Topic: Dust Plate broken on CB500 carbs

[jkminer]

I am rebuilding my 71 500 carbs and i noticed that the dust plate between carbs 3 and 4 is broken.  Is this a probem?   I can easily make another one i just wanted to know if it mattered enough to replace.  I am using the term dust plate from he manual, its a strip of aluminum that connects the linkages together between carbs 1 to 2 and 3 to 4.  Thanks for the input.

[Laminar]

Is this the part you're talking about?


I believe I have a spare one if you want it.

[jkminer]

yeah that's the part, i can easily make some out of some scrap metal i have, I guess i just want to know its purpose, and if its worth replacing.  thanks

[JBMorse]

As far as I can tell, it simply limits side to side movement of the adjuster holders as the throttles move up and down.
 When I did my most recent carb sync, I realized that these adjusters are sensitive, even applying too much pressure with the adjustment tool can cause erratic throttle behavior.  I had to to everything gently to get good readings on my gauge.
So yes, I do recommend replacing them.  Here's how I did it, but you could probably use almost any thin scrap metal. http://forums.sohc4.net/index.php?topic=65007.0
Good luck!

[TwoTired]

I believe the "dust plate" is made of stainless steel. FYI

 (I can think of some possible reasons; Keeping the linkage parallel and therefore all the slides in equal relative position, keeping those rubber dust seals effective, also possibly a vibration lock to hold the adjustment.) 
I've never actually seen a mechanical justification for it's existence.  Neither have I seen a justification for removal, besides "I don't wanna".

I do know that engineers usually don't add anything to a machine that isn't required or have a specific function, as saving $1 on any part additions is significant when you are making and selling 1 million bikes.  You can employ 5-10 engineers for that money saved (or one extra executive).   

Unless you are a bike customizer or a bike fabricator, there are usually few things on a bike made by engineers that aren't there for a reason, even if you can't fathom it.

Yes, the carbs will "work" without that "dust plate".  I don't think anyone really knows the repercussions of NOT using it.  You could be the pioneer, and maybe nothing bad will happen while it is in your custody?

[jkminer]

The reason im taking the carbs apart and rebuilding them is they were consistently running rich, especially cylinder 3, which is one of the cylinders that the link is broken on.  I have some galvanized sheet metal i can make one out of real quick.  On another note none of my carbs have the springs in the bowl mentioned or shown in the manuals.  I guess they're there to hold the jets in place.  Everything else is there.  But none of the carbs have them.  Are they necessary?

[number13]

Are they necessary?

Yeah, they hold the main jets
in place. You need them.

[crazypj]

My 550 ones broke, I removed them. didn't notice any difference in 20~30,000 miles

PJ

[Ms Tokyo]

Anyone have a source for the rubber dust seals or if you have fabbed your own, what did you use?