2 stroke thread (with occasional F1 relevance!)

[J.A.W.]

Uniflow, what - if any - special lubrication measures does your selective transfer F.I. system require?

Do you rely on the regular 2T MX-style simple 'pre-mix' of lube/fuel..
..or have you incorporated a discrete injecto-lube metered/pumped to the set-up?

[Andres125sx]

A-125..
How can you possibly make the call - on what anyone else but yourself - finds boring?
Arrogance?
This is not an acceptable substitute for reasoning..

As I noted, my last dirt bike was a KTM 380 2T, & so no, aint no 4T 450 gonna impress me much, power-wise..

Here's an example of the kind of fun a bigger cc 2T provides.. https://www.youtube.com/watch?v=DxqPMR9MCx4

I did take the opportunity to have a ride on a 250 4T yesterday though, & it was - IMO - most def' "boring"..

... Antonio Cairoli, seven times World Champion, decided to compete with a 350 versus all the rest 450´s because that´s a beast with more power than needed, but you might find it boring...

Oh and if that video is funny for you, trail bashing with a MX bike then I understand your point of view, but that´s not MX nor the use a MX bike should receive, for that you´d better buy an enduro or trail bike, much better for that use. A KTM 690 would be perfect for that use, with around 70hp, a wider power band, much better traction, more power...

BTW, even Paris-Dakar bikes are now 450´s despite they use much longer gearshifts and they weight much much more with complete electric systems, double or triple tanks, navigation tools, reinforcements, etc, increasing the weight to around 140-150kg, but for you they might be boring at 100kg total weight and short shifting

[Andres125sx]

How much fuel would your 2T MX eat in a typical race?

Not sure, I think I could use a tank (7litres) for a whole day of practice, qualifying and two heats... maybe for the last heat would need a bit more, but I always fill the tank before each heat since a friend of mine broke a shoulder when the bike stopped just before a jump because it run out of fuel

But since MX bikes don´t have instrumentation I can´t say how much fuel they use with traditional mpg or l/100km measure. But 450´s could use a tank for the whole day and still have some remnant.... a friend of mine witha a crf 450 only fullfill the bike tank at the gas station, while I needed an aditional 5 litres tank for my kx250 2t

Our transfer port injected YZ250 ( 2T ) uses between 14% and 21% less fuel than a standard YZ250 under the same conditions. Same track, same riders, swapping bikes every lap, enduro / trail riding. Numerus track tests, real world.
Don't be too sure on the 2T not having the same traction as a 4T, ECU driven electronics in our EFI YZ250 are capable of missed injection cycles ( and other tricks ), making the 2T as good at hooking up, if not better than any 4T.

I´d love to test it!

I wonder what´s that of the missed injection cycles..... Traction control? Because I guess that´s not how the engine usually works

[FW17]

FIA should allow Formula 2 to be only for 2 strokes

a 3.4L V6 2 stroke using the Mercury or Evinrude block will make the winner worthy of a f1 seat and the 60 superlicence points.

[flynfrog]

would you two get a room. Lets talk about engines and cool stuff not bickering over what is more fun (a subjective term) to drive. Hell people like driving under powered Porsches for god sakes.

[J.A.W.]

would you two get a room. Lets talk about engines and cool stuff not bickering over what is more fun (a subjective term) to drive. Hell people like driving under powered Porsches for god sakes.

That's a pretty piece of irony right there f-f.. L.O.L...

Racing/watching underpowered Porkers race.. aint so much fun though, is it..

A 917 turbo, however..

[uniflow]

Uniflow, what - if any - special lubrication measures does your selective transfer F.I. system require?

Do you rely on the regular 2T MX-style simple 'pre-mix' of lube/fuel..
..or have you incorporated a discrete injecto-lube metered/pumped to the set-up?

On the YZ we use a small solinoid valve that over 60% throttle opens a small jet to let oil into the inlet. Sort of an autolube.
On the F9 I don't bother, the injectors seem to spread enough oil ( castor mixed into the fuel ) around the case to keep things lubed.

[Richard]

A 917 turbo, however..

... does not have a two stroke engine.

Wow - I've actually mentioned 2 stroke engines and cars in the same post. Who'd have thought that possible in this thread?

Feel free to carry on that theme, I'll remove bikes left against these railings.

[J.A.W.]

R, if the 917 had had a 2-stroke engine, then likely it would've been banned.. for being too much..

Ah wait on.. ..it was.. anyway..

Funny story, I was riding one of my race tuned 2T 750cc Kawasaki powered bikes at a private track session,
& one of the Porsche guys there was keen to have a go on it - so I got a fang in his RSR Carrera in return..

That was a bit of fun, for a car.. ..not 917 fun, mind.. but fun anyhow..

( & Uniflow, thanks for the lube reply)..

[J.A.W.]

Feel free to carry on that theme, I'll remove bikes left against these railings.

I'd be a bit careful - if you seriously want to "remove bikes" - R, some biker-types likely won't take kindly to that..

[autogyro]

R, if the 917 had had a 2-stroke engine, then likely it would've been banned.. for being too much..

Ah wait on.. ..it was.. anyway..

Funny story, I was riding one of my race tuned 2T 750cc Kawasaki powered bikes at a private track session,
& one of the Porsche guys there was keen to have a go on it - so I got a fang in his RSR Carrera in return..

That was a bit of fun, for a car.. ..not 917 fun, mind.. but fun anyhow..

( & Uniflow, thanks for the lube reply)..

At all the run what you brung meetings I have attended, the cars always lapped faster.
Perhaps one day we will find a way to make bikes corner as fast as cars.
Aero?

[Pierce89]

A-125..
How can you possibly make the call - on what anyone else but yourself - finds boring?

As I noted, my last dirt bike was a KTM 380 2T, & so no, aint no 4T 450 gonna impress me much, power-wise..

Here's an example of the kind of fun a bigger cc 2T provides.. https://www.youtube.com/watch?v=DxqPMR9MCx4

I did take the opportunity to have a ride on a 250 4T yesterday though, & it was - IMO - most def' "boring"..

JAW. Unless your KTM 380 2t is highly tuned, it has less peak power than any of the full face 450s, as current MX 450s make close to 60hp at the rear wheel. A KTM 380 2t is an off-road bike with a much less aggressive engine than an MX bike.

[FW17]

A-125..
How can you possibly make the call - on what anyone else but yourself - finds boring?

As I noted, my last dirt bike was a KTM 380 2T, & so no, aint no 4T 450 gonna impress me much, power-wise..

Here's an example of the kind of fun a bigger cc 2T provides.. https://www.youtube.com/watch?v=DxqPMR9MCx4

I did take the opportunity to have a ride on a 250 4T yesterday though, & it was - IMO - most def' "boring"..

JAW. Unless your KTM 380 2t is highly tuned, it has less peak power than any of the full face 450s, as current MX 450s make close to 60hp at the rear wheel. A KTM 380 2t is an off-road bike with a much less aggressive engine than an MX bike.

A KTM 250 2t is 50hp off the showroom

[Andres125sx]

A-125..
How can you possibly make the call - on what anyone else but yourself - finds boring?

As I noted, my last dirt bike was a KTM 380 2T, & so no, aint no 4T 450 gonna impress me much, power-wise..

Here's an example of the kind of fun a bigger cc 2T provides.. https://www.youtube.com/watch?v=DxqPMR9MCx4

I did take the opportunity to have a ride on a 250 4T yesterday though, & it was - IMO - most def' "boring"..

JAW. Unless your KTM 380 2t is highly tuned, it has less peak power than any of the full face 450s, as current MX 450s make close to 60hp at the rear wheel. A KTM 380 2t is an off-road bike with a much less aggressive engine than an MX bike.

A KTM 250 2t is 50hp off the showroom

The scale is not proportional I´m afraid, or 500 2t should be around 100hp when they around 60 as much

What I mean is from 250 category bigger engines do not increase peak power at same scale, their power band is wider, flatter and more powerfull at low revs, but peak power does not increase that much

So peak power is similar, and as Pierce said, that 380 is an enduro bike, not an MX bike, and enduro bikes are a bit less powerfull than MX ones, with a softer response to improve traction and easy of use, longer gearshifts... Moreover, usual enduro bikes use MX engines adapted to enduro, but the 380 was born as an enduro bike, so its engine was not built trying to reach highest possible peak power, but ease of use probably, wich means flatter powerband instead of high peak power.

Only problem is some people is obsessed criticizing 4t´s, but I´d bet a salary that 380 does not have one single horse power more than 450 mx bikes.... and I´ll ignore 450s apply its power a lot more efficiently to the ground what means they will accelerate way faster to that old 380.

[Brian Coat]

I love those 2T dirt bike engines.

I had an old RMX250 (which I was rubbish on).

The world's most efficient piston engine is a 2 stroke so they can't be all bad.