The one in the pic above? .40.

[QUOTE=Storydude1;7898259][QUOTE=Smokeyr67;7898170]I didn't care about smearing her, it's just that she had a habit of sitting bolt upright in the middle of a bend! Gotta say, that for some strange reason she did prefer riding on the back of the 2 stroke....

That thing is awesome! Without knowing the driver skill or setup there's no way to really compare it, but as a toy that 4-stroke is sweet.

Just for a talking point, here's a (several year old) dyno comparison between 2-stroke and 4-stroke motocross race bikes. Today's chart would look similar, just the numbers would be bigger. The top group of lines are the 4-strokes.

2-stroke vs 4-stroke MX dyno image


Note the 4-strokes are larger displacement, yet they rev higher than the smaller 2-strokes. If you've ever ridden motocross bikes what you'll notice is the 2-strokes build rpm faster, but the 4-strokes have significantly better traction and hookup and the result is the 4-strokes are indeed much faster on the track. Acceleration through and out of corners is much better, jumps with little or no run-up are much easier, you can go faster on slippery tracks, etc.. I would think the benefit to an RC car would be similar. The catch is displacement; it takes a little more displacement for a 4-stroke to get similar horsepower to a 2-stroke, but the torque curve is much smoother and the power is much more usable. At least on a race track. Are there displacement limits in RC? Would it be legal to race a .4 4-stroke against a .21 2-stroke?

This is not correct. The (very old) rules of MX racing allowed 450cc 4-strokes to race with 250cc 2-strokes, but back in the day before 4-strokes were developed 2-strokes had such a weight advantage that 4-strokes were not competitive. FF several years, 4-strokes developed and got much more powerful and much lighter, not to mention made better power, and (in 1998 I believe..) Yamaha entered the series with the first hand-made YZ400 4-stroke and promptly won the championship. Horsepower wars drove the engines up to the 450cc limit allowed by the race series (read: marketing) and now the 4-strokes make so much power that the 2-strokes of the allowed displacement don't have a chance. I've ridden both, and 4-strokes are soooo much more fun to ride! I'm never going back 2-stroke. It would be really cool to see similar development for RC, but I don't know if there's enough cash to make it happen?

Search Youtube for "losi 4 stroke" should be the first 2 videos that come up. There of my 4 stroke converted Losi 8T.. Still in the testing stage, running a $80.00 .52 converted plane engine Tell you one thing, these 4 strokes will burn a clutch up in a few days! If i could get the power to the ground, id switch to racing only 4 stroke. Im also getting 12:30 to a tank, and gas is cheaper

Well, here's my 2 cents.

Of course, I will accept change back.

4 strokes (Motocross wise) have dominated the scene.

So, with that in mind, it can be done and has been done for some time.

Also, Just because the video looked like it was hard to disassemble 4 stroke

doesn't mean by this evening, a true R/Cer would not know how to have that

thing taken apart and put back together blind folded. I know, If it were mine

I would by tonight..

Also, RPM is a problem now, but, after some time, someone would work to

resolve this by gearing or a better built engine.

And as for Rotary engines, I'm all for that as well. They like RPM. (Althought

I don't think they have much on the bottom for power)

20 minutes of run time is definitely something I would be interested in.

I would also wonder if it would last longer between rebuilds.

Give me the plans, I'll mill it up..



RotaryNut Maico 490 or 500. What a real mans bike.

Image that engine updated in a new frame bike.

Wooo Mama...

I put together that one above from more parts than shown in the pic in about 30 min.(I tore out cam and followers)

It's not hard at all.

HEY DOC, tighten your hernia belt and put extra velcro on your depends, here you go!! check out these beauties!!!!!
http://www.maicointernational.com/html/mx-2010.html

.. wrong..........four strokes need nothing but a straight pipe.......no expansion chamber needed...so there is a 100.00 item off your car/truck......

Well, some one mention they don't spin up as high.

Hmm. Tell that to Honda. Where does the CRF-450 spin up to??

The airplane engines are pushrod engines at that.

No overhead cam like the motocross bikes.

Less parts should equal higher revs not to mention possibly longer life??

Maybe that part is a matter of a better built part.

Someone should consider turning this industry on it ear with this project.

Most modern four strke MX bikes hit the rev limiter at around 12,000-13,500 rpm.

Where did I say Expansion chamber?

I said Baffle.

And Nitro RC 4 stroke motors need a baffle of some kind to slow down exhaust pulses. Unless you like roasting 20 dollar exhaust valves every 1/2 gallon.

I've been flying planes with 4-strokes for a while now. Some additional benefits that have been overlooked are the fact that they are SUPER easy to tune and that once they are set, your rarely play with the needles. I've had my Saito for ~8 gallons now, reset the valve lash once, and beyond that have done nothing. I haven't even begun to think about a rebuild.

You have to take into account the motor that losi is running is a bone stock air plane motor...no where near intended for off road...could you imagine a four stoke motor made for the off road market....it would make 2 stroke a thing of the past...i am all for it!!

Your right, all i run is a straight pipe. Been fine for over 3 gallons so far.