[ramoneslobotomy]

Hello Everyone,



I have been turning my 1979 cx500x into a cafe racer. I was able to get it together enough to take it out on the interstate and see how fast the thing would go. I was able to get up to 85 mph, but then would run out of steam. All the gears would top out with proper rpm, except 5th that just seemed to really struggle to wind out. I weigh 230 pounds, but I would think this little 500 should be able to run 100 mph. Let me know what you guys are running your top speed at. Conditions today were cold with some wind, about 45 degrees F.



Thanks in advance,



Dan

 

[Reg in Bristol]

85 should be easy for a CX

My less then perfect example with barn door windscreen will do 85 easily

enough so maybe your motor needs some attention?

You should be able to cruise at 70-80 with the bike feeling 'busy' but not strained

rpm should be about 7000 at 80.

As to the top speed. Well like MPG, thats subject to all sorts of variables and fantasy

 

[Ohm]

I can peg out the speedo in 4th on my GL, toss it into 5th and the whole thing starts to get light and floaty as it winds out to redline.

 

[Blindstitch]

Top speed is 104mph. Depending on the mods done you can get a hair more out of it but not much.

 

[tvpierce]

Top speed is 104mph. Depending on the mods done you can get a hair more out of it but not much.

+1



I've had mine to an indicated 106mph on a long straight of an empty 4 lane. I know the my speedo reads 5-10 mph high.

 

[Shep]

I've had 107 Mph on one of mine but that's on the speedo so will be incorrect.A well serviced CX/GL should be able to do a ton but I wouldn't recommend it for long periods with the old metal in these engines.



As Reg says they can sit at 70/80 all day long and be happy.I came back from a ride-out using Motorways/Interstates for around an hour and a half doing between 65 to 90 for,"Combat speed" and the bike/s have performed great alongside some very modern bigger bikes

My 10 penn'th

 

[Reg in Bristol]

I snapped a crank going too fast for too long on a bike which the day

before had won the 'best sounding engine' prize at a rally

Ouch! pride before the fall and all that.

I have never tested the top speed on this one, if I want to ride at triple figures

I use the beemer.

This one feels happy cruising at 6-7 thou and I tend keep it around there with occasional

breif forays up to a little over 8K just to blow the cobwebs out.

In this vid I reached about 90 ( 8000 at 1:24) quite easily.

Notice it 'shimmy' as I cross the white lines at 70-80, thats another reason I dont push it much.



[media]http://www.youtube.com/watch?v=WmTfePCHOPw[/media]

 

[tvpierce]

I dig the air freshener Reg!

 

[Crshndbrn]

Now when you say you got it together enough to take it out, does that mean you've made mods like open exhaust? Open air cleaners? Have the jets been changed? Carbs adjusted and vacuum balanced? These all could affect it

 

[richnct]

Cripes Reg! Your riding on the wrong side of the road! Then passing on the right! What's wrong with you guys? How do you manage that? Do your signal lights work opposite of ours too? No wonder gas costs so much over there.

 

[Cobram]

Cripes Reg! Your riding on the wrong side of the road! Then passing on the right! What's wrong with you guys? How do you manage that? Do your signal lights work opposite of ours too? No wonder gas costs so much over there.

Naw, it looks like someone put the film in backwards when they put it in the projector. Emulsion side down next time.



The CX will cruise at 100-105 with no problems, so there is something limiting your bike. Start with the simple stuff, fuel supply. Make sure the in tank screen is in place and not partially blocked. Check you lines, inside diameter especially, there are plenty of hoses out there which have identical OD's but small ID's (high pressure fuelish injection and hydraulic lines) etc.



Plug caps, remove resistors with solid stock.



Keep us posted on what/if you find anything to explain your lack of top speed.

 

[trev_h]

My 500 will easiliy go over an indicated 100mph but I guess these old clocks are wildy inaccurate. Whilst following Reg to a rally on his beemer on one stretch I had the 650 hard on the stop !! Dam near lost my air freshener

 

[marshallf3]

108 just to see what to what it could do . 70-80 is fine for me, even less depeding on traffic.

 

[edinlr]

In order to hit top speed on any bike it has to be running nearly perfect. Previous posts mentioned tuning and I will second that. Your bike sounds like it is running about 15 to 20 slow. I would start with a compression check, then valves, plugs, timing, and carbs. Boise is about 2700 foot altitude so you are losing some horsepower there, but not that much. You could have some jetting issues that are not allowing you to pull high rpm under load in 5th. Also, you're a big guy and you will really have to get snug on the bike to reach top speed. If you have a jacket flapping around, it is essentially a parachute, so tuck it all in. Next time out see what the max rpm is in 5th.

 

[tvpierce]

Also, you're a big guy and you will really have to get snug on the bike to reach top speed. If you have a jacket flapping around, it is essentially a parachute, so tuck it all in. Next time out see what the max rpm is in 5th.

Good point. I should mention that I'm 160 lbs, and I was in a full tuck when I hit 106 mph indicated. And I've clocked my bike with a GPS... so I know my actual was more like 98 mph -- and it's state of tune is not 100%.

 

[Ookie Wonderslug]

I haven't had this new engine very fast. I did get it to 9500 rpm in 5th once. Since my speedo stops at 85 I don't know how fast I went. Passing usually ends up at 85mph before I can lean back into my lane.

 

[kingston73]

Mine never goes over 85, at least according to the speedo. My original speedo indicated up to 105 or 110, I forget which, but my new, post 70's oil crisis speedo only has 80 plus a hash mark.

 

[Matt_the_Rat]

I've only taken mine up "to the Ton" a few times. They will do it, but they have to be right.

If you changed exhaust or air box from stock, then you have to rejet the carbs. A stock set up with loose valves, and unadjusted timing chain , old tires, weak gas will not run up to 100.

I don't know the state of tune on your ride, but with more work it will run up there. It sure is busy on one of these at 100+.....

 

[cdyoung1985]

Don't know my top speed, I peg the speedometer at 85 at around 7k-7500 rpms, and just the other day had it clear to 9800 or so, just under 10k on my CX500C, only mod I have it straight pipe exhaust, and haven't adjusted the jets to match, and carbs aren't balanced either

 

[edinlr]

I haven't had this new engine very fast. I did get it to 9500 rpm in 5th once. Since my speedo stops at 85 I don't know how fast I went. Passing usually ends up at 85mph before I can lean back into my lane.

A fairly close estimate of your top speed would be to see how many rpm you can pull and then check your speed at half the rpm. If you can hit 9000 and the speedo is obviously at 85 or in the blank, then see what your speed is at 4500- maybe 55mph. Double that and you have an "indicated" 110 at 9000rpm. Of course we have the error to allow for but that should at least give you a comparison to see if things are working or not.