I have led a sheltered life, in my sporadic trials carrer spaning close to 5 decades now i have only experience with a few engines. BSAs bantam cota 123 and ty250B s oh and a ty80

   Now recently considering an engine swap then deciding against it, i got to thinking did the members of this forum have any particular engine type or capacity that they would chose for their ulltimate air cooled twin shock project.

  What engine what capacity and why exactly detailing what it is about its power delivery torque respone etc etc you like so much about this particular engine.

I don't really have a favorite engine and I don't think engine performance in the conventional sense is all that important in the overall scheme of things. To me a bikes ability to turn and the performance of its suspension and brakes is much more important.

 

As far as engine performance goes what is critical I think is its ability to hook up. A low rpm torque response that is too sharp is probably worse than one that is a little soft in that it can badly affect traction and make riding difficult and tiring in the really tight and loose sections. I think almost any engine could be made to work very well with careful tuning and flywheel weighting, so it probably comes down to weight, gear ratios, clutch feel and so on.

One you can get parts for!

I always felt the Fantic was the ultimate aircooled motor with good performance (it spanned clubman to world championship level), reliability and longevity all of which was never quite surpassed by others. My preference was the 200 - a lot of people did not get on with the 240.

I was not surprised when, fairly recently, someone who knew one of the development team at Fantic told me that Fantic themselves thought the 200 was the best motor they ever made.

loved my old 325 bully, man that motor could pull.

 

I always felt the Fantic was the ultimate aircooled motor with good performance (it spanned clubman to world championship level), reliability and longevity all of which was never quite surpassed by others. My preference was the 200 - a lot of people did not get on with the 240.

I was not surprised when, fairly recently, someone who knew one of the development team at Fantic told me that Fantic themselves thought the 200 was the best motor they ever made.

 I hope your referring to The forwardkick Fantic motors , as they did not build the rear kick models  , had them built to their spec's though .

I love the motor in my 240 ... And I've got a Sweet 300 motor sitting in a box , along with it's expansion chamber that I may try someday , but I've ridden a few 300 powered bikes and I still like the feel/performance of my 240 ....

 But to answer the question , on a scratch build , As Cope said "one you can get parts for " A yamaha 250 can be dialed in to anything you want , and alot less expensive to build than any Fantic motor . But stock out of the box , I don't think you can beat a forward kick Fantic in whatever displacement strikes your fancy , But I too believe bike and suspension set up is more important , If it doesn't hook up , You dab or crash !!

 Glenn 

And there is nothing wrong with a properly built/tuned Honda reflex/tlr 200 motor either ....

Edited August 14, 201610 yr by axulsuv

I really like the way you can '' tune '' the TY 250 motor with the different model parts. I build a test motor that I setup in a standard 434 frame and tested it with the same suspension, brake, tire ect. It is easy to transform one from a diesel kind of power band to an enduro type of power. BUT I think the transmission is it's weak point, not the reliability but gear spacing. Also it's a wide and heavy motor. Don't get me wrong, I won't trade or sell my TY tomorrow, when you ride one for a while you get use to that, another great plus for the Yamaha: parts.

 

Guy

I hope your referring to The forwardkick Fantic motors , as they did not build the rear kick models , had them built to their spec's though .

I love the motor in my 240 ... And I've got a Sweet 300 motor sitting in a box , along with it's expansion chamber that I may try someday , but I've ridden a few 300 powered bikes and I still like the feel/performance of my 240 ....

But to answer the question , on a scratch build , As Cope said "one you can get parts for " A yamaha 250 can be dialed in to anything you want , and alot less expensive to build than any Fantic motor . But stock out of the box , I don't think you can beat a forward kick Fantic in whatever displacement strikes your fancy , But I too believe bike and suspension set up is more important , If it doesn't hook up , You dab or crash !!

Glenn

And there is nothing wrong with a properly built/tuned Honda reflex/tlr 200 motor either ....

Two Nations etc axulsuv. I meant made in the loosest sense as we use it here and was referring to the Minarelli motor which they developed, as the works boys didn't use the 200 Pro in the World Champs. Though the barrel was the same as far as I know from a recent write up. The 240 never really was the everyman motor the 200 was.

In the UK i would only use a engine that is relevant to the appropriate twin shock class.  You can't ride in the KIa national series with a air cooled mono engine in a twin shock frame!

Rotax has to be one of the most successful engines. Used in Puch, Gori, SWM, Aprilia, Armstrong + others ?

With hindsight Fantic seem to have gone in the wrong direction after the 200 Miranelli motor. The 240 was heavier, the 300 heavier again. Remember being amazed how Steve Robson in the North East could ride his 200 after getting off a 349 Mont. It now looks like Fantic were making there bikes more like the bikes of their competitors when their own product was better for the majority of riders.

Rotax motors don't seem to rev cleanly but if you can master riding in higher gears it's not really an issue. The torque is incredible and it's almost impossible to stall one

The 240 was a fantastic bike when it came out... I remember the time I first saw one. Even now it takes some beating, surely up there if not the best twinshock ever....

Interesting reading your coments here, One thing i have noticed is the apparent fondness of the smaller motors the 150cc fantic being popular and only a fleeting mention  of  a bultaco 325 and even the japs i expected them to get a much bigger mention.

 No suzukis RL  or kawasaki KTs And Hondas. interest seems low in these which supised me.

 I mean Fantic motor i knew they were a decent bike but the engines i would have not given then a second glance without reading these coments.

 

I would have to vote for a late model 325 Bul,very easy to work on and get parts for and smooth torque.That being said my experience is limited to Buls,my Ty250 A,TL125  and a KT250 that was borrowed to me for one trial.

 I have ridden one Fantic but it was a liquid cooled Section that had been ported and was a real brute for my limited skills.

 I agree with the suspension and handling comments and think that it comes down to what kind of power delivery do you prefer.