2 stroke wonders

[dirt devil]

hey fellas sorta new to the whole mini bike scene in australia but i really wana get into it, just wondering if there was any types of good two stroke pit bikes i should look into cause ive only ever seen all the four stroke models Bring back the two stroke!!! cheers

 

[I_THUMP]

if u want 2 stroke then u need to look at Jap or Euro bikes

 

[red_demon24]

buy a kx65 or rm65 and do that up eg:usd forks high rise bars and stuff and it would look good i reckon heaps of fun aswell them little bikes go pretty quik
or maybe even a kx80 rm80 yz80 cr80

 

[Gureno]

KX80 mate.

look good when thier biult up right.

and go even better, my 80 destroys any pitbike i have ever owned.

but reliability is a problem so you have to be pretty mechanically minded with those things cause they will fail if you dont manage them correctly.

but no i have never seen a PITBIKE that has a 2stroke motor, i just think thiers not much market for 2 stroke motors in pitbikes, considering lifan and ducar do the majority of cheap sales thier motors are all 4 strokes (that i know of).

might have to just settle for what the market is offering

 

[I_THUMP]

Honda over Kawasaki everytime

 

[Sidney]

nah I gotta admit kawasakis are better (only the 2 bangers)

 

[I_THUMP]

What do u base that on sidney? Can u back up your comment?

 

[Sidney]

kawasaki are just better at making 2 bangers and honda are just better at making 4 bangers

 

[I_THUMP]

Well what facts do u base that on?

 

[Sidney]

Dude, kawasaki are simply better at making 2 stroke bikes, they are just engineered better. Honda don't even make 2 strokes anymore.

 

[I_THUMP]

Ive heard someone comment b4 to u that u should keep ur mouth shut about technical issues. Maybe this is one of them times lol

 

[Sidney]

kawasaki is just better at making 2 strokes!!!!

 

[I_THUMP]

The biggest 2 stroke Kawasaki still make is the Kx100! All there bigger range are 4 stroke.

 

[Flarry]

2 strokes arent really pitbikes but I must say the DS80 (2000 model) is the closest 2 stroke ive ridden to a pitbike, its actually pretty good, if I had an endless supply of cash I'd get one and mod it. Borrowed it from the nieghbours and gave it a beating on the track, its just like a pitbike but faster. Would be good with suspension mods etc.

If it had front fairings and no headlight/brake light it would look like one too.

 

[Fiddy@norway]

kawasaki is just better at making 2 strokes!!!!

Just gotta say I agree to some degree with sidney, In the last 10 years of production, honda made slow 2-strokes, both the 125 and the 250 were considered the dogs of theire classes, in those years Kawasaki owned the hondas on pretty much every point.
the honda is bulletproof though, but the kawasaki was pretty reliable too, my old -96 KX 125 is still going like crazy

 

[red_demon24]

^^^^^ i agree with what he said.
i dont think you will ever find a 2 stroke pitbike apart from those little pocket rocket things that you can buy for like 100 bucks but still that aint a pitbike.
if you think back in the day where there was no such thing as a china pitbike.
the pitbike on the market was the genuine thumpstar then china decided to make cheaper copy's.
and by calling it a "THUMPSTAR" makes sense as haveing them as for strokes cos there pretty loud and "thumpy" as for 2 strokes they couldnt call it a thumpstar they would have to call it a "rinnggstar"lol.
if that makes sense i dont think they will ever make a 2stroke thumpstar and i dont think one has ever been made unless someone bought one and then put a 2banger in it.
thats my 2cents

 

[Gureno]

i think reddemon has mad his point

these bikes are all in diffrent classes and were compared...well this happens^^^^

but when it comes down to it my kx owns the yz anyday.

and thats trialed

 

[dirt devil]

thanks

ah alrighty cheers for that aye just something bout four strokes that is really really not cool.....there 4 stroke haha anyway ill look into it, buy a bike and start rippin it up! cheers again

 

[motoXXX]

i thump every bike shop ive talked to this year as im looking at getting a 08 250f say that the kawasaki is BY FAR better then the honda

 

[Cactus Jack]

IF you're going to compare a 2 stroke to a 4 stroke pit bike ...... then it has to be a horizontal 2 stroke with NO expansion chamber and even only a 3 or 4 speed tranny .... as in PW50 to 100 cc four stroke ...... PW80/ DS80 to a 160 cc four stroke ....... the horizontal two stroke can be ported , bigger carb , higher compression but no boring , stroking or expansion chambers that supercharge the cylinder .......

As explained by these simple mathematical facts :

2 stroke 50 =

50 cc x 1,000 pulses per minute @ 1,000 rpm = 50,000 cc/pm
50 cc x 10,000 pulses per minute @ 10,000 rpm = 500,000 cc/pm

4 stroke 100 =

100 cc x 500 pulses per minute @ 1,000 rpm = 50,000 cc/pm
100 cc x 5,000 pulses per minute @ 10,000 rpm = 500,000 cc/pm

Vertical 2 strokes have to be limited to 85 cc compared to CRF150R ......

85 2 stroke =

85 cc x 1,000 pulses per minute @ 1,000 rpm = 85,000 cc/pm
85 cc x 10,000 pulses per minute @ 10,000 rpm = 850,000 cc/pm

150 four stroke =

150 cc x 5,000 pulses per minute @ 1,000 rpm = 75,000 cc/pm
150 cc x 5,000 pulse per minute @ 10,000 rpm = 750,000 cc/pm

So you can see that a CRF150R ...... HAS to be revved higher to make the same power that an 85 two stroke makes at a lower rpm ...... meaning they need higher valve train maintenance than a normal 4 stroke because of that fact ......

Now look at if they were 170 cc :

170 cc x 5,000 pulses per minute @ 10,000 rpm = 850,000 cc/pm

IF both engines were achieving 100% volumetric efficiency ... then they'd make the same HP at the same rpm ..... the ONLY cause of variances would be due to frictional loss or oil drag in the 4 stroke (that's why Honda and all the others went to a dry sump oiling system in their MX 4 strokes)

Peak HP = top speed ........ you need a certain amount of HP to pull a certain weight vehicle to given top speed .......

Any vehicle with more HP to weight than another can achieve a higher top speed ...... and vice versa .... torque = acceleration .....

Here's a few links that show that expansion chamber equipped 2 strokes achieve 104 % or more VE (= supercharged) whereas 4 strokes can achieve 99 % VE .......

2 stroke :
TFX Engine Technology - Power Tuning - Two Stroke Engines

4 stroke :
TFX Engine Technology - Opwer Tuning - Four Stroke Engines


crf150r vs cr85r - ThumperTalk

My 150r Eater - Planet Minis

140cc pit bike vs 65cc 2 stroke - ThumperTalk