[King_Panther13]

I tried doing top speed again yesterday, this time no work computer on my luggage rack, and with my throttle cable adjusted. Valves I think were adjusted since the last time too.



The bike's been accelerating better since tightening the throttle cable...another one of those "can't believe I missed it" things. But top speed on my GPS still only showed 95 MPH

. In fact, I hit top speed shortly before redline in the fourth gear, then shifted to the fifth. This time it seemed like the RPM didn't even get up to 8000, but at that speed everything is vibrating so much it's hard to tell. I didn't try holding it there for too long because a few curves were coming up, and it'd be embarrassing to crash on the easy Florida curves.



So, let's see here....could a loose cam chain, or valves not seating properly possibly cause a slower top speed? Those are the two biggest things I'm soon to get into, but I don't want to be disappointed if they don't "fix" it. But as I said, I don't usually run that fast with this bike; that's not what I expect of it. I'm just seeing if it's capable, and to fix any issues that are preventing it from being capable so it can run at the best of its abilities.

 

[ChopperCharles]

For speed issues with the CX500's, first thing is to check your ignition. If you've got a faulty CDI or a weak stator, it's never going to make 105 indicated.



Next, check your clutch. If it's slipping, you'll never make top end either.



Replace your air filter, change your oil, new plugs, spark plug caps, valves, etc.



Make sure the bike is running 100%. If it can't pull 100+ indicated, there's something wrong with the bike. Every CX500 I (or my father) have owned has pulled my lard ass over the ton. Yours can too.



Charles.

 

[VtypeV4]

I'm not often cruel to my CX by caining but i did have to see if it would crack the ton at least once.

Mine seems happy to pull up to 100 mph and without any stability issues. If I want to go fast, I'll run the FJ out however, I did have to do it once! I was flat on the tank giving it the beans trying to out drag the Mrs on the Bandit. My CX seems to go reasonably well (for a CX at least) and if it had another (half) gear I think it'd have kept pulling past 110!



Great old bikes.

 

[Justen]

One thing I can add here. If you use the wrong oil, such as synethic oil. It can slip very bad. Jetting, exhaust messed up can also cap the rpms. Bad voltage side of stator, or weak spark at the plugs. Even plugs gapped totally way off. Can affect the cx engine. But my first guess would be wet clutch slip.

 

[Runaway1956]

I tried doing top speed again yesterday, this time no work computer on my luggage rack, and with my throttle cable adjusted. Valves I think were adjusted since the last time too.



The bike's been accelerating better since tightening the throttle cable...another one of those "can't believe I missed it" things. But top speed on my GPS still only showed 95 MPH

. In fact, I hit top speed shortly before redline in the fourth gear, then shifted to the fifth. This time it seemed like the RPM didn't even get up to 8000, but at that speed everything is vibrating so much it's hard to tell. I didn't try holding it there for too long because a few curves were coming up, and it'd be embarrassing to crash on the easy Florida curves.



So, let's see here....could a loose cam chain, or valves not seating properly possibly cause a slower top speed? Those are the two biggest things I'm soon to get into, but I don't want to be disappointed if they don't "fix" it. But as I said, I don't usually run that fast with this bike; that's not what I expect of it. I'm just seeing if it's capable, and to fix any issues that are preventing it from being capable so it can run at the best of its abilities.

If you're reaching 95 mph, and 8k RPM or better - you're near top end for these bikes. I think that I'd worry less about tuning the engine, and work on eliminating the vibrations and shakes first. I've reached 100 on two bikes this year, and tried on a third.



The Kawasaki went well over 100 (I cut it off at about 118 because of curves ahead) and ran smooth as silk.



My GL just reaches 100, give or take two or three mph, and only vibrates a little bit.



The Honda Shadow vibrates like crazy, and it's top speed seems to be about 85. Sorry, I don't WANT to do 100 on a machine that vibrates like that! The faster it goes, the worse the vibration gets.



Really - find the shakes and the vibrations, then test for speed. An issue I never see addressed, in relation to bikes, is wasted energy in those shakes and vibrations. A wheel bearing, for instance, that may be causing a very minor vibration, may be eating a horsepower or two. Multiply that by all the items on the bike that can contribute to headshake, etc, and you might be dumping 1/10 of your total horsepower into wasted energy in the form of vibrations.



Get the bike smoothed out, and you may well gain another 5, 10, or even 15 mph. If I am totally wrong, and you don't even gain 1 mph - well, at least you've got a smooth ride, and you can actually LOOK AT your guages!



Of course, that won't necessarily apply to certain V-twins that were engineered about the time Henry Ford was setting up shop.

 

[Sture]

Sorry, I haven´t gone back and checked all previous postings. But by just scrolling over this thread it seems like 8000 RPM is what you get - no more.



Are you sure about your tacho? 8000 is just close to 140 kph in my book with a 16" rear, as on yours. An 18-incher would do ~ 145.



I´ve had a couple of very unreliable tachos. One was all over the place over 7000.



Usually I rely more on my tacho than my speedo. I have 18-inchers only. 1K rpm is as close as you get to 18kph for those.



In a speed trap 90 kph speedo indicated would be > 80 actual for me. Tacho 5000 rpm is much closer to 90 kph. Of course it varies a little between my bikes, but as a general rule it would be OK.



Sture

 

[murrayf]

with the mikunis on my 500 it will pull past 110 on my gps



i wont take it past there as the front end needs some more work but it was still pulling strong



before you try the high speed runs make sure your gear is up to snuff and you check everything including tire pressure



things can go bad very quickly over 100

 

[DM2Sleepy]

Cell phone GPS are meant for vehicle navigation, not data gathering.



as far as going above 8000rpm? that's a good one!



lube up your tach(take off and put upside down. apply a few drop of oild to the port for the tach cable. I would suggest doing this several times hours apart. make sure its saturated.).



then figure out your tach to speed ratio(wheats my tach say at 50mph).



tach/speed=x



x*tach=speed.

 

[murrayf]

i use a garmin gps not cell phone

 

[DM2Sleepy]

i use a garmin gps not cell phone

I was replying to the first page, had not noticed the second page. My apologies.



FWIW I'm pretty sure(based on SIMPLE rpm/speed calcs) mine has reached about 103mph(about 166kmh) without topping out.

 

[baldgrimsbybiker]

Mine goes fast - very fast. More than the legal limit.

 

[Runaway1956]

Mine goes fast - very fast. More than the legal limit.

What is this "legal limit", of which you speak? My physics teacher forgot to mention it. Perhaps you refer to the speed of light?

 

[Interstater]

One thing I can add here. If you use the wrong oil, such as synethic oil. It can slip very bad.

I know this isn't an oil thread but the above statement might be a little misinformation and should be clarified. Synthetics or semi-sythetics are ok for the CX/GL and are used by a lot of riders here (inlcuding me for about 5 years now with no problems), just make sure the oil is not labeled "energy conserving" or "resource conserving" and, preferably, that it is rated JASO MA. The JASO label means it is approved for 4-stroke motorcycles and an MA friction range works with wet clutches. I just picked up a jug of Rotella T6 5w40 at Menards, it is labeled JASO MA.



Read this on where the JASO designation comes from... http://www.jalos.or.jp/onfile/pdf/4T_EV0604.pdf



With all of this said, regular dino oil is fine for our bikes too.

 

[VtypeV4]

What is this "legal limit", of which you speak? My physics teacher forgot to mention it. Perhaps you refer to the speed of light?

Whilst I don't think the CX approaches it, my FJ gets alot closer and my friends' Blackbird almost certainly does! The speed of light that is!

 

[purplecx500]

What lt1 said so eloquently........ firstly i i haven't exceeded the ton for many years...but in 1979 i took my dresser cx500d to an indicated 114 no problem (right

after its first service), smooth as could be.............the speedo was as they say in the mags of the era optimistic by 8 to 10 % so lets say 104

now i have a 1979 cx500c it is much quicker in the lower gears than the cx d...0 to 65 is far more important than to 80 to 100...... i doubt top end is any faster and

will probably never know. .......