Are there any two stroke bikes in the Dakar this year?

Surely something like a KTM 300 EXC would be pretty competitive, reliable and simple to fix if anything went wrong?

MitchMan

As would be a Honda Cub50...

Mixed fuel isnt available at the stops, so you would have to carry all your oil for the day and mix it as your filled up, not terribly practical.

Good point, however at 1:60 mix ratio the amount of fuel for the day probably wouldn't be that huge? It certainly wouldn't weigh as much as the additional weight difference of the 4 Stroke Bike.

Is that the only reason then stopping the 2 Strokes from competing?

MitchMan

the 690's can carry 34-36l when they need it.
wonder how much a 300exc would need to carry to go the same range??

I think a 2 stroke is not desirable for 3 reasons:

1) Half the Dakar is paved or at least untimed and open and boring, usually. That's a lot of km both for wear and tear and also for discomfort.

2) Power and power delivery: The big 4 strokes have an edge both on power and how it is delivered for carving up two track, which is the order of the day.

3) Fuel Economy: my 300, ridden at a fast pace and on the mainjet, burns substantially more fuel than my 530 ridden alongside it. Both are jetted to the best of my ability...

Don't get me wrong, I love the 2 strokes, but I'd hate to sit on one a few hundred klicks of pavement a day, between the good bits no less...

This question was (kinda) raised last year too...

Gerard Barbazant made a career (several times IIRC) of trying to get a 125 EXC to the finish... and as Rallye pointed out below... he used up a lot of pistons, cylinders etc. in the process...

Another guy from France named - Luc Grajwoda (spelling not quite sure) - made a habit out of riding a monocoque framed KX 500 creation in the Dakar and various other rallies in the early to mid nineties...

The thing used to vibrate that much that it often split/fractured the welds on the chassis and aluminium fuel tanks/subframe construction... and his eyeballs were still going up and down a half hour after he climbed off the thing at the bivouac of a night...

So basically the answers to all your questions are summed up nicely in Ned's post above...

Quote:
<TABLE border=0 cellSpacing=0 cellPadding=4 width="100%"><TBODY><TR><TD style="BORDER-BOTTOM: 1px inset; BORDER-LEFT: 1px inset; BORDER-TOP: 1px inset; BORDER-RIGHT: 1px inset" class=alt2>Originally Posted by rallye
a french dude Gerard Barbazant tried for many years to finish the dakar on a ktm 125 exc with a 28 liter tank fitted to it , i don't think he ever finished one but went through many a piston tying.

</TD></TR></TBODY></TABLE>

This may be his taken in Barcelona at the start of the '05 Dakar, KTM125

Honda had a go at a 2 stroke Dakar bike in the mid 90's too.

With all the talk of developmental direct injection/FI two stroke motorcycle engines back in vogue of late... the EXP Honda idea might come out of retirement for the Dakar in the near future again...?

Funny that Honda, killer of 2-strokes in any other form of racing, actually built that bike. Direct injection engine, I believe.

It would be very interesting to see a modern technology effort to race a 2-stroke though, I would be very interested in seeing a KTM 300 take a shot at the Dakar. After all, 2-strokes have come a long way.

LOL, I know how the poor guy felt. I have "lost" more than few parts of My KX500. Really sucks when you kill it in the bottom of a ditch and realize your kick starter is no longer part of the bike.........

Or that the only reason that your bike has not been engulfed in flames (the rear aluminium monocoque subframe/fuel tank has split and is leaking fuel directly onto the red hot rear exhaust pipe)... is that you are still travelling across the desert floor at 80 km/h plus... and the breeze is wicking away the flames from the 30 odd liters of fuel you are seated on... :eek1 Don't slow down my friend... don't slow down!

By the time you hung all the added weight on a 300, ie roadbook holder, nav equipment, large fuel tanks etc, the poor thing would really be wheezing by the time you got to the dunes. And an XC would be a poor choice as well. EXC would be the way to go. I'm one tooth up on the CS sprocket on my XC and it's all done at 75mph.

Don't forget the marketing aspect of bike choice as well: Dakar, like any MotoGP, supercross event, or motorcycle tradeshow, is an opportunity for companies to show off the 'best and brightest' of their motorcycle stable.

If Honda, KTM, Yamaha,... want to sell four strokes, and there is no doubt that every company does, the racers will be atop four stroke race bikes.

KTM is very active in marketing its two strokes in enduro and off-road racing.

Hey Neduro,

When you refer to the 4 stroke having an edge are you refering in general to the larger bikes, 650cc plus or the 450's or 530's. Now that there is the 450 limit in place for pro's in 2011 and the rest of us 2012 onward can we disregard your point 2 or do you think there is still too much of a gap.:huh

If a 300 KTM is close enough to the 450's in terms of torque etc we would just be left with comfort and fuel range.

When you say that the 300 is way more thirsty than the 530, what sort of riding did that involve. Was it a thrash or were you short shifting and riding the torque.

Neduro's comments or others very welcome.

It has been done (with varying degrees of success) and in light of the 450cc fourstroke restriction rule (2011/12 onwards in Dakar*) it would seem (as you point out) that it could be an alternative.

Here is a 1990 perimeter framed KX 250 (rally modifications and a KDX 250 motor) as ridden in the 1990 Australian Safari by Allan Cunnynghame to a 5th place (all XR600's in front of him).

(sorry about the faded old print)


The minimum fuel distance of that event was 300km (50 km's MORE than todays Dakar spec.) While it is true that did not include the same (fuel consuming) soft sand dune running that Dakar typically includes... but the bike still required a capacity of around 35 liters to go the distance.

The little KX/KDX was in it's element in the tighter or more technical sections (especially when the fuel load got lower into the stages), compared to the larger capacity fourstroke bikes of the day. Talking to Allan about it afterwards, he said that the hardest part of riding the thing in a rally (as Neduro alluded to earlier) was in fact; the long monotonous transports... the vibrations of the little 2 smoker were "mindnumbing" apparently.

This was 20 years ago... with some modern rally technology (lower COG tanks, cush rear hub etc.) maybe a 300cc two stroke is not such a silly alternative agains a 450cc fourstroke at Dakar*??

*The up to 700cc single fourstrokes are still (at the moment) allowed to compete in the other FIM rally events.


So barrier911, why not throw a larger tank, some navigation gear and a cush drive rear hub on an EXC 300 and head of to the next NRE with Hogwild and the boys to do some "real world" field research... ie. run it in rally conditions against other 450 and 690 cc rallye bikes?

Thanks! Troy, like I need any more encouragement to plan on entering the 'Big' one, Dakar, I mean. Now I've got you egging me on to rise to a challenge. I beat myself up every day deciding on what rally to enter next and which year to go for the Dak.

You may have seen a number of 4 stroke bikes I've built in to 'rallye bikes' on JMo's thread but I've never even ridden a two stroke.

The KTM 300 as a bike for Dakar interests me for a number of reasons....

• It's different and would raise some interest. (hopefully not for all the wrong reasons) (Eg having to change a piston and rings at each mid stage re-fuel! )
• Stories of the top end lasting upto 300hrs without work.
• Runs cooler.
• Weight.
• Far simpler and quicker maintenance.
• Ability to carry a top end overhaul kit, piston etc and repair on the fly. How many guys have gone out of the event with a holed piston or dropped valve.

I am guessing that the stroke and bore could be increased to add torque without even getting close to the 450 cc limit.
Higher torque should decrease revs, wear, vibration and fuel consumption. Or am I dreaming!!!!

As another first I believe it could also be 'Christinified!' That is AWD like my 08 530...

• I know I could suffer the vibes for a Dakar finish and maybe more flywheel weight would help. Mr Renazco would be getting a call.
• I know the Christini kit on my 530 dramatically reduces the requirement to rev in the soft sand, keeping the front wheel light and requiring a ton less fuel in those conditions.
• I know Safari make a 9 litre rear tank or even the Meca twin tanks would help with some creative thinking to reach about 30 litres as a total.

Now I still need to decide which rallye to enter next, which year to enter Dakar and Now which bike to build next, thanks Troy!

You might want to call Dave Fretigne over at Yamaha before you go too far down the two wheel drive route for a rallye bike...?

I know it's a different system to the Öhlins concept that Yamaha employed on the WR 450 F, but asisdes from the increased weight and some dubious reliability apects from having the front drive as well, there were some mixed reviews on the "high speed" handling traits in a rally application. No doubt though, it would give you better traction, climbing (and interesting to hear your increased fuel economy theory) in the soft sand dunes.

Yeah, I'd rather work on a 2 stroke, than a multi-valved, chain and cam driven, titanium wonder fourstroke motor out in a bivouac situation too...