Author Topic: HONDA 500/4 later carbs?  (Read 804 times)

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rustybones

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HONDA 500/4 later carbs?
« on: April 20, 2009, 10:58:46 AM »
Hello. Very new here so go easy on me...  ;)
I recently got myself a 1973 Honda 500/4. It started OK for a little while then slowly got worse and worse until it wouldn't start at all. I found a leak on one of the float chambers and also that petrol was coming down one of the overflow pipes on another. So after stripping the carbs and cleaning the idle jets and float needles it ran good again. For a day or so....  ::) I guess there's crap in the tank and it blocked them again....

So I stripped them down again and had a really good look - seems like the carbs are really crapped up inside and there's a lot of movement in the brass inserts that push in around the float needle etc. So my question is this - can I put any later model carbs into this bike? I've looked around for service parts and seems they're few and far between and I'd spend less putting a newer set in than trying to sort out the existing ones?
Thanks in advance for any help!

Offline cleveland

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Re: HONDA 500/4 later carbs?
« Reply #1 on: April 20, 2009, 11:45:20 AM »
I'm pretty sure you can use later carbs, but you may have to swap out the jets.

As for the crap going from the tank to the carbs, pick up an inline fuel filter.  Best $3 I ever spent.  ;D

Offline bwaller

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Re: HONDA 500/4 later carbs?
« Reply #2 on: April 20, 2009, 12:22:27 PM »
I've just sold all my extra 500 carbs, but they are easily available for short money.

Offline number13

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Re: HONDA 500/4 later carbs?
« Reply #3 on: April 20, 2009, 12:45:28 PM »
500 and 550 carbs are nearly identical, except for the jetting.
All over e-Bay for cheap.
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Offline SteveD CB500F

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Re: HONDA 500/4 later carbs?
« Reply #4 on: April 21, 2009, 03:33:55 AM »
A cheap set from eBay is a good idea for spares, but don't expect any purchase of old carbs to be any better than the one's you have now.

What exactly do you mean by the brass inserts? (pictures?)
If you mean the main jets, they get loose when the o-ring hardens or perishes. New o-rings can be had from your local hardware store if you can persuade them to go through their stocks. I have the measurements somewhere (courtesy Bryan Jones) and will post them if I can find them.

Check the Carb FAQ: http://forums.sohc4.net/index.php?topic=5410.0

A fuel filter will clog quickly unless you clean out the tank!
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Offline SteveD CB500F

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Re: HONDA 500/4 later carbs?
« Reply #5 on: April 21, 2009, 03:36:02 AM »
Forgot to say; if you go for eBay, make sure you buy carbs up to 1976 as the 77/78 carbs are completely different.

You can usually tell from the photo as the 77/78 have front-rear carb top screws (as opposed to side-by-side as yours are)
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Offline hymodyne

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Re: HONDA 500/4 later carbs?
« Reply #6 on: April 21, 2009, 04:57:53 AM »
i've got 550K carbs on my 500K...they're about to go back on a 550 engine though...we'll see how jetting (w/pods) goes...
hym
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