A question for carb tuners

Inglbird · 06-21-2008, 3:51 PM

Hi guys, I'm the new guy here. Great site with lots of info. I just picked up a 97 a few days ago that the previous owner was told had exhaust work done to it. I'm not convinced cause it has the stock cans on it, even tho one has a BPRR sticker on it. Anyway, it is a little laggy when I snap the throttle from idle, and seems to have a more than average lull in power at around 5k rpm's or so, but still totally wakes up at 6500-7000. I haven't done a plug check, but because it runs so well at high rpm's, I'm thinking maybe just needle hight may fix this. And maybe a bit of air screw tweeking. (Does the Bird have air screws or fuel screws? I haven't looked yet.)
What are some of your more professional opinions?

Thanks

bullet · 06-21-2008, 6:08 PM

..well since you own a 97 model your exhausts do not have any catalysts of similar emission stuff...so the "exhaust done" could be anything from a possible weldind ...or matching a carb needle kit with your current exhaust setup....inspect the possible modifications that might have done by the previous owner so that you can have a starting point for future alterations...

Inglbird · 06-21-2008, 8:32 PM

Quote:

Originally Posted by bullet

..well since you own a 97 model your exhausts do not have any catalysts of similar emission stuff...so the "exhaust done" could be anything from a possible weldind ...or matching a carb needle kit with your current exhaust setup....inspect the possible modifications that might have done by the previous owner so that you can have a starting point for future alterations...

Well, that's kinda what I mean. I don't see anything that says it was modded. But maybe if I had a stock muffler to do a side by side I might see something. It all looks and sounds stock to me. If there was work done, it is extremely seamless. Anybody have any pictures from the back of the rear opening on their stock cans for me to compare? I have read a lot that a stage 1 jet kit will take care of the stock power hole in the mid rpm range, but again, I don't know how a stock machine should feel. It just feels like it's not tuned right and I would hate to think that a factory machine would run like this from the beginning. Like I say, it's not really bad, but could be more my ocd tendencies than anything I suppose.
I do know that I have not yet ridden a bike that has the low end torque and power of my old Suzuki GS's. I guess I could just still be expecting that too. I would have to say that my old GS would have this Bird out of the hole, but the Bird would definitely walk away when it hit it's curve.

jsfrv6 · 06-21-2008, 8:48 PM

To the forum...

Post some pics of your cans so we can see what you got...

Inglbird · 06-23-2008, 11:05 PM

Ok, sorry I don't have pics of the cans yet, but I'm pretty sure they are original inside and out. But I have noticed that when I hit it hard it kinda lags until 6000 rpm's or so. But it seems that if I don't peg the throttle completely it picks up alot better. Since there is no popping I'm kinda thinking it's running a bit rich. What do you think? I also assume this has the primer/enrichner type choke. Anybody have issues with these sticking partially at all?

Inglbird · 06-26-2008, 8:04 PM

Well, I took the carbs apart today and didn't find anything. I checked the pilots and they were clear, no crud in the bowls or anything like that. Changed the plugs, the old ones looked good. Just about the right color, possibly a little darker than they should be, but but still a golden brown. The jets are 140 on 1 and 4, and 142 on 2 and three. That's stock, right? Jeeze, I don't have the money to have these tuned and what not. Does nobody have any ideas?

jsfrv6 · 06-26-2008, 9:14 PM

Make sure you check the diaphrams for splits / holes. also check slides for smoothness. If you literally "took you carbs apart" make sure you replace the o-rings on the fuel tubes between the carbs and the ones on the vacuum tubes between the carbs as well. Ask me how I know that.

Inglbird · 06-26-2008, 9:36 PM

Quote:

Originally Posted by jsfrv6

Make sure you check the diaphrams for splits / holes. also check slides for smoothness. If you literally "took you carbs apart" make sure you replace the o-rings on the fuel tubes between the carbs and the ones on the vacuum tubes between the carbs as well. Ask me how I know that.

Ah, the diaphragms, that's a good call. I will check those better. I didn't tear them down completely, so the o rings should still be good. Although I didn't know there was a vacuum line between them.
God I'm sick of taking that thing apart..... about ready to take out a second mortgage to just have somebody do it.

Thanks for the input

jsfrv6 · 06-26-2008, 9:39 PM

Quote:

Originally Posted by Inglbird

Ah, the diaphragms, that's a good call. I will check those better. I didn't tear them down completely, so the o rings should still be good. Although I didn't know there was a vacuum line between them.
God I'm sick of taking that thing apart..... about ready to take out a second mortgage to just have somebody do it.

Thanks for the input

Hang in there... You'll get it. I can take mine apart in nothin flat with my eyes closed.

You are becomeing one with the bike grasshopper

Inglbird · 06-26-2008, 10:10 PM

But I don't wanna work on it anymore. It's supposed to be perfect damnit.

Inglbird · 06-26-2008, 11:38 PM

Ok, the diaphragms seem good, I held them up to the light and didn't see anything. The slides all felt good and felt the same. I think it's running worse too. Or I'm becoming more attuned to it. A lopey idle and a deffinate hesitaion when you goose it from idle with a not so snappy rev up. And some deffinate lag and a little sputtering when accelerating. It's not so bad if I roll up on the throttle.

The bright side, I shaved 3 more minutes off my teardown time.

jsfrv6 · 06-27-2008, 10:37 PM

If you don't have a repair manual,
Download this
http://www.cbrxx.com/attachments/hon...ice_manual.pdf

These carbs seem simple at first but they are pretty complex. This manual does a good job on the details. Better than my Haynes Manual. For example, the Idle mixture (pilot) screws have a spring, washer and an O-ring. The Haynes manual talks about these parts but doesn't have an illustration so it's easy to miss. The Honda manual shows these parts. In general this manual has much better illustrations.

Did you clean the low speed jet? If any of these are plugged, the bike will not idle right and you will have a dead miss on that cyl until you start to get into the main circuit. If the Idle mixture (pilot) screw is not adjusted properly or the circuit is plugged, it will not idle properly. If the O-ring and or washer is missing from the Idle mixture (pilot) screw, It will not idle right.

Get this manual, study the information and you should be able to beat this. I went throught the same things when I first got mine. Now it starts every time, idles great and runs like new.

Inglbird · 06-28-2008, 2:08 PM

Thanks Jsfrv6, I have the carbs off and apart again. All my fuel screws were pretty close to the same at 2 3/4 turns. Everything looks really clean. I'm taking a break right now. Man, Oregon is having another heat wave. 11:00 and already 88. Jeeze. Last week it was in the lower 60's.

Anyway, while I have them apart, does anybody have any suggestions to try, or something I may forget to check? I would be very much obliged. Wish me luck guys, I really need to be riding right now.
Although they all look good, is there much chance that the choke/enrichners could be missbehaving?

Thanks again,
Erik

Inglbird · 06-28-2008, 2:20 PM

What's the air cuttoff valve? This sounds like it could be a culprit to cause these symptoms doesn't it? And it looks like mine may have one. Hmm...

jsfrv6 · 06-28-2008, 4:17 PM

Looks like the air cut off valve is only on the california models. Check your vin#.
If you have them apart, it would be best to get them soaked in some carb cleaner but at least get some spray type carb cleaner, Berryman Chemtool is the best, and give every orfice a good shot. Then follow up with compressed air.

Inglbird · 06-28-2008, 6:54 PM

Well, I got it running pretty good now, and although better, it still isn't idling smoothly, but they may need sync'ing too, I don't know. I cheated in my opinion, I just cranked the mix screws out some more. The hesitation is gone, and it accelerates smoothly now. I looked and checked for vacuum leaks. Didn't find anything. So they are all about 3 1/2 turns out now. I don't want to go any further cause I don't want em to fall out. It has to be a restriction in fuel or a vacuum leak, right?

jsfrv6 · 06-28-2008, 8:09 PM

Now that it's runnig decent put some carb cleaner in the gas to clear out an left over varnish. Seafoam cleaner seems to work well but make sure you use the right amount...

Good work grasshopper

now go put some miles on it

Inglbird · 06-28-2008, 8:15 PM

Thanks, I would love to go try it out, but it's 103 here now and just too friggin hot. This is Oregon for crying out loud. It was in the 60's last week!

I'm not done with this stupid thing yet, there is still something up. I put treatment in this tank when I filled it up. Only have about 75 or so with it so far. I hope it clears it up. I'm suprised it's lean, I really thought it was running rich....

Thanks for the help.

TigreST · 06-28-2008, 9:28 PM

What I'm about to type is not specifically Blackbird related, but it may also apply. In my dealings with the older Honda CB-F bikes time and time again it becomes somewhat apparent that if you go through numerous carb removal and install routines you run the risk of putting cracks in the intake manifold rubber boots. More so with older parts that have seen years of heat cycles while in use. The flex they have when new will have long since left the building with Elvis one might say. In Honda speak these are called:
INSULATOR, CARB (with a Honda part number of) 16211-MAT-000 (for the 97 1100xx).
They run to about $28.00 each state side and over $40.00 in Canada (at least I think that's what I paid?). Anyway, these things crack and cause air leaks and a lean condition...at least on my old 1983 CB-F's. I have a Ti Force pipe to install on my Bird along with a Factory Pro Jet kit to dial the carbs in with. New "Carb Isolators" sit in wait also. I do this (within reason) every time older boots are involved with a carb install. It's just not worth the aggravation to not have them serviceable after the carbs are installed.
One way to check for leaks at the carb isolators is to start the engine and spray WD-40 (or something similar) in the area of the boots and head/carb interface. If there is a leak the WD gets sucked into the intakes and the engine idle characteristic's will change.

Tony

JayO · 07-31-2008, 1:45 AM

How's it going all? I was reading some of the issues and symptoms that Inglbird was having and they sound familiar. I have a question though, can you sync carbs without guages?? From what I read and have read, it seems like you can do this by ear or am I way wrong?? I know it won't be "perfect," but will a few twists of some screws eliminate some problems?? I mean my Bird is running somewhat hot, although it is and has been in the high 90s and riding around town, but dammit...I'm getting like 100mis a TANK!

About how much is it to carbs tuned or sync'd anyways?