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Author Topic: 1972 CB500 my top speed is limited  (Read 6107 times)

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jonathantaylor86

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1972 CB500 my top speed is limited
« on: March 04, 2009, 10:59:37 AM »
My brother just passed away and gave me his motorcycle. It needs a bit of work, but I want to get it in top shape so I can ride it without any concerns. The bike is a 1972 Honda CB500 which visually and mechanically looks and sounds good but it seems to top out at 65 or so. It hits 65 and thats it. I have never owned a bike so I dont know much but if anyone has any suggestions please let me know.

I'm sure there are many answers to this question but if you have one let me know cause i took it to a bike shop and they qouted a ridiculous price just to diagnos the problem.
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Offline PJ

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Re: 1972 CB500 my top speed is limited
« Reply #1 on: March 04, 2009, 11:11:30 AM »
Hi Johnathon, is your bike a two or four cylinder engine? I know they made 500s both ways not sure of the years.
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Offline bwaller

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Re: 1972 CB500 my top speed is limited
« Reply #2 on: March 04, 2009, 12:17:14 PM »
If it's a 72 then four cylinder it is, and it should surpass the 65mph mark easily.

You can download from this site a Honda service manual which will walk you through a tune-up procedure. When you've read up you can decide whether or not to change spark plugs, points & condensors. An engine oil & filter change for sure. Don't be afraid to ask for help, but it's something you can do yourself.

Sorry to hear about your brother.
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Offline TwoTired

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Re: 1972 CB500 my top speed is limited
« Reply #3 on: March 04, 2009, 12:29:38 PM »
Carefully check the head pipes for even heat.
65 is about the limit if only three are firing out of four.

Otherwise, go through a full tune up maintenance cycle before troubleshooting.

Cheers,
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Offline SteveD CB500F

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Re: 1972 CB500 my top speed is limited
« Reply #4 on: March 04, 2009, 12:51:58 PM »
There I was reading through posts #1 and #2 and thinking "I'll bet its only running on three cylinders"

Great minds obviously think alike (of course, we could both be wrong...  8))
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Offline Hush

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Re: 1972 CB500 my top speed is limited
« Reply #5 on: March 04, 2009, 01:33:52 PM »
Also pull your air filter out and see if it looks like Aunt Betty's duvet cover, my 650 has the same symptoms and I'm pretty sure its not getting enough air to the mixture, once these filters block up its sayonara.
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Offline bender01

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Re: 1972 CB500 my top speed is limited
« Reply #6 on: March 04, 2009, 07:49:23 PM »
Your carbs may need cleaning. I just seached tune up and such and didnt find a good link. Can someone else find a full tune up sequence? And post the link?  You are in the right place to search for answers. Search carb cleaning. Your Brother must have wanted the 500 to run well. Sorry for your loss. Welcome to SOHC.
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So, the strategy is to lie to people you are asking for help?

I think I'll be busy going for a ride.

Good luck!
Two Tired Quote !

Offline SteveD CB500F

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Re: 1972 CB500 my top speed is limited
« Reply #7 on: March 04, 2009, 11:47:52 PM »
You could do worse than start with the Carb FAQ
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jonathantaylor86

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Re: 1972 CB500 my top speed is limited
« Reply #8 on: March 07, 2009, 04:07:31 PM »
Twotired was right the cylinder second from the right is not working. when i checked the pipes it was only warm where the others would melt the skin off my hands. thanks
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Offline PJ

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Re: 1972 CB500 my top speed is limited
« Reply #9 on: March 07, 2009, 10:23:56 PM »
The plug cap, plug wire or plug for that cylinder is probably bad. I would try the plug cap first, try removing it from the plug then unscrew it from the wire. It has like a small screw inside it that holds it on the wire. try cutting just a few millimeters off the end of the wire and screwing the plug cap back on. Retest. If that doesn't help try switching the plug wires on cylinders 2 and 3. See if the cold cylinder follows the plug wire.
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Offline mystic_1

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Re: 1972 CB500 my top speed is limited
« Reply #10 on: March 07, 2009, 10:26:01 PM »
Quote from: jonathantaylor86 on March 07, 2009, 04:07:31 PM
Twotired was right

Get used to saying that ;)

Welcome to the site.  Keep us posted on your progress.

Got pics of the bike?  We like pics here :)

mystic_1
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Offline Spanner 1

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Re: 1972 CB500 my top speed is limited
« Reply #11 on: March 07, 2009, 10:41:23 PM »
The dreaded #3 not firing !!!
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If your sure it's an ignition problem; it's carbs....

fuzzybutt

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Re: 1972 CB500 my top speed is limited
« Reply #12 on: March 07, 2009, 11:17:20 PM »
try tapping the bottom of the float bowl on the carb on that cylinder with a screwdriver handle to see if the float may be sticking
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Offline manjisann

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Re: 1972 CB500 my top speed is limited
« Reply #13 on: March 08, 2009, 04:37:21 AM »
Quote
Twotired was right


Get used to saying that

Think of TT like the Yoda of bikes, short, green, kinda hard to understand, but he's always right!

Just Kidding TT  ;D

Seriously, welcome to the forum. If you know which end of the screwdriver to hit the nail with, this forum can help you fix anything on your bike!

Brandon
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1971 CB500 Frame 650 engine: Project

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jonathantaylor86

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Re: 1972 CB500 my top speed is limited
« Reply #14 on: March 09, 2009, 10:29:59 AM »
Thanks for your help everyone. I will try your suggestions to see if I can resolve the problem. I am a rookie when it comes to fixing bikes, but I want to make this a DIY project. Once I get it cleaned up will post some pics.
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