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PostPosted: Wed Jul 16, 2008 3:46 am 
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Joined: Sep 13, 2007
Country: USA
State/Province: MD
City: Woodsboro
Simple stuff...

First, the Petcock (Fuel control valve) has two nipples on the back. The one closest to the engine is the one you want. If you hook it up wrong it's not a big deal. You just won't get fuel so switch it. The hose goes from the petcock to the nipple at the top of the left cylinder.

Right cylinder nipple attaches to the air cut-off circuit. Hose comes off the nipple, attaches to a Tee connector. From the Tee the hoses go to both the right and left air cut-offs. When routing the hose for the left carb, you have to kind of snake the hose up and around the choke cable. Make sure it doesn't bind any of the cables. The air cut-off nipple on the carb is the one attached to the round cap held on with two screws.

The overflow tubes are the curved metal tubes on the sides of the carb. Normally there are two figure 8 washers that hold these tubes. One hole of the 8 attaches in the back corner of the vacuum chamber lid. The other hole of the 8 is where the overflow tube goes. You then route these two tubes behind the transmission where the large black air breather vent tube from the valve cover goes. It's basically directly in the middle of the bike, between the two carbs and just behind the transmission.

That's about it! If that doesn't help enough let me know and I can go out and snap some more pics! :-) Good Luck!

_________________
Do you know what it's like to fall in the mud and get kicked, in the head, by an iron boot? Of course you don't--no one does--that never happens. - Capt. Rex Kramer

1986 Honda CMX450C - Jola
1978 Honda GL1000 - Piper


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 Post subject:
PostPosted: Wed Sep 17, 2008 1:39 pm 
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Joined: Sep 17, 2008
One more quick question on this topic. When using the manometer to balance the carbs where do I connect my hoses?

Excellent write up by the way.


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 Post subject:
PostPosted: Wed Sep 17, 2008 1:53 pm 
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Joined: Sep 13, 2007
Country: USA
State/Province: MD
City: Woodsboro
When I hooked up my manometer, I hooked one to the nipple on the right side cylinder, the other hooked to a tee and put one end on the petcock and the other on the left cylinder nipple.

_________________
Do you know what it's like to fall in the mud and get kicked, in the head, by an iron boot? Of course you don't--no one does--that never happens. - Capt. Rex Kramer

1986 Honda CMX450C - Jola
1978 Honda GL1000 - Piper


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 Post subject: toughness of vacuum valve
PostPosted: Wed Oct 29, 2008 8:08 pm 
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Joined: Apr 11, 2008
Country: USA
State/Province: FL
City: Miami
hey guys, going through my carbs and noticed one of the smaller vacuum diaphragms has a lot of resistance when moving up and down, it's the one on the float chamber

should this thing be moving freely, or what? i need to pull on it hard for it to move, and it doesn't spring back when i do

here's a picture of the one i mean

ImageImage


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 Post subject: never mind...
PostPosted: Wed Oct 29, 2008 8:37 pm 
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Joined: Apr 11, 2008
Country: USA
State/Province: FL
City: Miami
i'm dumb - had missed the spring that goes inside it


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 Post subject:
PostPosted: Thu Oct 30, 2008 3:15 am 
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Joined: Sep 13, 2007
Country: USA
State/Province: MD
City: Woodsboro
Just for reference, that diaphram is the accelerator pump.

_________________
Do you know what it's like to fall in the mud and get kicked, in the head, by an iron boot? Of course you don't--no one does--that never happens. - Capt. Rex Kramer

1986 Honda CMX450C - Jola
1978 Honda GL1000 - Piper


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 Post subject: Great Job
PostPosted: Tue Jan 20, 2009 8:26 am 
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Joined: Jan 18, 2009
Any chance that the dual carb setup fits on the 250? with a little re-jetting/cam changes? - what it's already got two intake ports right?? NOT FAIR you get two pretty carbs.. :cry:

Cheers!
Rob in NH

_________________
Building a Chopper around the CMX250 Engine (See my profile for a link to the 52 Videos on it)
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"GOOD thing's aren't CHEAP and CHEAP thing's aren't GOOD - But FREE thing's ROCK!" -Rob


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 Post subject:
PostPosted: Wed Jan 05, 2011 10:07 am 
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Joined: May 26, 2008
Hi, that's a great contribution to the forum and for a rookie like me. I have a few doubts.

-can anyone show me in the pic which is the non-adjustable float, the float valve (that I guess is the brown plastic piece with the two floats) and the pin.

-how I do to take the float height to the acceptable tolerance of 18.5mm.

thanks for your help.


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 Post subject:
PostPosted: Wed Jan 05, 2011 5:53 pm 
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Joined: Feb 23, 2009
Motorcycle: Rebel 250 plus a few others
Rebel: 250
Country: Canada
State/Province: NB
City: Fredericton
The gold colored pin in the bottom front of the brown float(as photographed, the pin is really above the float when installed) is the actual fuel cutoff pin. It has a conical tip which the float presses up into a hole where the fuel enters the float bowl. The conical tip shuts off the flow when the float presses it up into the hole.
With the carb body upside down, gravity will push the floats down (up when installed) simulating a full float bowl and force the conical tip of the pin into the fuel feed hole. The float clearance is measured from the bottom (top) surface of the floats to the gasket surface of the carb body.

Lay a straight edge across the floats and measure the shortest distance between the straight edge and the carb body. IF the clearance is too small the writer talks about changing the shim between the fuel cutoff pin and the float. In the old days this was usually a bendable metal tang that could be adjusted, but this one appears to be non adjustable except by shimming.

A smaller than required clearance will result in a RICH mixture, since the fuel level in the float bowl will be higher than necessary.

_________________
2004 Honda Rebel 250
2003 BMW K1200GT
2004 BMW R1200GS
1996 Ducati 900SS
1973 Norton 850 Interstate


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 Post subject:
PostPosted: Thu Jan 06, 2011 8:47 pm 
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Joined: May 26, 2008
WOW Sir. that was very helpful. I have a carb with a leak problem in the left side float bowl, sometimes leak and some others not, and I was thinking to fix it myself. maybe I post aging for further information. I am very grateful for your help, THANKS. :D


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 Post subject:
PostPosted: Thu Jan 06, 2011 11:13 pm 
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Joined: Dec 5, 2010
Motorcycle: 1986 Honda Rebel 450
Rebel: 450
Country: USA
State/Province: MD
City: Bowie
RebelBoy wrote:
WOW Sir. that was very helpful. I have a carb with a leak problem in the left side float bowl, sometimes leak and some others not, and I was thinking to fix it myself. maybe I post aging for further information. I am very grateful for your help, THANKS. :D

If you mean the carb was leaking from your overflow, I JUST fixed that issue 1 week ago, it was the float needles.

_________________
1986 Honda Interceptor 1000 V-Four (VF1000f)
1983 Honda Shadow VT500C (sold)
1986 Honda Interceptor 500 V-Four (VF500F)
1993 Honda Nighthawk 250
1984 Honda V65 Magna
1981 Yamaha XS400 Special
1986 Honda Rebel 450 (project)


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 Post subject: Re: 450 Carburetor Pictorial
PostPosted: Sun Jan 09, 2011 10:14 pm 
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Joined: May 26, 2008
thanks, I'm thinking in get a new float, needles and maybe upgrade the jet to 135. I replace the air filter box for the small air filter pod and most of what I read recommend to upgrade the jet. If some know where to buy the floats etc. online , please let know. all i found was this web page. http://www.motorcyclecarbs.com/CARBURETOR_REPAIR_KIT_HONDA_C_P16550.cfm


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 Post subject: Re: 450 Carburetor Pictorial
PostPosted: Mon Jun 06, 2011 1:20 pm 
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Joined: Jun 5, 2011
Motorcycle: '85 CMX250
Rebel: 450
Country: USA
State/Province: CA
City: Moorpark
A great tutorial. Clearer description and crisper photos than any service manual I've ever read. A thousand thanks to the author for this one.

One small comment on the photo of the bowl area.

<This is the fuel bowl area. Here's what you're looking at starting from the top and moving downwards. . . I'm not sure what the last hole is used for. I belive it's a fuel return and has something to do with the air cut-off circuit. . .>

In cleaning my carb yesterday, I convinced myself that the "last" hole feeds the choke/enricher valve. I'm just a beginner at this, so I'll let more experienced voices confirm or correct me on this. But maybe the added detail will help out the next beginner.

Thanks guys.


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 Post subject: Re: 450 Carburetor Pictorial
PostPosted: Sun Aug 06, 2017 6:35 pm 
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Joined: Aug 6, 2017
Motorcycle: Honda
Rebel: 250
Country: USA
State/Province: OH
City: Whitehouse
paultjack, if you're still following your post, I just wanted you to know I also appreciate the thoroughness of the info. I'm helping a friend restore a '87 250 Rebel and have taken the time to read all of this and clean and restore the (single) carb. I'll be installing it back on the bike tomorrow. It wouldn't accelerate the first attempted cleaning, but it wasn't a complete cleaning. I'll let you know here, what my result is after getting it back together. Thanks again!


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 Post subject: Re: 450 Carburetor Pictorial
PostPosted: Mon Aug 07, 2017 12:27 pm 
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Joined: Sep 13, 2007
Country: USA
State/Province: MD
City: Woodsboro
That's awesome! It's wonderful to know that something I wrote so long ago is still helping. I still have my 450. I love that bike! I found some carbs (from China) that might work as replacements for the 450 carbs. They're about $50 each, new so I'm not going to try them unless absolutely necessary. But I thought it was cool to find something that might work.

Let me know how it goes! Remember, any dirt in the slow jets will... Well, you know! LOL

_________________
Do you know what it's like to fall in the mud and get kicked, in the head, by an iron boot? Of course you don't--no one does--that never happens. - Capt. Rex Kramer

1986 Honda CMX450C - Jola
1978 Honda GL1000 - Piper


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