Oh Lord (CB500) - The Leaky Bitch (p. 31)

Re: Oh Lord (CB500) - Oil Vapor? (Pg. 28)

Hey guys,
I'm wondering; where abouts should a 1972 CB500 thats running smoothly top out? I've got a really big bore exhaust and velocity stacks on this bike. The spedometer indicated I was topped out somewhere in the 60 MPH area. Is this normal? It didn't feel like it was out of power yet, but like I just ran out of throttle.
 
Re: Oh Lord (CB500) - Question about top speed... (Pg. 29)

A big bore exhaust? What is that? Stacks? Been rejetted?

Anyway, I've seen some 500's flat out at just above 105. That's well maintained, and jetted correctly.
I've seen em much faster, but those are built.
 
Re: Oh Lord (CB500) - Oil Vapor? (Pg. 28)

03rangerxlt said:
Hey guys,
I'm wondering; where abouts should a 1972 CB500 thats running smoothly top out? I've got a really big bore exhaust and velocity stacks on this bike. The spedometer indicated I was topped out somewhere in the 60 MPH area. Is this normal? It didn't feel like it was out of power yet, but like I just ran out of throttle.
Click to expand...

Ha, 60 indicates big problems. You should easily see 90-100
My 400f will top 105.
 
Re: Oh Lord (CB500) - Question about top speed... (Pg. 29)

mlinder said:
A big bore exhaust? What is that? Stacks? Been rejetted?

Anyway, I've seen some 500's flat out at just above 105. That's well maintained, and jetted correctly.
I've seen em much faster, but those are built.
Click to expand...

Its got a big diameter Yoshimora replica exhaust on it with very little baffle to it. Its running velocity stacks with screens on the ends, and its jetted as correctly as you can get in these conditions. There is a little low end stumble, but when you get cranking she responds very quickly. :)
 
Re: Oh Lord (CB500) - Question about top speed... (Pg. 29)

"and its jetted as correctly as you can get in these conditions"

What does this mean? There is correctly, or incorrectly.
Who jetted it? What are your jet sizes? What do your plugs look like?

You have stacks and an open, aftermarket exhaust. That requires rejetting. Has it been done correctly?

What else has been done to the bike?
 
Re: Oh Lord (CB500) - Question about top speed... (Pg. 29)

mlinder said:
"and its jetted as correctly as you can get in these conditions"

What does this mean? There is correctly, or incorrectly.
Who jetted it? What are your jet sizes? What do your plugs look like?

You have stacks and an open, aftermarket exhaust. That requires rejetting. Has it been done correctly?

What else has been done to the bike?
Click to expand...

115 Main jets, 42 pilot jets
NGK D8ES or D7ES plugs (probobly went just hotter than stock)
No other mods

As for, "and its jetted as correctly as you can get in these conditions," I mean, without the air box and with a very free flowing exhaust...

There is that low end stumble but once you get past it (ussually with a little bit of throttle) this thing accelerates with a quickness. Oh yeah, it has the stock sprokets on it.

Keep in mind, while I built my own bike from parts, I had no clue as to what I was doing. i still don't. :)
 
Re: Oh Lord (CB500) - Question about top speed... (Pg. 29)

John, What RPM are you at at 60? I ask because if it is excelerating hard and will rev to redline in 5th your speedo may be screwed up a bit. I put the speedo from my CX on my GL when the odometer shit the bed on the original GL one. I rode to work the first time and it would not go past 50 mph, but the bike was in 5th at 5K which is normally 85 mph, for 3-4 days the speedo would go to 50 mph, never higher, then it slowly would got to 60 mph, same rpm, so I realized the spring inside must be stuck, so I took the bike on the freeway and opened it up to what would be 100+ MPH and then back off, did it again, backed off, did it again and each time I got a new top speed until it was reading the 120 MPH top speed the bike can do, been good since. just needed a good exercising, now being a police officer I knkw you wouldn't take your bike out and do that ;D
 
Re: Oh Lord (CB500) - Question about top speed... (Pg. 29)

Yes, something is not allowing it to run right. With stock sprocket it should at least maintain highway speeds with ease, you can't even get there on a 65 mph highway.
Are your throttle plates opening all the way? I'd peek down the stacks and see... May be something as simple as a pull cable adjustment.
 
Re: Oh Lord (CB500) - Question about top speed... (Pg. 29)

Drop down to 102.5 or 105 mains.

Sometimes stacks create a stronger venturi than you might think, and suck in a bit more fuel than you'd think.

Again, what do the plugs look like?

Are you sure you are running on all 4?

As maritime asked also, what RPM are you at at top speed in 5th?
 
Re: Oh Lord (CB500) - Question about top speed... (Pg. 29)

That CB500 is not right. My CB360 is faster......

You have a problem somewhere......Are you sure your throttle is even opening. they were fast bikes in their time, and faster than the twins....
 
Re: Oh Lord (CB500) - Question about top speed... (Pg. 29)

Yeah, my 1971 CB500 is bot even at half throttle at 65. I'm running pods and a 4 to 1 exhaust with stock jetting. I'd start from the beginning and check tappets, point, timing, cam tension, then look at your carbs.
 
Oh Lord (CB500) - Question about top speed... (Pg. 29)

I know I raise hackles, but pods and 4 cylinders are near impossible to tune without a whole lot of work. The inside carbs see different air temps and pressures compared to the outside carbs.

A common plenum is needed to tune a 4 cyl easily.




Sent from planet Earth using mysterious electronic devices and Tapatalk
 
Re: Oh Lord (CB500) - Question about top speed... (Pg. 29)

How much free play in your clutch lever, mate?
 
Re: Oh Lord (CB500) - Question about top speed... (Pg. 29)

Thanks guys for all of the suggestions of things to look at.

mydlyfkryzis: You aren't raising any hackles here! When I originally bought the bike, my plans were to run velocity stacks, and it turned out the bike didn't have an airbox. Later, while researching my little project, I learned this isn't the optimal setup for a CB streetbike. But, I decided to make what I had work as best I could.

The clutch is VERY stiff, even after being adjusted and having the adjuster lubed up pretty good. If I can figure it out, I will be turned into a hydraulic clutch sometime in the next couple years. :)

I am thinking about ditching the velocity stacks and going over to pods.

I am a little worried about an "uh-oh" I made to one fo the carbs. I tightened the the velocity stack set screw just a touch to much and pinched the opening a little. I need to investigate whether or not this is keeping it from opening up all the way. Looks like I have some stuff to start looking at.

Oh yeah, and I may have to hit the ton at least once on this thing, you know. ;)
 
Re: Oh Lord (CB500) - Question about top speed... (Pg. 29)

Are you firing on all 4? What do the plugs look like?
 
Re: Oh Lord (CB500) - Question about top speed... (Pg. 29)

I'm pretty sure its on all 4. The plugs were just changed out. The bike was running very rich before being rejeted (had 120s in it if I remember correctly) and the plugs were looking fouled.
 
Re: Oh Lord (CB500) - Question about top speed... (Pg. 29)

Start bike up. Let run. Touch each header with back of your hand. Do they all burn you?

Have you looked at the plugs since you went to 115's?

If not, do it now.
 
Re: Oh Lord (CB500) - Question about top speed... (Pg. 29)

My suggestion is that you check your clutch free-play. If there is no free-play, your clutch plates are not fully engaging :)
 
Re: Oh Lord (CB500) - Question about top speed... (Pg. 29)

mlinder said:
Start bike up. Let run. Touch each header with back of your hand. Do they all burn you?
Click to expand...
If you don't wait, you can feel each pipe warm up without burning yourself... Or spray water on it with a squirt bottle once it is warmed up.


03rangerxlt said:
...I am a little worried about an "uh-oh" I made to one fo the carbs. I tightened the the velocity stack set screw just a touch to much and pinched the opening a little. I need to investigate whether or not this is keeping it from opening up all the way....
Click to expand...

Yes, refer to my previous post.
 
Re: Oh Lord (CB500) - Question about top speed... (Pg. 29)

or buy a $35 infrared non contact thermometer from Harbor freight and measure the temperature. Even if they aren't accurate, they are good for comparing the pipes to each other....
 
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