OVERFLOW:Double check on float level

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porschekz
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OVERFLOW:Double check on float level

Post by porschekz »

Hi gents,
I just refurbished the carbs if my 80 CBX using Mike Nixon instruction book and Randakk' s parts plus a full set of new needles, but somenthing is wrong in float level settings (even I used the right caliper tool) since the run is TOO RICH. The engine is starting very well but it smells so rich at idle and when i puss the trhottle the exhaust gases look really black.. It looks that the float level is so high. I tried twiced with same bad results.
The engine has been refurbished (19kmiles on the odometer) with new rings, valve seals and stock foam air filter. The main jet are also stock 110 size and the pilot screw is adjusted at 1-1/4 turns
Are there any way to check whether the float level is right using an external U tube connected to the carburator drain? I ' m using this way to adjust the flow level in my KZ 1000 carbs and it works perfectly (smooth ride and an excellent fuel average of 5.8 liters/100km, around 40miles/galon)
In case of the CBX if I' ve made a bench carb support simulating the right angle of the carbs on the engine head (~22°). I would like to use a double check way to adjust the float level before to reinstall the carbs on the bike (float level tool an external level hight in an external U tube). What could be the right hight of the fuel level on the external U tube with the carbs simulating the right shaped angle (22°)?

Cheers from Spain

daves79x
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Re: OVERFLOW:Double check on float level

Post by daves79x »

Level should be about the center of the large mounting screws on the front of the rack. However, I 'm guessing you have another problem. Check choke operation and main jet true size. Many are drilled out.

Dave

porschekz
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Re: OVERFLOW:Double check on float level

Post by porschekz »

Hi Dave,
Thanks for your quick replay. If I understood well the fuel level height should be as is remarked in the attached picture isn't it?.Please advise.
In relation to the choke system I ve already checked and it is working fine. The main jet (110) size look stock size, since the bike was very well preserved. Ant way are there any way to check its size? What it is the nominal diameter size?

One more questions related to how adjust the carbs each other with the vacumeters. Please check the second picture with my carb set top view (please remember that is a model CBX 80 model A ). It seems that the adjusting screws between the carbs 1 and 2, the screw beside the carb 3 and the screw between the carbs 5 and 6 are very accesibles for the adjusting tool. However the adjusting screws between the carb 2 and 3 as well as between the carb 4 and 5 are not accesible from the top of the carb rack. Then how can I adjust these last ones? Should be necessary check the vacuum difference at idle, stop the engine, readjust these innaccesible screws and measure again till the vaccum pressure readout are on the right margin?

Other question is how I can connect the vacumeter with the carb 3 if this output is used with the vacuum line connecting the fuel valve. I guess that I need to move the vaccum line to other carb when I'm testing the carb 3 isn't it?.

Thanks in advance for your kindly support. :text-thankyouyellow: :text-thankyouyellow:

Juan
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daves79x
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Re: OVERFLOW:Double check on float level

Post by daves79x »

Your picture has the carbs tilted backwards. They tilt toward the connecting rubbers and the level should be in the middle of the large Phillips head mounting screws, when tilted approximately as they are on the bike. I'll get to you other questions tomorrow.

Dave

porschekz
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Re: OVERFLOW:Double check on float level

Post by porschekz »

Dave,
Uppp. Sorry for the big mistake on taken the picture.
Thanks, Juan

daves79x
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Re: OVERFLOW:Double check on float level

Post by daves79x »

You need a set of wire gauges to check jet size. Drills work also. Also make sure you air cut-off diaphragm is not torn and that whole system is clear. Also make sure there are no intake or exhaust restrictions. If all that fails, get a set of 105 mains and try them (stock size for the Pro-Link). Your carbs are VB62 - correct?

Most guys have a set of 4 or 6 vacuum gauges and appropriate stems to screw into the vacuum ports on the carbs. Yes, you need to either by-pass the whole vacuum valve to do this, or fashion a way to hold the diaphragm open. Separate vacuum source works, like a MityVac brake bleeder.

The 2/3 and 4/5 adjusters are accessed from the upper back of the carbs right in the scallops of the top rear mounting pieces. You need 2 separate tools to get to all of them if they are on the bike. A short, stubby one is needed between 5 and 6 due to frame rail interference. Just bench sync them as close as you can get them and they'll likely be fine.

Dave

porschekz
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Re: OVERFLOW:Double check on float level

Post by porschekz »

Dave,
Thansk again for the valuable info you gave me.I would follow these by sure.
In relation to replace the main stock jets (110) by 105 jet size. How the performances would be affected?. Do you means that 110 are so large to get a proper adjustment and a good mileage?.
Juan

daves79x
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Re: OVERFLOW:Double check on float level

Post by daves79x »

If nothing else pans out, changing main jets is something to try. But if you can positively gauge that the 110 jets in there now are OEM Keihin 110s, and the carbs are indeed VB62, then it's not that.

Dave

porschekz
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Re: OVERFLOW:Double check on float level

Post by porschekz »

Dave,
Thanks again for your valuable info.
However I've one more question. I' m rechecking all adjusting carbs measurements using the Mike's carb refurbish manual as well as the Official Honda manual for the Z model. Both manuals are similar except the adjustment of the pilot screw. While the Mike's manual recommends to fix the idle mixture screw to 2 1/2 turns, the Honda Manual recommends 1 1/4 turns. I used this 1 1/4 adjustment in my VB 62 carbs of my 80 Model A bike. What is the right preliminar setting prior to the final pilot screw adjustment?
Thanks for your kindly support.
Juan

daves79x
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Re: OVERFLOW:Double check on float level

Post by daves79x »

I set them at 2 turns out usually, then let them there. Honda's setting is pretty lean.

Dave

porschekz
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Re: OVERFLOW:Double check on float level

Post by porschekz »

Hi Dave
I'm still working in my 1980 carbs since they are toooo reach. I've measured 7/8% CO even with the pilot full closed. Therefore something is woeking wrong.

Firstable I build a carb test bench to measure the right float level (see picture). The test bench reproduce the tilt of 22° of the engine as well as the correction of the refetence level between central and external carbs.

Using this bench please see how it looks the float level of the 4/6 carbs aligned with the philips screw you mentioned to me. It seems that there are and the same LEVEL, but please confirm me whether this adjustment is OK. However wven with this adjustment the engine was still so reach.

Therefore I was nvestigating in another root source. Finally I founded that the slide guide are broken and bended. Therefore they are not closing well and the air is passing trough this way and the slide are open. May be this is root problem. I'm purchasing a full set of new slides guide. I will inform you if this is finally the problem.

Please confirm me whegher the float level i fixed in my tcarb test bench is the right heigt.

Cheers, JUAN
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daves79x
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Re: OVERFLOW:Double check on float level

Post by daves79x »

The level looks pretty close, maybe just a bit high. But shouldn't be causing your problem. Check to be absolutely sure your air cut-off circuit is clear in all carbs and make sure the main jet air bleeds are open. They are the little brass tubes projecting upward under your cracked slide guides.

Also looked back through the thread and see no mention of the #35 pressed-in jets. Did you remove these to clean them? If so, did you confirm that they were not drilled out by a previous owner? This is very common and will cause your problem. Also check to be sure your metering (slide) needles are marked 55A. Those are the stock Honda '80-'82 needles.

Dave

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