Page 3 of 3 FirstFirst 123
Results 21 to 30 of 30

Thread: Whats 300EX Top Speed?

  1. #21
    Join Date
    Aug 2005
    Location
    PA
    Posts
    1,168
    Originally posted by bwamos
    (Max RPM) * (1/ primary reduction) * (1/ 5th gear ratio) * (front sprocket/rear sprocket) * (tire circumference in inches) * (60 minutes/1hour) * (1ft/12in) * (1mile/5280ft) = top speed limited by max rpms.

    Using completely fictional numbers for rpm & primary/5th gear ratios. (I don't have rev limit or trans mission ratios in front of me)

    (7600rpm) * (1/ 3.00) * (1/ 1.00) * (13/38) * (22*3.14) * (60min/1hr) * (1ft/12in) * (1mile/5280ft) = 56.69mph

    Above is bogus as those aren't correct numbers. It's just how I would calculate theoretical top speed.
    alright I'm following so far...after reading it 20 or 30 times, the only thing I'm lost on is the primary reduction. What's that? Also which numbers aren't the correct ones. Sorry for bothering you with these questions...just curios
    Thank you for reading my post.

  2. #22
    Join Date
    Apr 2005
    Location
    KC, Missouri
    Posts
    5,225
    Max RPM, Primary reduction, and 5th gear were pulled out of thin air.

    Primary reduction is the gear reduction going from the crankshaft to the transmission cartridge. Then you have the Tranny gear reduction to the countershaft. Then the last reduction is the sprockets on the chain drive.

    The primary reduction is a fixed value.
    Tranny reduction varies with 1st-5th and Reverse.
    The chain drive reduction is fixed unless you swap out sprockets.

    Sometimes you'll hear the term "final drive ratio". That can be one of 2 things. It's usually the primary reduction & transmission gear reductions combined at each gear giving you the total reduction from the crankshaft through the countershaft.

    Sometimes people include the chain drive reduction. But since that's an "adjustment point", I prefer to leave that out of the equation.
    Brandon -O||||O-
    1998 Honda TRX300EX (330)

  3. #23
    Join Date
    Aug 2005
    Location
    PA
    Posts
    1,168
    Thanks
    Thank you for reading my post.

  4. #24
    Join Date
    Nov 2005
    Posts
    413
    52 mph
    2005 450R w/ mods

  5. #25
    Join Date
    Apr 2005
    Location
    KC, Missouri
    Posts
    5,225
    Originally posted by Seano300ex
    a while ago in dirtwheels....
    I while ago (about 7 years ago) I read that if you add a 38mm Mikuni FS Carb (it had no accelerator pump) to a 300ex it would make it run like a 250R.

    They tend to pull "facts" out of their butts.. lol.

    What they should have said was. If you don't feather the clutch it would dog real bad because it doesnt have an accelrator pump, and the fuel tube is on the opposite side of the carb so with the funky routing if you hit a hill right you'd starve the motor. The throttle cable provided also hits the fuel tank so you had to order a custom cable or tilt the carburetor about 10degrees to the right(exasperating the starvation problem). The pull on the included twist throttle wouldn't open/close the carb fully. Other than that it was great. I put the stocker back on a month later.. lol.

    I wonder if they actually test anything. LOL. If they do it's not objective, or correct.. lol.
    Brandon -O||||O-
    1998 Honda TRX300EX (330)

  6. #26
    Join Date
    Jun 2007
    Location
    Greene Pa (sw)
    Posts
    87
    hey guys i used to race a 2002 300ex nice ride to play and learn i had a 11.5:1 high comp wiseco piston, stage 2 cam, stage 2 jets, hardened rockers ,ported and polished,k&n filter no lid with a 14 tooth front and a 36 rear sprocket and still had allkinds of lowend with 20" rear tires . and could keep up with a 400ex with a pipe and a stock 400ex runs 65 it was all my bike would do in the rev.

    a stock 300 runs around 55 give or take a few
    07 450er
    kick start kit
    fox float evols
    walsh +2 steering stem
    hmf red can
    dyno jet jets
    k&n filter with precharger
    pro-armor fat peg nerfs
    pro-armor belly skid
    gt thunder sproket guard
    Dg V pro front bumper
    fasst flexx bars
    cycra pro bend handguards
    (brp mount 4 flexx bars)
    gibson Steering Stabilizer
    msr clutch perch
    clark oversized gas tank
    boyeson quick shot 2
    renthal sprockets
    quad tech seat cover
    maxxis razr II's all the way around

    08 KTM 450 xc
    Fasst Flexx bars
    Boyeson quick shot 2
    Dasa pipe
    PRM-atv bumper / grab bar / skid
    cycra pro bend handguards
    Honda throttle
    ITP beadlocks
    precision steering damper
    and sum polishing

    www.myspace.com/gnccguy

  7. #27
    Join Date
    Nov 2003
    Location
    upstate NY
    Posts
    497
    my 300 w/350x motor and 14/36 gearing ran 73.8 with gps and had a bit more to go, probably 74-75.

    bwamos, my buddy had one of those mikuni carb 'kits', it was a joke. wouldn't fit under the tank, had to run a twist, and didn't run much better than stock. thank god for the 400ex and FCR. also, what gearing were you running to get 74 out of yours?
    don't buy from Paul Corbin aka TampaBoy813

    01 492ex

  8. #28
    Join Date
    Apr 2005
    Location
    KC, Missouri
    Posts
    5,225
    14/36 but that's pegged out on the higher limiter on smooth hard pack w/ a slight downhill incline w/ my lighter stock 22's.. lol. There's only 2 spots smooth enough and long enough that I can do that.. lol. (legaly at least, I don't ride on roads).

    It has a hard time hitting the limit on anything else with that gearing.. lol. That's pretty much just to see what it could do. I normally run 13/36 gearing which tops me out in the mid to upper 60's.

    I bet if you put the stock 2-ply 22's on your 350x you could get quite a bit more.. lol. A lot less rotating mass.. lol. (yes I cheated). But my buddies and I had a bet. They didn't think a 300ex couldn't break the 70mph mark.. lol. So I optimized.. lol. The banshee still out ran me though.. LOL.
    Brandon -O||||O-
    1998 Honda TRX300EX (330)

  9. #29
    Join Date
    Nov 2003
    Location
    upstate NY
    Posts
    497
    22's, ok, that makes sense. i had 20's. yea either way thats moving, the front fenders turn into wings at those speeds
    don't buy from Paul Corbin aka TampaBoy813

    01 492ex

  10. #30
    Join Date
    Feb 2005
    Location
    ohio
    Posts
    2,333
    Yeah it COULD be possible but i cant imagine a 300ex doing 76mph with 18in tires.Im running 14/34 gearing and i can blow it up in 5th if i wanted and i dont have a rev limiter.I cant say the exact speed though but with the bore kit and fcr carb etc,it maxes out pretty quick.the 18s arent the tire of choice for high speed runs,it works for the track though.
    426ex,lt250r banshee and kfx700 v force,yz250 mx bike

Page 3 of 3 FirstFirst 123

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •