High speed questions.

[shinyribs]

First,how fast can these bikes go? I know that is probably a loaded question.I was talking to the guy at the bike shop where I get parts. he asked me how the bike was doing and I told him how it tops out at 135 mph.He said that speed was impossible and that when these bikes were new they would rarely go past 105-110 mph. I told him I can do 120mph in only 2nd gear right at the 8500 redline.He said my speedo must be way fast.  Any thoughts?

Second,occasionally my front end will wobble at speed.Only at 120+ according to my speedo which may be off? It is not severe,I can hold the bars to overcome it,but you can still feel it trying to shake in your hands.Doesn't always do it.Maybe I'm hitting a bump that is causing it? Should I get a stabilizer?

Third,how could these speedos be off? Seems to me that with a factory sized front tire that it would have to read correct.Could it be the fault of the speedo itself?

Any and all ideas,please!

[TOOLS1]

Even if your speedometer was off by 10%, you would still be going 120 MPH. I do believe these bikes are capable of 135 MPH. They were advertised to go 125 MPH.
TOOLS

[shinyribs]

Dad told me he never could get any of his to hit the 150 mark,but said all of his would hit 135-140.I dunno.

[Dw07u]

personally I have never pushed my bike that fast, only did about 108mph... but it wasn like it was out of juice just yet, so i'm sure at least 125mph would be realistic yeah, and if your bike is running 100% then why not more?

[shinyribs]

I was reading your post about km/h and was wonder what that equates to mph...but was too lazy to go look at the speedo in my truck. What gear were you in and what rpm?

[Dw07u]

Mine also wobbles! scary as hel! I opened a topic about it a couple months ago, the guys said it might be the bearings, but no play on the steering, so the culprit is probably my old tire... which I have yet to replaced, will replace it either this month or the next... money is tight....

[Dw07u]

lets see, at that speed i was in 5th, cruising at about 6000 to 7000rpm... was too busy keeping myself and the bike stable as it was starting to wobble pretty bad...

[shinyribs]

Tire.Good point.Mine front tire rump-rump-rumps at 35 mph,but goes away by 40.Might check that out.Good call man

[cdaiscool]

I really, really doubt you were doing 120 mph in 2nd gear. I'd put money down on that. There isn't a trans commercially available that'll do that - the gearing would be so tall, it would take several minutes to start actually getting into your power band.

It may very well have been 120 kph though. 120 kph = 74.5645431 mph. So I'm guessing that you're both reading fairly high, and read it in kph.

If you have a smartphone and can ride one-handed, use a program called Trapster to track your speed. It won't track it on a history basis, but I've found it's near-instantaneous and perfect accuracy for actual speed. So you can at least find out how off it is at relative speeds. Speed is judged by the front wheel, and is irrelevant of the tachometer. So you can do a lower RPM at, say, 70 mph and find out how far it's off.

[Dw07u]

I must agree. Second gear at 120mph seems a bit.... Unreal... I just dont like redlining... Even my bike hates it... So I have to build up speed slowly.... I think my electrical issues are also contributing to my bike not loving the redline....

On another note... Do you really wanna go faster than 110mph on these bikes?

I mean
... No fairing, and the really high rpm.... I don't think its all that,great... At least not for sustained periods....
On 29 Mar 2012 07:29, "cdaiscool [via Honda CB750&apos;S]" <[hidden email]> wrote:
>
> I really, really doubt you were doing 120 mph in 2nd gear. I'd put money down on that. There isn't a trans commercially available that'll do that - the gearing would be so tall, it would take several minutes to start actually getting into your power band.
>
> It may very well have been 120 kph though. 120 kph = 74.5645431 mph. So I'm guessing that you're both reading fairly high, and read it in kph.
>
> If you have a smartphone and can ride one-handed, use a program called Trapster to track your speed. It won't track it on a history basis, but I've found it's near-instantaneous and perfect accuracy for actual speed. So you can at least find out how off it is at relative speeds. Speed is judged by the front wheel, and is irrelevant of the tachometer. So you can do a lower RPM at, say, 70 mph and find out how far it's off.
>
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[shinyribs]

Hmm.Looks like I need to mount my camera and do a little 2nd gear filming

Didnt know about Trapster.Have to check that out

Do I really want to go over 110...you betcha. Hey,why not?

[Dw07u]

Lol... It's not that we don't believed you... Just seems unlikely... I know my bike would not do that, not even close. Lol

On 29 Mar 2012 07:45, "shinyribs [via Honda CB750&apos;S]" <[hidden email]> wrote:

Hmm.Looks like I need to mount my camera and do a little 2nd gear filming

Montvale,Virginia
DUE TO RECENT ECONOMIC CONDITIONS, AND THE RISING COST OF ELECTRICITY, GAS AND OIL, THE LIGHT AT THE END OF THE TUNNEL HAS BEEN TURNED OFF.
Remember:Computers are fun...but you can't download a finished bike.   Get to work!
Common sense is not all that common
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[rrgunslinger]

With the wobble you are talking about I would not try it again until you figure that out.  Also if you are running tube tires I would think twice before going that fast.  Good luck and keep us informed.

[Dw07u]

I'm not using tube tires... the rubber is just really old... so the tire does not have a consistent compound all the way round... will get it replaced and let you guys know if the problem is gone

[LukeM]

Math wizard time:
1 mile = 1.6 km  or
1 km = .62 miles

This is close enough to the fraction 5/8 to convert Kilometers/kph to Miles/mph.  Use 8/5 to go from Miles to Kilometers.

30 mph ~= 48 kph
50 mph ~= 80 kph
62.5 mph ~= 100 kph
70 mph ~= 112.5 kph
125 mph ~= 200 kph
17500 mph (orbital velocity) ~= 28000 kph

I'm surprised seizetheday didn't chime in here.  He's from the Great White North.
Luke M

[sgtslag]

My DOHC bike has been rated at a maximum of 124 MPH (found it listed on BikeZ.com), but my clock is known to be 9 over, at 55 on the clock (actual speed, as per GPS unit, was 46 MPH) -- I've only had mine up to 95 on the clock (likely the low 80's in reality), and that was plenty fast for me...  If you have a GPS, that will tell you your actual speed, as well.  It is dead accurate, however it is not instantaneous, so you will need to maintain a given speed for 30 seconds, roughly.

Remember, pavement is like course sandpaper.  Denim will burn through, to your very soft flesh, in less than 0.5 seconds, at 60 MPH (found a study a few years ago, where the fellow did some real-world testing of different materials, dragging them with some weight on top of them, measuring how long they lasted before burning through...).  At 120 MPH, it will likely burn through in less than 0.25 seconds...  Leather is the best for abrasion duration -- it lasts longer than anything, but it won't last forever.

Any wobbling at high speeds, is v-e-r-y dangerous...  Make certain your have good tires!  Cheers!

[Half-Caf]

Dw07u wrote

Lol... It's not that we don't believed you... Just seems unlikely...

Speak for yourself -I don't believe a thing he says...

[Re-run]

First off, these engines would fly apart at that speed in 2nd. In 3rd on my bike, at 70 in third gear, I start to get close to the red. So, I would bet something isn't reading quite right. Top speed however is in the neighborhood of 125. I know it is well over 100, I did it last summer. I was testing my head gaskets before doing my 500 mile run. 150 would not be possible on these bikes without a lot of engine work to increase power to overcome air resistance. Some rickman fairing style work would probably help though.

The speedos were never 100% accurate, average deviation is about 8% or so I think. But it can be anywhere from 5-10 miles off but usually closer to the middle.

As for the shake, you have a number of causes. Your tire could be cupped or otherwise damaged, even if you can see it. If it is out of round a bit or out of balance, you can have issues.
Your rim could be out of round, you need a dial gauge to check this but it would be a good idea, especially if you have spokes.
head bearings could be bad even if they do not feel like it. A quick test would be to sit the bike on the center stand and put weight on the back to raise the front tire. Slowly rotate the bars back and forth and feel for any notching. You should also be able to set the bars just off of center on either side and they should turn that direction on their own with very little pressure. If not, new tapered bearings are in order.

Some new fork oil might be in order too. If the levels are of from each other, dampening can be affected.

And finally, the road you were on, did it have rain grooves cut into it or wheel tracks? Your bike might be fine and those damn things can cause wobbles.
A cheap stabilizer is not a bad idea though but check and correct any issues first.

[Scrappyike]

To convert kph to mph, just multiply kph by 6 and then drop the last digit.  

100kph x 6 = 600 which then equals to 60mph
120kph x 6 = 720 which then equals to 72mph
and so on.  

I lived in Europe and this is how I had to translated the mileage having brought back a German Spec car.  

[shinyribs]

Half-Caf wrote

Dw07u wrote

Lol... It's not that we don't believed you... Just seems unlikely...

Speak for yourself -I don't believe a thing he says...

LOL. Sorry guys.That wasnt what I meant. I meant,maybe my speedo is all jacked up and I'll do some testing to see.After thinking about it, my speedo drive is off another bike and maybe I am way off. With so many people who have experience with these bikes saying "no way" then chances are I do have an issue.

Rerun,I will check my rim.Thats a good idea.Since the wobble comes and goes it may be the road,not the bike.Lets hope so at least.I still would like to look into a steering stabilizer. Hmm,this would be a good time for Voxonda to pop in.