Top Speed
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1,574 Posts
Brand new, magazine reviews only got it to just above 100, I think the highest I saw in any review was 109.
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144 Posts
I've never had a bike with an accurate speedometer. They seem to all read fast. My current speedometer reads about 5 mph fast at 65 mph. I usually ride with a GPS and just use that speedometer. If you have the correct front tire the odometer of a gear driven speedometer can be very accurate. My odometer matches my GPS.
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144 Posts
I've never had a bike with an accurate speedometer. They seem to all read fast. My current speedometer reads about 5 mph fast at 65 mph. I usually ride with a GPS and just use that speedometer. If you have the correct front tire the odometer of a gear driven speedometer can be very accurate. My odometer matches my GPS.
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1,157 Posts
Apparently ALL motorcycle speedos are not accurate.
Never had one match my GPS, all showed faster by about 5-8 kph.
Just yesterday we were having this conversation at the local coffee shop, and one guy piped up
it was because of a liability issue on the mfgs. part. Did not get a chance to further the reasoning
of this because, a 1948 flathead Harley Davidson with sidecar pulled into the lot and the conversation
changed instantly. WOW what a showbike. Never made it back to the speedo topic.
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Never had one match my GPS, all showed faster by about 5-8 kph.
Just yesterday we were having this conversation at the local coffee shop, and one guy piped up
it was because of a liability issue on the mfgs. part. Did not get a chance to further the reasoning
of this because, a 1948 flathead Harley Davidson with sidecar pulled into the lot and the conversation
changed instantly. WOW what a showbike. Never made it back to the speedo topic.
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13,451 Posts
All speedometers are over and under at certain speeds. As for mechanical speedometers being correct well what's mechanical?
Sure a gear spins at the wheel and connects to a cable. But when it goes into the back of the speedometer that cable turns a turns a gear and a magnet. The gear goes to the odometer/tripmeter and the magnet pulls the needle into the right position but without resistance it is off. So to do that there is a spring inside. Over time springs lose tension and inaccuracy happens. Now we have another fail rate.
I can tell you that I test all my speedometers with a drill and set them to 64mph which is the speed the drill will turn them. Anything above or below is off.
I have one that's dead on at 64mph but at 30mph it thinks it's going 20. And that's not good.
Sure a gear spins at the wheel and connects to a cable. But when it goes into the back of the speedometer that cable turns a turns a gear and a magnet. The gear goes to the odometer/tripmeter and the magnet pulls the needle into the right position but without resistance it is off. So to do that there is a spring inside. Over time springs lose tension and inaccuracy happens. Now we have another fail rate.
I can tell you that I test all my speedometers with a drill and set them to 64mph which is the speed the drill will turn them. Anything above or below is off.
I have one that's dead on at 64mph but at 30mph it thinks it's going 20. And that's not good.
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605 Posts
Down hill, with a tail wind, and only looking at a gps, I got my 'nearly new' GL500 engine to pump her up to 113 mph.
keep in mind, any additional equipment onboard will limit actual top speed (ie windshilds/saddlebags/trunks,
and large sized middle aged males) I seem to remember, back when the bike really was new, in 1982,
and I was still only about 116 lbs. soaking wet, I broke 120 on the speedo - best you could do
back then, as there weren't any gps devices.
As for why... I believe the 5-10 m/h over is built in to avoid Honda's liability of speeding tickets. If you ride the
limit, and the cop has his radar accurate - you are actually doing less than the speed limit, and will NOT
be receiving a ticket.
keep in mind, any additional equipment onboard will limit actual top speed (ie windshilds/saddlebags/trunks,
and large sized middle aged males) I seem to remember, back when the bike really was new, in 1982,
and I was still only about 116 lbs. soaking wet, I broke 120 on the speedo - best you could do
back then, as there weren't any gps devices.
As for why... I believe the 5-10 m/h over is built in to avoid Honda's liability of speeding tickets. If you ride the
limit, and the cop has his radar accurate - you are actually doing less than the speed limit, and will NOT
be receiving a ticket.
The original owner of my CX got pulled doing 115 mph when it was fairly new. He had it just below the redline. When the trooper asked what he was doing he said "riding fast." Luckily for him he knew the guy, especially considering that was in the 55 days.
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274 Posts
FYI, one of the fellows in our group at Bonneville ran a stock appearing GL500 in Production Pushrod class. This bike has a 650 primary drive, mated to a 500 trans, 12.3:1 CP pistons, Webcam grind, GL650 valves, and Kemph ported heads. It also has the headers split and the inner tubing removed, then rewelded, plus a set of GL650 carbs. Density altitude on our time slips showed around 6000-7000 FT, and the rider weighs about 285. The bike would pull 11,000 RPM in the lower gears, but couldn't pull 5th gear.
The bike finally went 97mph on the salt....pretty good for the air density and rider weight! It is seriously hampered, for top speed, by the long intake and exhaust tuned lengths....it just WON'T come "on the cam" like my other engines do. We will try the bike with my carbs/manifolds and my exhaust lengths to see what happens at El Mirage (pretty similar air density, compared to Bonneville). I'll let you know if it works better.
Regards, JimL
The bike finally went 97mph on the salt....pretty good for the air density and rider weight! It is seriously hampered, for top speed, by the long intake and exhaust tuned lengths....it just WON'T come "on the cam" like my other engines do. We will try the bike with my carbs/manifolds and my exhaust lengths to see what happens at El Mirage (pretty similar air density, compared to Bonneville). I'll let you know if it works better.
Regards, JimL
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1,574 Posts
I'd be really interested to know how the magazines at the time measured the speed, as they all universally wrote that the CX topped out in 5th at 105 to 109. I have one article that says the cx custom made it to 106 in 1/2 mile. These articles were all for the 500's, I don't remember what the 650's top speeds were but I know they were about 2 seconds quicker to any speed.
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144 Posts
A 1983 Cycle Giude article I found on-line at: http://www.motorcyclespecs.co.za/model/Honda/honda_gl650_83.htm gives the GL650 a calculated top speed of 120MPH. It's clear they came up with their top speed by using the rear tire diameter, gear ratio and maximum allowable engine RPM.
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