Idle mixture screw woes.

10050 Views 20 Replies 6 Participants Last post by bandit, Feb 14, 2011

crackerjack

Discussion Starter · Jan 30, 2011

I'm currently cleaning and rebuilding my carbs with a kit I bought on ebay. Upon removing the old idle mixture screws / needle I discovered a problem. The needle is broken off from the threaded bit and wedged into the hole on one carb. Any ideas how to clear it?? What happens if I run the bike with those holes blocked?, ie. the idle screw tightened fully.

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LRCXed

· #2 · Jan 30, 2011

You need to get them out to make it run right. Do you see any of the tip sticking out in the venturi? I have use one of those plastic thumb tacks in a pair of vice-grip needle nose pliers to push them back out. Be careful though, not to damage the hole while your doing it. It takes a bit of force sometimes to get them unstuck.

This is such a common issue with these carbs that I made a special tool to get the broken tips out.

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crackerjack

Discussion Starter · #3 · Jan 31, 2011

Thanks for your advice LRCXed. The tip is just barely poking through. Enough that it makes it really difficult to balance anything on it to push down. I've been trying your suggestion of vice grips and thumb tack for hours and it's just not moving. What do you think about using a #74 drill bit from the other side to open it up again? I figure it's that or find some new carbs cause this thing isn't budging.

LRCXed

· #4 · Jan 31, 2011

NOOOOO, don't drill it. That hole and needle are tapered. If that's all that's wrong with them and you can't get them out I would be glad to get them out for you. Just cover shipping that's all. My tool has worked every time so far.

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crackerjack

Discussion Starter · #5 · Jan 31, 2011

LRCXed said:
NOOOOO, don't drill it. That hole and needle are tapered. If that's all that's wrong with them and you can't get them out I would be glad to get them out for you. Just cover shipping that's all. My tool has worked every time so far.

Wow that's very generous of you to offer! I'm going to keep trying and also talk to my local salvage to see if they have another set. I may take you up on it though. You're awesome.

Stan in Toronto

· #6 · Feb 2, 2011

I'm with Larry. NO drilling.

Call me.

Stan

crackerjack

Discussion Starter · #7 · Feb 2, 2011

Stan in TO said:
I'm with Larry. NO drilling.

Call me.

Stan

Too late. In a fit of frustration I drilled it out. Drilled the other side to match as well. I'm going to throw them on the bike and see how they behave. I'm grabbing another set on ebay as well in case my butchery has made these unusable. So this is now going to let a large amount of fuel through at idle?

bearman1

· #8 · Feb 2, 2011

The short answer would be, ya, man, ya prolly just ruined 2 carbs. HOWEVER, if you can find some larger idle screws to close up that larger hole you just bored through your carb bodies (can't BELEIVE you did that!), you MAY save them. And that's a pretty IFFY may.

Blue Fox

· #9 · Feb 2, 2011

I'm guessing that you won't be happy with the results. How large did you drill it out? You may be able to cut off a 3/8" bolt and taper it on a grinding wheel, get a O ring from a oil drilling rig, and see what happens. I suspect you now have a set of carbs that will serve only as a parts supply. Without a reference set, you will never know if things are at optimum.

But, I know the frustration level that sometimes creeps up. I can't count the number of fingerprints on the back side of parts that I "had" to touch to see if the paint was dry.

LRCXed

· #10 · Feb 2, 2011

How big was the drill bit you used? Like I said before, the hole WAS tapered. Not only do you not have any adjustability to the low end mix, but you'll probably find that you'll need to keep the screw all the way closed to get a lean enough mixture. That will depend on how big the hole is. They will run, but, more than likely too rich.

Which set of carbs did you buy as a replacement?

crackerjack

Discussion Starter · #11 · Feb 2, 2011

LRCXed said:
How big was the drill bit you used? Like I said before, the hole WAS tapered. Not only do you not have any adjustability to the low end mix, but you'll probably find that you'll need to keep the screw all the way closed to get a lean enough mixture. That will depend on how big the hole is. They will run, but, more than likely too rich.

Which set of carbs did you buy as a replacement?

How big? Let's just say that the opening is slightly larger now and certainly no longer tapered. I'm ashamed to admit the full extent of my stupidity. Since I clearly have you guys slack-jawed at this point how about I throw out another stupid idea I may actually try. If it runs, but it's now way too rich; What if I drill a small hole through the slide at the very top so that air leaks through only when it's resting?

I have no idea if what I've done will be totally fucked or not. I can live with my mistake if the carbs prove useless. I should mention that I recently took off the exhaust system, kept only the headers and threw on an extension piece from Canadian Tire on each side. I'm throwing an eye-bolt lollipop style baffle in there. The old exhaust was so rotten that when I went to remove the first muffler it literally broke in half where it joins the h-box on the first tug. The bike is outside under a tarp and I haven't had a chance to run it since doing any of this. At this poing I'm hoping this open header exhaust system will really like a lot of gas at idle??.. I'm not much of an optomist, but I'm trying here.

In the summer my bike got knocked over while it was parked. One of the problems that resulted from this was that the tiny spring on the choke linkage got knocked off. I fought with it to wind it around again, but it's never looked or responded right since. The point of mentioning this is that I could probably do with a nicer set of carbs anyhow.

I haven't ordered a new set yet, but there's two up on ebay at the moment that looks ok. Since you guys are being so forthcoming with your knowledge I'll ask a related question. I recently installed new gaskets on the float bowls, like a week ago. If I grab an old set of carbs on ebay can these new gaskets get moved over or are they toast?

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bandit

· #12 · Feb 2, 2011

i would say,gaskets etc would be fine.

post the bay links here so Larry can see what yur thinking of buying,and advice further

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crackerjack

Discussion Starter · #13 · Feb 2, 2011

http://cgi.ebay.ca/Honda-CX500-CX-5...rcycles_Parts_Accessories&hash=item19c2d66350

How about these? My bike actually has a GL500 engine does that make a difference?

LRCXed

· #14 · Feb 2, 2011

Since you don't have the bike you are working on in you're signature, what is it? A GL or a CX?

Those carbs will work for any CX std. or Custom, but I would stay away from them. Notice the corrosion in the left carb? It looks like they have had water sitting in them. It would be more work than it's worth. I would find another option.

Hmmm, straight headers, the richness of the lower end now that you've drilled it out may work to some degree. Put them on and let us know how it works.

crackerjack

Discussion Starter · #15 · Feb 2, 2011

LRCXed said:
Since you don't have the bike you are working on in you're signature, what is it? A GL or a CX?

Those carbs will work for any CX std. or Custom, but I would stay away from them. Notice the corrosion in the left carb? It looks like they have had water sitting in them. It would be more work than it's worth. I would find another option.

Hmmm, straight headers, the richness of the lower end now that you've drilled it out may work to some degree. Put them on and let us know how it works.

She's a 1981 CX 500 Custom with a GL500 Engine. I would love to go throw these in the bike and see how it goes, but we just got dumped on with snow and it's freakin cold out. There's a guy selling carbs in the buy/sell section that has 85/130 jets for $75. I've got 78/115 at the moment. Maybe these are a good score for me with the straight exhaust as well?

bandit

· #16 · Feb 2, 2011

crackerjack said:
She's a 1981 CX 500 Custom with a GL500 Engine. I would love to go throw these in the bike and see how it goes, but we just got dumped on with snow and it's freakin cold out. There's a guy selling carbs in the buy/sell section that has 85/130 jets for $75. I've got 78/115 at the moment. Maybe these are a good score for me with the straight exhaust as well?

as Larry said,go for it,put them on,whats the worse that can happen....it might end up the fastest cx.gl mix in the world

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crackerjack

Discussion Starter · #17 · Feb 2, 2011

bandit said:
as Larry said,go for it,put them on,whats the worse that can happen....it might end up the fastest cx.gl mix in the world

I like your attitude! I will definately be back with my findings as soon as mother nature let's me test em out. Thanks for not making fun of me too much guys!

bandit

· #18 · Feb 2, 2011

crackerjack said:
I like your attitude! I will definately be back with my findings as soon as mother nature let's me test em out. Thanks for not making fun of me too much guys!

good luck.

nobody pokes fun here,everyone is forever learning

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LRCXed

· #19 · Feb 2, 2011

Trust me Crackerjack, you are NOT the first one that's done that. I have 2 sets of carbs in my scrap pile that were done that way.

crackerjack

Discussion Starter · #20 · Feb 14, 2011

finally got a chance to load these carbs back in and run the bike. The choke seems totally useless now. I'm guessing it needs all the air it can get to deal with the larger amount of fuel. The engine fired with little fuss. I played with idle stop screw a bit slowly bringing the idle rpms down as the bike warmed up. My tach doesn't work so I don't know how many rpms I'm running at, but it has a nice low thumping idle with the straight pipes and my home-made baffles. What I really noticed was how much harder the bike pulls now. Time will tell if the bike is happy running like this. As the weather warms up here the story may change.

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