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increasing top speed on 250cc

Discussion in 'Technical and Troubleshooting Torque' started by voyager, Oct 5, 2004.

  1. Well, with the majority of my technical difficulties either solved or close to it, I can now think about the next operational issue I've discovered.

    I feel the need....

    ...the need...

    ...to be less of a giant wind brake on my poor little XV250! :p

    Anyone got any ideas on how to get an extra 10kph out of it ? At the moment, even if I chose to ride on a major highway (eg: Western Highway), I would deem it to be dangerous since I can't hold a speed within 20kph of the limit.

    Yep - 90 is about the stable top for me. Whilst I never made claims about wanting to go too fast, keeping up with the traffic on the Princes Fwy would be nice, otherwise any sort of serious commuting MAY not be practical.
  2. 3 options...

    1. Invest in a windshield for the front of it,
    2. Address mechanical performance,
    3. Lose some weight :?: (No offence, don't even know if you need to)

    I've ridden a Virago (about '96 - '99 model) and it could easily hold me at 100-110 on the freeway, with 125 quite achievable. It didn't have any screen. If #3 isn't an issue, then has #2 been looked at?
  3. #3 - even if I lost 50kg, I'm still 6'5 and pretty broad. In a jacket on my cruiser, I'm a huge wind brake, literally! I didn't think my weight would be been as much of a factor as my general size.

    #2 - engine seems solid and strong. A 6th gear would be perfect, but she's only got 5...
  4. Did the bike max out at 90kmph or that is the speed at which you started to feel unstable? I assume it maxed out if you want another 10k. If you felt unstable that initially will be just a case of getting used to the bike moving around a bit in the wind. The other problem you've got is the Virago puts out around 21bhp. An Across for example puts out about 45bhp. Both figures at new of course so an older bike will be putting out less. I would suspect 90kmph with a bigger guy on it like yourself is pretty much what you might expect without seriously modifying the bike.
    You are right about the dangers of freeway traffic, I wouldn't be on a freeway on a bike doing 80-90k. You are much safer moving with the general speed which is up to 110 in light traffic and having something in reserve to make sure you aren't sitting in blind spots etc.

    What you might like to do is try a few other bikes when your confidence is up to see how comfortable they are at speed. Fit is obviously a problem and you will enjoy your riding more on a bike you are comfortable on.
  5. I can push it a little further (5kph), but in general 90 is about its top cruising speed with me on it. Its reasonably comfortable at that speed. Obviously I'm still gaining confidance, but I don't really have the option of getting it up much higher. At times on the Sunday ride I had the throttle maxed open and was only doing 90.

    I felt (now don't take this for gospel as I don't know for sure) like I was the cause due to wind resistance across my torso. Whether a screen will fix that remains to be seen (the wind doesn't bother me comfort-wise, although I'll fit one if it will make a difference to the top speed).

    I'd just really like to be able to run the freeway at a safe speed. Otherwise I could be exposing myself to unnessecary dangers.
  6. What was the terrain you only got 90 on? Bond runs out of legs going up some hills & I need to kick him down a gear!
  7. Fairly straight road, slight incline (but only slight, not like full-on hills).

    Maybe that was the trouble, but I didn't seem to need to go down a gear. Like I said, a 6th Gear would be perfect!
  8. How hard were you pushing it in the revs in each gear. Top gear will take a while to get up to speed. Top speed on this bike is quoted at around 135 so there should be some room for improvement above your 90kg regardless of size. Other Virago riders can probably give you some good advice here.
  9. I was figuring it HAD to at least pull a ton... I'll do some more testing (plenty of freeway I can test it on nearby) and see.

    Either way, any suggested improvements would be greatly appreciated.
  10. Just a thought - but if you can hook up with another more experienced rider (ideally one that has ridden a virago 250 before) perhaps let them take it out on the freeway and / or roads they may shed some light on the problems. They would be able to tell you if it was mechanical, if it is the windbreak (i.e. you), or if it is just normal and takes some getting used to the stability at higher speeds.
  11. Take it to a mechanic if it's top cruising speed you're after and ask about changing the sprockets.
  12. I'd be happy to do so - will have to see who I can find.
  13. My 2004 XVS topped out at 130kph (the week before I stacked it. I'm 6" 120kg, bike fitted with screen. I agree that a sixth gear would feel better, seems to be overreving at 80-90 kph but fine once at or over 100.
  14. as tanya said
    changing the sprocketrs to ones with more or less teeth will adjust yor speed and rpm at speed , but will effect it at the other end of the scale

    ie change it to cruise at lower revs and higher speed ie highway , will effect pick up and power starting off , visa-versa

    example for the across from one of the posts

    Standard sprockets: 6th = 9500-10000RPM @ 100km/h

    I've got a much smaller rear sprocket and my 6th = 7000RPM @ 100km/h
  15. Mark - this isn't the XVS, only the XV, and its a 1992 model (so not new either). I would have loved an XVS250 but just couldn't find one I could afford.

    Acceleration I don't care too much about. If I rev it higher it takes off pretty quick, but I'll trade that for some added top-end. Its a baby cruiser after all, not a track racer.

    Sounds like a plan actually - thinking more about it, there is plenty of bottom end in the lower gears for a fast take-off. I can easily afford to lose some of that for a better top speed.

    tanyathecheeky - I think I may be owing you a coffee/beer...
  16. in all your other gears, where is the most gutsy rev range? and where is it at when your hitting 90kph? if your at the meatiest range at 90, then changing the sprocket might mean a lower speed due to the motor having to work harder. if you're well above that meaty range, then a smaller rear or larger front will work wonders.

    its a piss easy job to change sprockets over, and they are as cheap as chips to buy. i got a new front less one tooth for the cat for $18 and i think a rear is just $10 more. global motorcycle wreckers in dandenong is where i got that from.
  17. Thankyou voyager :D

    but i think you might have to post it :)
    Good luck..
  18. I think that went RIGHT over my head....

    I'll try to get out on the highway again in the next few days and see if I can dredge up more info about the problem.
  19. Coffee comes freeze-dried...
  20. Just install a NOS!!! :LOL: