MAJOR CBX ENGINE PROBLEMS

pswilcox@earthlink.net · Mon Apr 21, 2003 3:28 am

Bad CBX Problems...

I just finsihed restoring a 1980 CBX that had been sitting for the past 11 years.

Bad news is, it runs like CRAP! Specifically....

-- It only runs with the choke full on -- even when hot (and even though the carbs have been meticulously rebuilt and adjusted)

-- It has a horrible rattling noise deep in engine cases (primary chain?)

-- There's a LOT of valve train clatter (even though valves have all been adjusted, as have the cam chains)

-- Most (if not all) the carbs overflow out of their drain tubes for no apparent reason.

Any reasonable person would say, "Gotta take the engine out, tear it all the way down and find the problems. No, that would be too rational. I'm already thinking of going to one of two extremes: (1) find another engine, clean it up and put it in or (2) take the whole thing apart, put all those beautifully restored parts into individual baggies and sell 'em on eBay one at a time.

Anyone have some advice to share? Maybe a spare engine??

Thanks,

Paul

Guest · Post by **Guest** » Mon Apr 21, 2003 3:34 am

Souns like your carbs still have major problems......which will contribute to your primary chain/clutch noises.

New Oldham couplings will more than likely resolve your top end noises.

Good Luck

Ed

Don · Post by **Don** » Mon Apr 21, 2003 9:48 am

I agree.

No matter how "meticulous" you were, it's pretty obvious you still have carb problems.

I'd be interested in getting an accurate reading on the oil pressure - Low could mean the primary chain (and valves) would be noisy.

If you attempted to adjust the cam chains the "Honda way" with it running (especially, running poorly) then they could still be the source for much of your internal noise - Do the valve cover off, manual adjustment, and perhaps much of that will go away.

Don

RIPPER · Post by **RIPPER** » Mon Apr 21, 2003 9:49 am

Did you put a wire through the pilot jets?Every idle problem I've heard about (no matter how well the carbs were clean)come back to pilot jets being clogged.If the carbs over flow doesn't that mean the floats are not set correctly?Does any of the noises go away when you pull in the clutch?basket can be noisy.

xneric · Post by **xneric** » Mon Apr 21, 2003 1:24 pm

You weren't meticulous enough with your carb rebuild. The pilot jets are the smallest, and you have to either visually determine they are clear or run something through them. Be careful not to enlarge them with whatever you use. Either you got a lot of dirt into the needle and seats from the tank or you did something wrong there too.
CBX's can make a lot of "bad" noises if all cylinders aren't doing their equal share. With your carbs so badly out, it doesn't stand a chance. Tilt the engine, and pull the carbs. Make sure you can blow air or spray through each hole of the carb. Spend the time to find out where each passage goes so you can verify this. Also find out why your needles are leaking, and make sure all float levels are within specs. Get those carbs straightened out, and then syncronize them....this is a very important step. Then worry about those engine noises if you can still hear them. Good luck, Eric

sr71cbx · Post by **sr71cbx** » Mon Apr 21, 2003 7:57 pm

Land_Shark · Post by **Land_Shark** » Tue Apr 22, 2003 12:39 am

And just to be safe make sure you put the cams back in properly and not 180 degrees out as per the official service bulletin. Depends how loud that valve noise really is

Ric · Post by **Ric** » Tue Apr 22, 2003 11:06 pm

Everything everyone else said. Plus, get the carbs right first. Check the fuel valves for proper operation. And make sure to check the carbs on the bench before reinstalling them. With the carbs all toghether and banked up, fill them up to see if they leak or overflow. You can use a long piece of clear tubing on the fuel bowl drain valves to see exactly where the fuel level is in the bowls. Make sure they all come up to the same point. With the floats set correctly the fuel level should not touch the bowl gaskets. Check this out with the carbs tilted as they are when mounted on the bike.

Also, did you say you balanced the carbs ?

You know, if you didn't feel like doing all this again, you could take it to a good CBX mechanic who might just get it perfect for a few hundred.

CRAZY DAVE · Post by **CRAZY DAVE** » Thu Apr 24, 2003 4:58 pm

Having done the carbs on both my new 79 (not run since 1985) and my 80 (not run since 99 but had stabilizer in it ) in the past week,I found the easiest way to unclog the pilot ( idle ) circuit. Lay the carb assembly upside down on a small TV tray in front of your favorite patio chair. Cut a 12 oz. soda can in half and fill the bottom of it with a mixture of 3 parts gas and 1 part Yamaha carb cleaner. Take an old Windex sprayer and cut about a 3 inch section of the tube off to use as a cheap eye dropper. Fill the idle circuit to the top with the mixture. Take a 6 inch of cheap thin single strand copper speaker wire that is about the same size as the jet and file down the end to a taper. After soaking the jets for about 2 or 3 beers gently push the wire all the way to the bottom of the jet. If you have enough patience when it finally breaks thru the clog you can fill the jet housing up with your mixture and will drain into the venturi by the throttle blade like a newly unplugged john. You can occasionally spray some carb cleaner into the jet to help plunge it. Any ?, just let me know. PS. do not leave eye dropper in mixture long it will melt !! Crazy Dave

Ric · Post by **Ric** » Thu Apr 24, 2003 6:20 pm

Guitar strings are good too. They're pretty stiff when cut short and they come in all sizes. They're cheap too, or a local guitar shop will give you a bunch they've cut off.

sr71cbx · Post by **sr71cbx** » Thu Apr 24, 2003 8:22 pm

Terry · Post by **Terry** » Thu Apr 24, 2003 9:38 pm

Hey don't rub it in Mark. :) I kinda like six barrels.

Has anyone figured out the cfm rating of the six carb set up? How about your one barrel Mark? You know what I mean, a common four barrel v-8 carb could have 650 or 750 cubic feet per minute fuel (passage) capability. Jetting would cause an increase too I suppose. I wonder how many cfms a stock set up has?

Don · Post by **Don** » Thu Apr 24, 2003 10:07 pm

I don't think the CFM's translater over into "V-8 terms" as your car's intake manifold is pulling a consistant amount of air through the carb at any steady RPM - For our carbs, nothing flows through them 3/4ths of the time, as each carb just flows for the 90 degree intake stroke, and not a consistant amount of flow even then - Less at the beginning of the piston down stroke, maxxing out part way down, and then little again for the last few degrees.

Pretty hard to compare "air flow" to your V-8 Chevy ;)

Don

sr71cbx · Post by **sr71cbx** » Thu Apr 24, 2003 11:00 pm

CRAZY DAVE · Post by **CRAZY DAVE** » Fri Apr 25, 2003 10:00 am

Yes, 1 carb is much easier but so is riding a Hondamatic !!! Crazy Dave

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