Topic: '74 CB550 carb question - newbie here

[AdamF]

Hello, everyone. Newbie here so bear with me....

I purchased a '74 CB550 from by brother for $360 and am at the very beginning stages of building a brat bike. I've taken the carbs off and cleaned them pretty well (evaporust is awesome, buy the way). In doing so, I found out that the rubber pieces that wrap around the pieces that hold the carbs together were bad and need to be replaced. This may be a stupid question but does anyone know where to find those? Are they super specialty or something that you can pick up from auto zone or something?

Also, another potentially stupid question is: does anyone have any tips on rebuilding the carbs? I bought a rebuild kit and understand pretty much how to put it together (bought a video from howtomotorcyclerepair.com. Is there anything that I should have on hand before attempting? Do you put something to hold the gaskets on or just pressure?

Thanks in advance for any help!

[Scott S]

 Keep and re-use the original brass. Just use the O-rings from the kits.
 Just pressure will hold the gasket, but you can use a dab of glue or grease to hold them in place. 4into1.com sells nice, shaped bowl gaskets.

[AdamF]

Scott,

That's where I got the rebuild kit. I have heard people say to use the original brass. Why is that? The new brass pieces that I go tin the kit look the very same and are in much better shape. Is it something about the quality of brass? Some of the older pieces are horribly dirty (emulsifier tubes, etc.).

Also, I did buy 110 jets as I am going to pod filters and probably a 4 into 1 exhaust.

Again, dumb question but what type of grease or glue? Is there a specific kind?

Thanks for the help!

-Adam

[Scott S]

 Super glue or all purpose grease. Just a dab. If you have the shaped gaskets, you probably won't need it.

 If you have the air box, use it.

[uncle_fester]

FWIW, I have a '74 CB550 with pods. 105 mains with 40 pilots worked. I also tried moving the needle one step richer, but that was too much. The factory original position worked best.

I second the original brass. If necessary, use Jets-R-Us for the jets. They worked well for my application.

[AdamF]

I went with the 110s because I am going to use pod filters and a different exhaust. I based that decision off others building a similar bike and their recommendation.

Does anyone have any input as to the rubber prices that wrap around the parts that hold the carbs together? Mine were brittle and shot. I'll have to replace them before I move on.

Thanks!

[dave500]

soak your old brass parts in vinegar,the new parts look all nice and shiny but the those tiny holes here and there where fuel passes through are often out of spec,your engine will run with them but your going to have enough trouble setting up pods as it is,someone may have told you that say 110 jets work good but if they used cheaper aftermarket jets they may actually have a diameter of 111 or perhaps even 108?

[AdamF]

Calj,

Thanks for the link. The rubber piece that I am trying to describe is part of the holder set. The other pieces are in great shape but I need new rubber. Anyone know where to find just the rubber pieces? I'd rather not drop big money on replacing the entire unit when everything else is good.

Thanks all for the input!

[flybox1]

Calj,

Thanks for the link. The rubber piece that I am trying to describe is part of the holder set. The other pieces are in great shape but I need new rubber. Anyone know where to find just the rubber pieces? I'd rather not drop big money on replacing the entire unit when everything else is good.

Thanks all for the input!

Still dont know what rubber pieces you are describing.  post up a picture of the damaged part pls.

[AdamF]

Here is a picture of the part. It is the rubber pice that wraps around the metal piece. They were old and brittle and came apart during the disassembly. I really hope they are available for individual purchase.



Thanks in advance for all of your help. Wish I could have described it a little better.

-Adam

[MetroRedneck]

I believe those were intended as a dust shield.  Doesn't hurt to leave them off.

[Scott S]

 You can leave them off or cut a similar piece from an old inner tube.

[dave500]

I leave them off.

[spanners]

Not available any more, although you will find people out there selling old ones, they will be brittle.  As mentioned they were designed to keep grit out.  I dare say you can leave them off, but if a things worth doing.... I felt better having a go and replacing them with some simple made separate washers rather than not fit them at all.   I used a wad punch to make some separate round rubber washers up out of some 1.5mm sheet rubber.

[dave500]

people have used old inner tubes for them,they don't have a real good seal anyway,i guess its the thought that counts?