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Discussion Starter · #1 ·
Well, I was able to get the carburetor off. In the process, the paper gasket between the carb and the intake manifold fell apart. The mating surface of the carb has some scratches.

Is it serious damage? I also found oil slick in the air box and frame of the air filter. It seems that oil got in there. I just bought the bike. It had sat for more than a year under a deck. It ran only with choke and had trouble accelerating. Compression after warm up is 160 psi left and 150 psi right. When I checked oil level, it was high. I had to remove about a cup of oil. The oil level might have been high when I test drove it. It seems the seller had changed oil recently as it looked very clean. The air filter looks new too it must have been exposed to oil as I keep feeling oil on the edges where paper meets the metal frame.even after repeated cleaning.

The Chemdip I bought says it's safe for rubber and plastic. Do I have to remove the o ring that goes between the intake manifold and the carb when I woke it in chemdip? Where do I find a new o ring?
I have never worked on a carb before. I am sorry for asking stupid questions.

Thanks in advance for help.
IMG_20210630_233806.jpg
 

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1986,Honda rebel 250
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No question is stupid I wouldn’t put the rubber or plastic parts on the chem dip
As it may eat them. You’ll want to move the parts around too to make sure it really soaks all the holes this can take a few days. When your done rinse them well and use a air gun to make sure there is no water in passages. Good luck with getting your rebel going.
 

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Discussion Starter · #3 ·
What is this screw (in the center of the frame?) with a tab and a slot for a flat blade screwdriver?
IMG_20210701_001847.jpg
 

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Discussion Starter · #4 ·
No question is stupid I wouldn’t put the rubber or plastic parts on the chem dip
As it may eat them. You’ll want to move the parts around too to make sure it really soaks all the holes this can take a few days. When your done rinse them well and use a air gun to make sure there is no water in passages. Good luck with getting your rebel going.
Thanks 86 rebelre. I shall follow your advice. Are scratches on the surface of the carb that mates with the intake manifold surface troublesome? I am hoping a new gasket should take care of those imperfections.
 

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05 Honda CMX250C | 93 Kawi VN750
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The tabbed flathead screw is your fuel/air mixture screw. You can safely ignore it, just be sure not to adjust it when the float bowl is off. The tab is to keep it from migrating out of tune.

The intake o-ring isn't special, just make sure you match the size. Auto parts stores have metric o-rings that will do fine - it's 2.4x29mm.
 

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Discussion Starter · #6 · (Edited)
The tabbed flathead screw is your fuel/air mixture screw. You can safely ignore it, just be sure not to adjust it when the float bowl is off. The tab is to keep it from migrating out of tune.

The intake o-ring isn't special, just make sure you match the size. Auto parts stores have metric o-rings that will do fine - it's 2.4x29mm.
Thank you for answering my question and enlightening me. I did think that the tabbed screw was the air/fuel mixture screw set at factory but I didn't know for sure. On my Honda lawn mower it's just a plug, which had to be drilled out to access the fuel/air mixture screw. As I said before, I have never worked on a carburetor accept on my Honda lawnmower. I am in my 60s but its never too late to learn.

If the O ring looks good and pliable, can I reuse it? The same question for the float bowl gasket and the o ring on the accelerator pump hole?

As for the intake manifold gasket, I found a pack of 4 different sheets of gasket material an Amazon.

Fel-Pro 3060 Gasket Material

Here is what the 4 sheets are:
One cork-rubber sheet = 10"x 8 5/8" x 1/8"
One cork-rubber sheet = 9 1/8" x 8 5/8" x 1/16"
One rubber-cellulose sheet = 9 3/4" x 8 5/8" x 3/64"
One rubber-fiber sheet = 9 1/4" x 8 5/8" x 1/32"

Can any of these sheets be used to make the intake manifold gasket? I have doubts about the first two. I remember replacing the valve cover gasket on my 1970 Opel Kadett, which was made of either cork or cork and rubber.

P.S. I just measured the thickness of the paper gasket that fell apart. It's .014-.015 inch (.36 mm) thick, which is about 1/64 inch. I suppose it was compressed. So 1/32 is probably a good thickness as long as the material is suitable for intake gasket.

I have been calling it intake manifold gasket but apparently it's the gasket between intake plenum and the carburetor.

I have also found
1/32 " Felpro Gasket Material
Individual Karropak gasket material sheet 1/16" x 12" x 36"
and
Felpro Rubber-fiber gasket material 1/32" x 10" x 26"
and
Rubber-fiber gasket material 1/16" x 10" x 26"

Any guidance as to which one is suitable for the gasket between intake plenum and the carb, would be greatly appreciated. I hope I am not being too much of a pain.
 

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05 Honda CMX250C | 93 Kawi VN750
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You're certainly not being a pain - I'm happy to share accumulated experience and knowledge.

I use FelPro's 3157 (rubber fiber, 1/32" I think) for pretty much all of my custom gaskets. It seals well enough for my scuffed up intake manifold's inlet, but it's also more of a dust gasket, I believe - the o-ring does all the air/fuel sealing.
As long as you can tug on your o-rings with light pressure and they're not too compressed, I see no problem re-using them.
 

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The big O-ring shouldn't need to be replaced as long as it isn't damaged. I would remove the air/fuel screw as there is a rubber O-ring on it that could be damaged in the Chem Dip. Be sure not to lose the small washer and spring that are on the screw. You'll need to adjust the screw before installing the bowl as the tab on the bowl will prevent the screw from being turned out sufficiently. The initial setting for second generation models is 2 3/4 turns out from lightly seated.
 

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Discussion Starter · #9 · (Edited)
110724


For Honda Rebel 250 Parts Carburetor Rebuild Kit, for Honda Rebel 250 CMX250CL California CMX250C 49 State CMX250CD Limited, 0201-318


Thanks flitecontrol.
I am trying to identify bits and pieces in this picture of a kit sold by Amazon. What's the piece top row 2nd from right? From what I have read here, it seems like it has bits and pieces for both first and 2nd generation. IS it clear from the picture whether it contains the o ring, and spring air fuel mixture screw? I can see the air-fuel mixture screw. I am dreading playing with it. AM I correct in assuming that the tabbed screw is not the air-fuel screw? And that he actual air-fuel screw spring, or ring washer or whatever are under the tabbed screw? I see why there is a tab on that screw. You have to undress the carb before you do any touchy feely with the air-fuel screw. I will also count the number of turns it takes to bottom out before I remove it.

I am cautious as a motorcycle rider ought to be. Thank goodness for internet and this forum. There were no resources like this when bought my first car in 1979. All I had was Clymer's manual, and a an English friend, who happened to have the same car. He taught me how to change bake pads. Before that, all I had done was change clutch and throttle cables on a two stroke Vespa, change and or re-gap the spark plug, clean the air filter and mess around with the carb with np clue as t what I was doing. I thank you all.

I am not done yet. I am sure I shall have more questions.
 

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05 Honda CMX250C | 93 Kawi VN750
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Top row 2nd from the right is your needle jet seat, it's installed in the carb body before part #22 in this diagram (concave side up). The small o-ring next to the washer on the left are for your air/fuel screw.

EDIT: Forgot to mention, the screw with the plastic cover is your mixture screw. Aftermarket ones don't come with the tab. Some folks use a bit of putty over the top after installing to keep it from migrating.
 

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Discussion Starter · #11 ·
Top row 2nd from the right is your needle jet seat, it's installed in the carb body before part #22 in this diagram (concave side up). The small o-ring next to the washer on the left are for your air/fuel screw.

EDIT: Forgot to mention, the screw with the plastic cover is your mixture screw. Aftermarket ones don't come with the tab. Some folks use a bit of putty over the top after installing to keep it from migrating.
Thank you drakoala. I think I will understand better when I start dismantling the carb. A part of my confusion arises from different terminologies. In the diagram #22 is called needle jet holder, which as I understand, is the same thing as emulsion tube (with holes) and part #2 is labeled as needle jet, set ( it refers needle and seat as needle jet set). It's probably a typo. Whatever it is my understanding, based on your explanation is the needle jet holder (#22 emulsion tube) sits on top of the main jet; the seat on top of #22 and the needle slides in an out of both the seat and the tube. Is that correct?

Secondly, there are two springs in the picture I pasted above. I assume one is for the air/fuel mixture screw. Is the second screw for carburetor drain screw or is it something else? I want to understand proper place and function of all the parts in the picture I pasted. F\

Float bowl gaskets: one with o-ring moulded with the gasket and the other without and with a separate o ring. When I dismantle the carb, I will know which one is to be used.
 

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Discussion Starter · #12 ·
I thought I should add pictures of my bike. Here are two before I cleaned it up.
IMG_20210616_211946.jpg
IMG_20210616_211917.jpg
 

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Discussion Starter · #13 ·
You're certainly not being a pain - I'm happy to share accumulated experience and knowledge.

I use FelPro's 3157 (rubber fiber, 1/32" I think) for pretty much all of my custom gaskets. It seals well enough for my scuffed up intake manifold's inlet, but it's also more of a dust gasket, I believe - the o-ring does all the air/fuel sealing.
As long as you can tug on your o-rings with light pressure and they're not too compressed, I see no problem re-using them.
DO I need to use any adhesive with this gasket?
 

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85 CMX 250C, 82 GW Remember that you are invisible, treat all others accordingly. Avoids Road RAGE!
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It may not make a difference, but at my previous work, specifically on rubber grommets they told us all ways to use vegetable oil (like Crisco)! not silicone. The reason was that silicone or petroleum- based grease could deteriorate the rubber O-rings.
However I will defer to people who are much more experienced with the Honda Rebel carburetors.
 

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The O-rings and bowl gasket are nitrile, and should be resistant to petroleum based products (like gasoline!) I've used a dab of Vaseline or wheel bearing grease to hold the bowl gasket and jet diaphragm in place while installing. If the lip on the diaphragm doesn't want to seat, it's usually because the rubber tends to shrink over time. A diluted solution of Oil of Wintergreen or a light application of brake fluid will swell the rubber bits back to new. I wouldn't use any adhesive, even though they do in the factory. If it seats properly, there's no need.

The O-rings inside the bowl gasket are for the carb drain screw (larger) and air/fuel screw, as is the washer. The spring(s) are for the air/fuel screw. The used air fuel spring I have in hand has six coils as I count them, and is right at 9mm long. Looks like the ones in the picture have five and eight coils. I'd use the one closest to 9-10 mm.

The brass parts are from the left, are needle, air/fuel screw, slow jet, needle jet, and main jet. If you use the new needle jet, also use the supplied needle as they are a set and can vary slightly from the stock parts.

Not sure why they supplied two bowl gaskets. On the first generation carbs, the O-ring was separate from the gasket, and on the later models they made it all one piece. For those with a first gen carb that may be reading this, the gasket with the O-ring attached can be used. Just carefully cut the O-ring off the rest of the gasket, making sure you don't cut off too much of the O-ring.

Think this covers all your questions, but feel free to ask if you have more.
 

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Flite, I have to imagine they supply two bowl gaskets because the CA250 (most kits on eBay and Amazon are for the Chinese clone) is dual-carb. But there's only one of each jet... Maybe it's just a spare, dunno. 🤷‍♂️

...The reason was that silicone or petroleum- based grease could deteriorate the rubber O-rings...
Silicone based lubricants are directly compatible with nitrile (the preferred rubber for o-rings) - and are often used to preserve nitrile. Petroleum grease, unless mixed with cleaning additives like acetone (i.e. aerosol carb cleaner), should have no noticeable effects on nitrile, otherwise it wouldn't be a suitable material for a seal against gasoline. The worry with petroleum greases is that they can coagulate and clog passages in the carb.
 

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Thank you for the clarification. The equipment that I was used to, was made of a different material. And also for a different purpose.
If I had thought about it a little bit more, I would have recognized gasoline is in the carburetor.
(Sometimes the brain is not fully engaged before the mouth is in gear.)
Therefore, petroleum distillates would not be too much problem.
 

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Discussion Starter · #18 ·
Well, I was able to get the carburetor off. In the process, the paper gasket between the carb and the intake manifold fell apart. The mating surface of the carb has some scratches.

Is it serious damage? I also found oil slick in the air box and frame of the air filter. It seems that oil got in there. I just bought the bike. It had sat for more than a year under a deck. It ran only with choke and had trouble accelerating. Compression after warm up is 160 psi left and 150 psi right. When I checked oil level, it was high. I had to remove about a cup of oil. The oil level might have been high when I test drove it. It seems the seller had changed oil recently as it looked very clean. The air filter looks new too it must have been exposed to oil as I keep feeling oil on the edges where paper meets the metal frame.even after repeated cleaning.

The Chemdip I bought says it's safe for rubber and plastic. Do I have to remove the o ring that goes between the intake manifold and the carb when I woke it in chemdip? Where do I find a new o ring?
I have never worked on a carb before. I am sorry for asking stupid questions.

Thanks in advance for help. View attachment 110722
Well, I ordered the gasket material for the gasket that goes between the carburetor and the intake plenum. Should the gasket the O ring completely, to the edge of the intake, or should it extend only to the outer edge of the O-ring and notcover the O-ring. My feeling is that it should not cover the O-ring since it might interfere with the sealing. But when I look at the gasket here and measure dimensions on my screen and scale them up to the size of various holes and studs, the conclusion I reach is that the gasket should cover the O-ring. Since I haven't got an OEM gasket, I am confused.
 
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