What do you think is the best motor ever fitted to a dirt bike?

[Matador107]

A BIGGUN BUT WHY?
From my fading memory bank and long ago English Motor Cycle Newspaper. Maico had a 700 and it was entered in the ISDT 6day competition,I'm guessing about late 60's,this was when the factory teams would have mechanics and fresh bikes jump out from behind trees in the forests of Europe. How you would kick it even with  a decompressor is beyond me,never mind the power.

That newspaper was weekly delivered into Aust and was the best ever,too bad about my tech study,it had it all.

[OverTheHill]

my 500 matchy was 'so' reliable that when it broke the oil feed pipe to the valve gear i just bent it & tucked it under the tappet cover [pushrod big cover] & carried on for the rest of the ride. Broke at the start of the day while leaving town but buggered if i was going to go home & have all my mates carry on. Not sure how it survived but wasn't complaining at the end. My vote today goes to the AMC range of motors [till i think of something else], even ran a matchy rod in my B33 coz i broke two bsa rods with a hell of a mess. While i'm at it, my metisse T100/5TA box would have to be bullet proof. We used to have Le'Man starts [if that's what it's called], think someone held the bike with motor running then we'd run as the shot gun went off & i'd do a superman leap on while stamping on the gear lever minus clutch at the same time [down for first]. Never heard the "Dogs Barking" or complaining.

[Lozza]

production run and model span doesn't make a great engine. thats just company policy and engineering. race or gp wins and world titles is what counts.

[EML]

Lozza, that sounds like the car magazines COTY award bullshit. Give them a great write up in the mag OR worse have a win at Bathurst and we'll sell 'em like hot cakes.
My line of business is to repair cars that have been sold to folk on false promise and to keep them running ....without send the poor buggers broke.
Too many of them are ripped off at the sales end...new and used and then have to live with the consequences.
A good engine is one that lasts past the manufactures expirey date and goes on to be used in plenty of different models.
Ask a new owner of a Captiva what they reckon at the gas station. Ask an owner of any of the new generation of Nissans with French engines...they will be verbally sick all over you.

[firko]

race or gp wins and world titles is what counts.

You have to be kidding Lozza....So you reckon a motor has to be a winner on the race track to be a good engine? I doubt that many races have been won with the 4.7l V8 in my Jeep Grand Cherokee but I bet that engine will still be running hard in another 200 000k....much longer than the tin box it lives in . Moving back to dirt bikes, the DT175-200 wouldn't have won many GP's to my knowledge but how many million of them are still running without a hint of trouble throughout the world?  Methinks you might read too many magazines Lozza.

[Simo63]

Ask an owner of any of the new generation of Nissans with French engines...they will be verbally sick all over you.

Apologies for getting off topic however it's interesting you say that.  My Aunt purchased a new Ford Territory with the Peugot V6 and it dropped it's lunch at 7000kms ..... and then Ford wouldn't warranty it ... nice one 

[Davey Crocket]

I'm with you Firko, an engine proves itself by it's longlivity and ability to be modified and all the various applications its used for...shit, look at the 283 Chev engine, was never designed as a race engine but evolved into probably the worlds most winningest engine....302....327...350.....you name it and it got used for it....bit like the DT1.

[firko]

The small block Chevrolet would have to be the best engine ever made period. All of the manufacturers have made engines to challenge it, some came pretty close, but 55 years later the old small block is still going strong on and off the track.........apologies for the sidetrack
                                                                           

[Lozza]

race or gp wins and world titles is what counts.

You have to be kidding Lozza....So you reckon a motor has to be a winner on the race track to be a good engine? I doubt that many races have been won with the 4.7l V8 in my Jeep Grand Cherokee but I bet that engine will still be running hard in another 200 000k....much longer than the tin box it lives in . Moving back to dirt bikes, the DT175-200 wouldn't have won many GP's to my knowledge but how many million of them are still running without a hint of trouble throughout the world?  Methinks you might read too many magazines Lozza.

I don't read car/bike magazines at all these days, your average Toyota diesel engine will do about 400,000 km without a spanner put to it, but that doesn't make them the best engine ever fitted to a car. DT 200 is a good engine as I have said before but a long long way from the best engine. A DT 175 engine is a complete shitter. The reason a DT 175 runs for ages is they make no power and never will. A few learners and kids running round paddocks won't find the limitations of an engine(or a bike) like international level rider in international competition.

[firko]

Lozza, using the same logic, outright race track performance is only one criteria involved in what makes a great engine. In fact, I think race track performance would be the least important facet of a successful engine design. The most important aspects of an engines design is performance at a number of differing criteria such as acceleration, torque, tractability, reliability, economy and ease of maintenance. Some of the best ever race engines such as the Cosworth V8, Offenhauser, Renault F1 engine, Keith Black top fuel engine and many more are brilliant at what they were designed for but would fail miserably at most other tasks. It's a horses for courses thing but to me the mark of a good engine is one that can be adapted to perform any number of differing tasks with reliability and ease of maintenance. The basic pushrod Chevrolet small block V8 ticks every box for car engines being used in everything from trucks and taxi's to Grand Prix winning open wheelers, pro stock drag cars and all points in between. The simple two stroke air cooled DT1 Yamaha single fills the dirt bike aspect of what an engine can produce with smart and steady development. It powered countless commuter bikes in the seventies, introduced a generation of baby boomers to the joys of dirt bike riding that continues today, has powered everything from American short trackers, Aussie sliders, road racers and even the TY Yamaha trials engine is pretty damn close. The engine even achieved a world motocross Championship in 1973.....all from the same basic 1968 design. Both engines have one common denominator.........versatility, and that's what I think makes a great engine.

[Tim754]

To quote Firko " It's a horses for courses thing but to me the mark of a good engine is one that can be adapted to perform any number of differing tasks with reliability and ease of maintenance"." versatility, and that's what I think makes a great engine " regarding the DT250 Yamaha, That is exactly my reasoning's for selecting the Triumph Unit (and pre unit) 650 and the Honda  K/F series CB750 Fours.

Is your selection versatile ? ie. Motocross/scrambles, enduro, trials ,trail rides, road racing, speedway ,long track ,short circuit, AMA flat track, ice speedway , rallying, hill climbs, drag racing etc etc
Reliable ? or does it need a fleet of factory technicians to rebuild it after ...every...outing.
Can you preform the basic maintenance it needs ?

 Maybe add these items to your thought trains.
Could you race bog stock as you received it from the shop or did you have waste lots of time and money to try to make it work for you?
How was the power delivery and the handling ? ( to be fair think relative to the era ) . Cheers Tim754

[Nathan S]

For how long is the Beta Betta for Nathan, LO
the KTM300 is bulletproof.

So far, so good. Did I mention the starter motor works too? 

[evo550]

The real answer is 2013 Beta 300.
To quote discobob: "I've spent a year fiddling with my KTM300, and the stock standard Beta is at least as good".

It's only as good, because like all the other 300 manufacturers, Beta are trying to emulate the KTM.
Who is "Discobob"

[EML]

Tim's correct about the Triumph 650 and by default the Yamaha 650....used in all application (including pumps and saw benches) and can be bombed to the hilt. Also the Norton to some degree. That must make the 650 parallel twin something of a 'right' design.
The GR650 motor I've just fitted is the next evolution of that same design although by the time it was built the V twins had become smaller/more compact and could be fitted into the same space. Time will tell how they go. ( I think HD are working on one  )

[firko]

As the owner of both 500 and 650 unit Trumpy motors I agree that it's been a hearty, well designed motor only let down by the sixties and early seventies British engineering death wish. I knew nothing about Triumphs until I had a lookie inside my little T100SC 500 and saw how simple a design can produce such great performance. The 650 has yet to be pulled down but their reputation speaks for itself. The Trumpy is the DT1 and small block Chev of four stroke motorcycle motors......versatile (there's that word again)