate from the normal operating circuit, but I really don't know how the level would affect it, I guess in this case it would over richen it to the point that using the choke would be impossibly rich?...

I used the eyeball method earlier this morning to set the floats to parallel at the point where they stop/start the fuel flow. It was 42F when I got out of work an hour ago and I used the choke to start the bike and it worked as it should. I took a 20 mile extended ride home from work and idle was looking good, a little high at about 1100, but not too much different from the 1000 I set it at using the higher float level - especially considering I didn't touch the mixture screws or idle speed screw after re-adjusting the float level this morning.

When I took the float bowls off they both measured 20mm of fuel. Yes it's short of the 24mm it's supposed to be, but the floats are parallel to the bottom of the carb when they stop/start the fuel flow

Here's a picture of the bowl with the 20mm fuel height, and yes I did measure from the low point in the center of the bowl.

I can't figure this one out, I'm thinking I'll just leave it as is because I definitely need a functioning choke, but I keep returning to the idea about the new Bing ethanol resistant floats. I took the old ones (standard white ones) and compared them to the new black hinged ones and they are slightly shorter in length with a tapered bottom toward the front. The Bing black ones do not have this taper and seem to be slightly longer. Maybe after I wake up from my daytime sleep I'll go back out to the garage and take the black ones off the bike and do a side by side comparison picture.

 

[m_stock10506]

"Can you explain this a little bit better, I don't see anything in the bowl like that and I'd like to investigate this further "

Looking at your picture of the carb bowl; the well that's all the way at the left corner is the starting circuit. There is a hole at the bottom of this well that pulls gas into the well from the main float bowl. This orifice has to be clear for the choke to operate properly.

 

[PGlaves]

If you reverse the float bowls carb to carb the choke (enrichener) circuit won't work.

If you reverse the enricheners carb to carb the enricheners won't work.

 

[HP1BMW]

If you reverse the float bowls carb to carb the choke (enrichener) circuit won't work.

If you reverse the enricheners carb to carb the enricheners won't work.

alright, problem appears to be fixed...

this time when I adjusted the fuel level in the bowl, I turned both petcocks on instead of only the one I was working on and raised the float level and checked the choke in steps. Now I've got the 24mm fuel height and a functioning choke, took the bike out for a 25 mile ride and everything is well. Going to check the plugs after the heads cool down, but I expect them to look better than the had earlier

hopefully this is it, I guess the fuel crossover tube was what was making all the difference in this case. I'm working overnight again and the temps are going to be in the 40s, we'll see if the choke is still working in the morning

Did you remove the choke assemblies when you cleaned the carbs? If so it is quite possible that you put them back on in the wrong position. Trere is a small dimple on the shaft that controls the choke, that dimple should be towards the extension that comes off the square choke body. If you have the in backwards the choke will not work properly.

Jim