: 2 stroke 500cc GP bikes



Teknic
04-13-2003, 08:07 PM
I was reading an article about how Hopkins and he mentioned how lucky he was to learn to ride a 2 stroke GP machine and how hard it was. I was wondering why is it so dificult to learn these bikes. First of I've never riding anything 2 stroke so I wouldnt have the slightest but what kind of differences can one expect...I thought they would be pretty much the same as riding a four.

:thumbup

RedDragoN
04-13-2003, 08:17 PM
I believe the power bands on a two stroke are super thin and way high up the rev range so you have to be all over the shifter.

factory_pilot
04-13-2003, 08:37 PM
i want you to imagine you're on your bike, and your riding down the track, and your going through a corner,

let off the brakes, get on the throttle to stabilize the bike, somewhere between apex to exit, you start to get on the throttle , and suddenly the hand of god (i'm not religious, just using a schwantian term) grabs your throttle and yanks it W.F.O.

Well, that's probably a very accurate description of what a full factory 2 stroke 500 would feel like. At a certain RPM, the engine comes on song, and slams you back against the seat stop.

It's a literal step up in the powerband.

And yeah, 2 strokes are very fun

gixxstar
04-13-2003, 09:13 PM
If they are anything like offroad race bikes......the only way to describe the power is explosive. They have almost no power whatsoever in the lowest ranges, then all of a sudden, the bike just takes off. There is very little compression braking in the engine when you let off too. I've always wanted to ride a sportbike with one of the newer two stroke engines in them.

arcrz
04-13-2003, 10:17 PM
I`ve got an RZ 500.Its a V-4 2 stroke,similar configuration to the YZR with 1/2 the power and 100 pounds more weight.The power band is pretty narrow and very explosive,I make all my power between 8000 and 11000 rpm.Its pretty docile and not too impressive under 7500 and has no bottom end at all.But at 7500 rpm when my power valves open up it hits redline right now if i`m hard on the throttle.Even when your not hard on it ,as soon as the power valves open it gets a bit squirly.On a Dyno it showed that it starts to make power at 8000 rpm (65 hp) and by 10500 it hit its peak(102).I`d give my left nut to ride a factory 500.Any test I`ve read,from even the most jaded moto journalist,they always walk away amazed at the performance level those things are at.Almost all the GP riders that have raced 2-strokes and are now on 4 strokes say how much easier it is to ride the Deisel.

They are totally different to ride then a four stroke.Whenever I get on a "deisel":D I have to make a concious effort for the first few minutes to remember that I dont have to rev the shit out of it to get going,they have torque, that I dont have to have the thing screaming all the time to get anywhere and that when entering a corner I dont have to stand on the brakes as hard cuz my motor will help me slow down too.It gives me a big grin every time I ride it.:rider

MikeMan
04-14-2003, 10:19 AM
I agree with arcrz, I have an RD and the power band is from 6-9500 and it pulls damn hard and those 3 1/2 thousand rpm come and go damn quick. One huge difference is the engine braking, let off the throttle on your 4 and it will brake pretty good without the brakes on, a 2-stroke is like just pulling in the clutch without the brakes on.

You can make more power with a 2 stroke than 4. My RD is a 350 with aftermarket pipes and it makes about 60hp, my ZX6 has about 90.

A couple last points, 2-strokes smell better, and sound better.

arcrz
04-14-2003, 01:00 PM
Thought this might interest you guys.Its a dyno graph comparison of a stock RZ and modified one.This particular modded bike is a monster.He has been clocked in the mid 180 mph range on a track.I love the burst of power from 7 to 10 on this thing.

arcrz
04-14-2003, 01:08 PM
This is a list of the mods:
Trued and welded cranks, friction gears removed Yamaha TSI counterbalancer mod (Driven off the rear crank instead od the front), ATR lightened flywheel (balenced by Leitner & Bush), Mikuni TMX28 flat slide carbs with K&N filters, Modified reed cages and Carbon Tech carbon reeds, Weisco Prolite Single ring pistons, Milled heads with re-contoured squish bands, Yamaha TSI Ported cylinders Plus a little, Cryo-stabilized cases, rotating and reciprocating components, Fully undercut transmission, Barnett clutch, BDK programmable black boxes for Ignition and YPVS, Indexed static Ignition advance 0-5 degrees, Jolly Moto GP style pipes and short alloy cans, Blueprinting and engine assembly by ATR - 139 dyno runs for tuning, SPA Tach/speedo, Daytona Digital water temp, ZX7RR radiator, 2001 R1 forks, Custom swingarm built from 2001 R1, 2000 R6, and RZV500 parts 3/4" longer than stock, ATR ride height adjuster, Attack Performance billet Triple clamps, Vortex Clipons, Marchesini M5 wheels 3.5 x 17 front 6.25 x 16.5 rear, Modified sprocket carrier, Sprocket Specialist rear sprockets, AFAM R1 front sprockets, 520 Chain, 17/41, 17/43, or 17,45 final drive, Street-n-comp Steering damper, Street-n-Comp fork clamp, custom billet rearsets (Wyn B. at CMPF) with CFM Motorsports (Eric Wood) pegs and levers, Daytona Damper Frame Clamp, Ohlins Rear shock with remote preload adjuster, Custom faring stays, 0.8 amp hour sealed gell cell battery, Motion Pro Quick Disconnect fuel lines, Fuel tank quick disconnect mounting pins, modified for tipover and positive venting with spin on filler cap, Nissin front master, Brembo rear master Speglier full floating brake conversion, Just to list a few.

This is the bike.

arcrz
04-14-2003, 01:09 PM
:)

SILVER_6R
04-14-2003, 01:40 PM
that bike is sweet!!!

my buddy just bought a new engine for his 1990 RGV-T 250. i cant wait for a chance to ride that baby. they dont call it the widowmaker for nothing!!

RedDragoN
04-14-2003, 02:24 PM
One word, sick!

Jumby
04-14-2003, 07:28 PM
I race with a friend that has 3 rg 500s, his fast 1 which just ran 123RW hp, his other 2 are both around 100hp @ the rear wheel. The problem with these bikes, is they handle like shit. With wider rims and the new stickyer tires it puts huge stess on the frame, it causes the frame to windup then unwind like a big spring. If you brace up the frame the flex moves to the next weekest spot, which is usualy the steering head. If it's posible to make that stiffer, you MAY have some hope of good handling. In the end the bike was never designed for that kind traction and power.If you enjoy trying to make a street bike in to your version of a GP bike go for it, it will be alot of fun. That RZ does look good.

rg500
04-14-2003, 07:38 PM
used to own a rg500 Walter Wolf replica. Between 6000 and 8000 the power doubled. for an old bike ('86) it used to do quite well. my buddies FJ1200 could not pull away from it.

James
04-15-2003, 10:50 AM
Put it this way. If my RZ isn't warmed up, the clutch drag will stall it.

They have no power below about 6 grand. Above that they will pull away from quite a few old bikes. Anything below an SS600 will be given a good run. They suck at quarter mile though, not enough low end torque.