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Discussion Starter #1
bought this 79 custom that had been sitting for 3 years. cleaned the carbs and jets and found a broken off mixture screw (screwed in all the way with tip still in place). when i opemed the petcock the carbs started to overflow badly. reopemed thr carbs and recleaned everything

reassembled the carbs and set the non broken mixture screw at 2 turns out.

I think i am running super rich because...

bike will not start without my hand applying throttle.

bike will die if choke is applied.

smell of burnt gas from exhaust.

bike will run good when fuel line is empty and carbs are starved of fuel.

bike drinks way too much way too fast.


air filter is clean. no air leaks around carbs or engine. i would think that with the broken tip of the LH mixture screw all the way i would be running lean ?!.

bike has 36 000km i will swap the spark plugs reset the cam chain tensionner and adjust the valves. i dont know what to try now.
 

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To clarify, you still have the broken tip stuck in once carb? That should make that carb lean. Were the two jets in the bowl installed in the correct hole? Bigger jet in brass emulsion tube, smaller jet in aluminum hole.
 

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Discussion Starter #3
i have one jet written 112 and another one that the marking is unreadable (im guessing 78. the 112 is in the casted body of the carb and the 78 in the emulsion tube. amd yes the broken tip is still in but i am running supper rich.
 

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Discussion Starter #6
i just opemed my carbs and the 78 is in the aluminum body of the carb and 112 is in the brass tube. i am out of ideas
 

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Can you verify both choke plates are open fully when the choke knob is pushed in? Check fuel level with a clear tube from the bowl drain and lifted beside the carb, fuel level will show in tube, should be near the bowl joint line (just a smidge below the joint). Too high a float level will flood carb(s).
 

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Discussion Starter #8
i will try this tomorow. if the level goes above the o ring it means my something is wrong with my seat ?
 

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Remove the broken tip and fit a new mixture control screw. Idle screw broke off
Check the operation of the float needle valve and fuel level in the float bowl.
You might need to fit OEM needles. Aftermarket ones often give problems.
 

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Discussion Starter #10
i just tried for fun to bypass the acv on the LH by blocky the hole where the o ring sits with a section of a bigger o ring and put back the diafragm and spring back in. The bike idled without my hand on the throttle but the LH carb started to overflow. Ill bypass the RH acv tomorow and try it again but i think i found the culprit.
 

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Discussion Starter #11
Update. I bypassed both ACV (air cut off valves) polished the needle valve seat and carb cleaner sprayed the whole thing followed with compressed air. All my jets are clean etc. I started the bike up, it idled and i was able to drive it around my property for 20 min. Everything but those efin**** carbs is like new on the bike.

After the 20 min ride i put the bike on the side stand and it bogged down immidiately and right carb overflowed. Now i am back to square one. Not running unless I use the throttle and both carbs overflow.

I hope my rebuild kit from Keyster will resolve the problem. If not I will buy a murrays carb.

On another note. Anybody's got the model number for a oil filter i could buy at a normal autozone shop ?
 

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The 112 belongs in the brass emulsion tube - the 78 straight into the carb body. No wonder you're rich .... at least on one side.

As mentioned above the jammed mixture screw tip needs to be addressed.
 

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Discussion Starter #13
yup thats where i put them. is it possible that my carb are making kind of a vacuum sucking gas from the tank ? or is it just my needle valve that doesnt seal properly.
 

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Discussion Starter #14
The 112 belongs in the brass emulsion tube - the 78 straight into the carb body. No wonder you're rich .... at least on one side.

As mentioned above the jammed mixture screw tip needs to be addressed.
yup thats where i put them. is it possible that my carb are making kind of a vacuum sucking gas from the tank ? or is it just my needle valve that doesnt seal properly.
 

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No, but the overflow situation says that either your float levels are too high or the float needle has rust or other [email protected] caught in it.

You mention buying carb kits. If these are ebay items I suggest saving your money. The float needles will give incorrect levels and if you have full plastic floats the levels aren't adjustable. The original needle is ridiculously good quality and should be OK to continue to use. Ditto the brass parts. Nobody makes keihin parts like keihin.
 

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No, but the overflow situation says that either your float levels are too high or the float needle has rust or other [email protected] caught in it.

You mention buying carb kits. If these are ebay items I suggest saving your money. The float needles will give incorrect levels and if you have full plastic floats the levels aren't adjustable. The original needle is ridiculously good quality and should be OK to continue to use. Ditto the brass parts. Nobody makes keihin parts like keihin.
good to know. my float are black plastic and the tab where the needle valve hand on is metal. my needle were cleaned and the rubber actually looked very nice. should i bend the metal tab torward the needle seat and try again ?
 

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The float height needs to be set at 15.5 mm with the float tab resting on the needle but not depressing the plunger on the needle. {hold carb at 45 degree angle - not flat.

Fuel level can also be checked on bike with a length of 4 mm clear fuel line placed on the carbs float bowl drain barb and run up the side of the carb. With the petcock on loosen the drain screw a couple of turns. The level will show in the tube and should be about 2 mm below the carb to bowl joint.
 
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