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87 CMX250
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Discussion Starter · #1 ·
This may be a really stupid question but I disassembled my carb awhile back and just now got everything back into place (or what I assume is back into place). I was wondering if I had these right so far. On the first photo I was wondering what and if the black piece screws into anything. The second one I was wondering if I had the hoses on correctly. Does the middle one just hang?

Thanks
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The black knob is on the idle adjustment screw. Once the engine is warm, adjust idle to 1,400 rpm + 100 rpm.

The tube in the second photo is the carb overflow/drain tube. There is a "Y" connector that joins the upper tube to the carb bowl drain nipple at the bottom of the carb. The hose is then routed to the right rear side of the engine in a wire loop that holds several tubes, including the puke tube. The puke tube should have a plug in it, and the contents should be drained when changing oil.
 
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87 CMX250
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28 Posts
Discussion Starter · #3 ·
This may be a really stupid question but I disassembled my carb awhile back and just now got everything back into place (or what I assume is back into place). I was wondering if I had these right so far. On the first photo I was wondering what and if the black piece screws into anything. The second one I was wondering if I had the hoses on correctly. Does the middle one just hang?

Update: after getting the carb back on with the tank and everything else she cranks like a dream. However instead of their being a gas leak where there was previously (due to a bad float) now it's leaking in another place. Would anyone know the cause of this? Did I put the screws in backwards? Would backwards screws even cause a leak?


Thanks
Photo 1 View attachment 111428





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The idle adjustment screw (black knob) is installed correctly. As it is screwed into the threaded section it passes through, throttle is advanced and rpms increase, and vice versa.

The arrows point to the accelerator pump. If it is leaking there, either the gasket portion of the pump isn't seated properly, it's cracked, or the screws aren't tight.
 
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1987 CMX250C AC
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accelerator pump diaphragm has integral seal around outer edge which is what your arrows are pointing to..
1st generation Rebel accelerator pump diaphragm is no longer available, But a CDV-101 diaphragm works if you cut shaft to match your bikes shaft length
 

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1987 CMX250C AC
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Least expensive place I found accel pump diaphragm a few years back when I replaced mine

haven't checked prices lately
 

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87 CMX250
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28 Posts
Discussion Starter · #7 ·
accelerator pump diaphragm has integral seal around outer edge which is what your arrows are pointing to..
1st generation Rebel accelerator pump diaphragm is no longer available, But a CDV-101 diaphragm works if you cut shaft to match your bikes shaft length
Ahhh ok, interesting. I did notice the rubber seal was pretty worn out and had I had a hard time getting it fitting correctly back into place because of this. There wasn't much rebound so it's likely stuck up in there. The part you linked, will that fit the 250? I see it's listed as for the 450.
 

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87 CMX250
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28 Posts
Discussion Starter · #8 ·
The black knob is on the idle adjustment screw. Once the engine is warm, adjust idle to 1,400 rpm + 100 rpm.

The tube in the second photo is the carb overflow/drain tube. There is a "Y" connector that joins the upper tube to the carb bowl drain nipple at the bottom of the carb. The hose is then routed to the right rear side of the engine in a wire loop that holds several tubes, including the puke tube. The puke tube should have a plug in it, and the contents should be drained when changing oil.
Am I missing some tubes then? Do you mind showing me a photo of what it's supposed to look like? If that's the case it hasn't been connected correctly in...who knows how long
 

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1987 CMX250C AC
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missing float bowl drain tube as far as I can see
While this is image of 2nd gen Rebel carb the vent and drain tubes are the same for all
You could just add an additional tube to bowl drain/overflow nipple rather than search for Y connector..

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Back that idle adjustment screw off so it doesn't touch contact point.. than screw in so arm where it touches raises a millimeter or two... That screw is opening the throttle plate ever so slightly..
 

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1987 CMX250C AC
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there isn't much movement (deflection) of accelerator diaphragm when new
Yes the CDV-101 diaphragm fits perfectly Except the Shaft has to be cut to length for the Rebel
This page is where I first found the CDV-101 would work on 1st generation 85-87 Rebels..


works perfectly on my 87 having cut the shaft shorter to match what I took out
my middle name is cheap, it's why I used the other supplier..
 

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87 CMX250
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28 Posts
Discussion Starter · #12 ·
there isn't much movement (deflection) of accelerator diaphragm when new
Yes the CDV-101 diaphragm fits perfectly Except the Shaft has to be cut to length for the Rebel
This page is where I first found the CDV-101 would work on 1st generation 85-87 Rebels..


works perfectly on my 87 having cut the shaft shorter to match what I took out
my middle name is cheap, it's why I used the other supplier..
What do you mean by deflection? I'm new to all this... Which part is the shaft and how much shorter does it need to be? Thanks so much, this is all very helpful
 

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87 CMX250
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28 Posts
Discussion Starter · #13 ·
missing float bowl drain tube as far as I can see
While this is image of 2nd gen Rebel carb the vent and drain tubes are the same for all
You could just add an additional tube to bowl drain/overflow nipple rather than search for Y connector..

View attachment 111435

Back that idle adjustment screw off so it doesn't touch contact point.. than screw in so arm where it touches raises a millimeter or two... That screw is opening the throttle plate ever so slightly..
Ohhh I see. The bottom of the Y tube doesn't connect to anything though? It just hangs there?
 

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1987 CMX250C AC
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deflect = amount of movement
if you hit a drum the surface deflects back and forth..

At the time i didn't measure how much I cut from New accelerator diaphragm shaft..
S.C.I. indicates the shaft is 89.46 mm long on their web page.. I cut 24mm or more off it's length (I think), you'll have to measure your old accelerator pump shaft to obtain proper length..
 
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1987 CMX250C AC
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Ohhh I see. The bottom of the Y tube doesn't connect to anything though? It just hangs there?
no the bottom of Y connector has hose attached that continues down below frame along with the other rubber hoses..
 

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The hose(s) are routed to carry gasoline leaking from the carb to behind the rear of the engine, where it would drip out onto the road. Leaking gas on a hot engine could be a flammable combination.
 

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87 CMX250
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28 Posts
Discussion Starter · #18 ·
deflect = amount of movement
if you hit a drum the surface deflects back and forth..

At the time i didn't measure how much I cut from New accelerator diaphragm shaft..
S.C.I. indicates the shaft is 89.46 mm long on their web page.. I cut 24mm or more off it's length (I think), you'll have to measure your old accelerator pump shaft to obtain proper length..
Thanks so much!
 

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2006 CMX250C
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This may help others as to the tube/hose connections and routing. When I was looking it wasn't easy getting all the pieces.
I added my comments to a photo someone else posted.
Moderators if this is helpful perhaps a sticky section could be added to the forum.
Thx
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1987 CMX250C AC
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This may help others as to the tube/hose connections and routing. When I was looking it wasn't easy getting all the pieces.
I added my comments to a photo someone else posted.
Moderators if this is helpful perhaps a sticky section could be added to the forum.
Thx
What you have labeled "To Carb overflow" is float bowl vent which prevents a vacuum from forming in float bowl..
The float bowl overflow and drain utilize the same nipple labeled "to the bottom of carb" in the image.. yes the vent and overflow/drain hoses are interconnected by Y connector, though they could be separately routed under frame if Y connector is broken or removed.

if you have tube over the top of carb it appears you may have remnants of carbon canister purge control valve connection indicated by hose #5 which may have been removed..

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there are 2 distinct carb hose systems and associated carburetors..
Hose #11 connects to brass nipple to right of mixture screw..

Image of carb with plugged vacuum and purge nipples circled..

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