Except for the Bultaco Lobito*, there are no bad dirt bikes. Some bikes are ready made to win races straight out of the box while others may need a bit of help to get results. Seeing Andy Caldecott win with amazing ease on an "evil" TM400 and "slow" TM250, Boagy win 125 races at will on, of all things a Rickman Zundapp and that guy at the Conondale Nats on the XL500 sticking it to Belly convinces me that any bike can be made a winner. Not every rider can unfortunately!
The TM/TS400 Suzuki is indeed a dangerous beasty but with the advantage of nearly 40 years of playing with the things we can now turn them into serious race tackle with just a few parts upgrades (
full circle TS crank, modern ignition, modern tech pipe, decent forks or fitting PD or Gold valves, and a decent set of shocks).
http://www.mccookracing.com/articles/firko_rogerSuzukiMe.htmThe YZ 490's problems can be greatly lessened with a bit of creative head/carby and pipe work. Methinks the 490s appearance on the bad list is because it replaced such a great bike. People expected an even better machine than its predecessor but unfortunately the YZ 465 was a
great bike with a reputation that the YZ490 couldn't hope to live up to. It was merely a
good bike when people were expecting a
brilliant bike. It's a similar situation to another notorious 'bad boy' bike the '82 490 Maico, which followed the most reverred open class bike in MX history, the '81 Maico 490. Some unfortunate quality control problems, extremely bad press and tainted the '82 Maico placing it on many critics worst bike lists when in actual fact, once the problems were sorted at factory level (
after the first month of production) the '82 Maico was a superb ride, possible even better than the legendary '81 model. Unfortunately the press and coming in the wake of a legend ruined its reputation forever. Today, the 82 model Maico and the YZ490 are half the price of their earlier brothers but can easily be made more than their equal.
*
I should take Hoonys lead here and explain to Bultacophiles that I don't hate Bultaco Lobitos at all. After I wrote my now infamous 'Julio Inglesas' piece http://www.mccookracing.com/articles/firko_JulioLeavesMeCold.htm describing my first day experience with my own Lobito, I've become the victim of scorn from Bultaco owners Australia wide. el Presidente of Club Bultaco, a bloke with a Polish name I can't pronounce, went into a rabid, spiteful and possibly libelous campaign against me in the Club Bultaco magazine, showing an unbelievable lack of understanding of the concept of satire or a smidge of a sense of humour. That's why I want to take a Lobito, a pound of Lan Choo, a nice plate of Cocoa Fluffies and the Hillsong songbook to this years Bultaco Rally. There are some fences needing rebuilding and I need to feel the love of the Bultaco community. 
