Starting Big Bores

probably cost..just make a 250 and a 300 based off of it. not much demand for anything bigger..the 360 and 380 were both discontinued, so not even that size is wanted..

Sales.... bottom line....

Bikes like the KX500 and CR500 have never sold as many but then in the later years even less....yes a lot was because they were the same bike for the last 10 years but that's the reason, the sales were so low it didn't make sense for them to design a new one...

Also to add to that, most big bores were sold in Cali and now which now you cant ride a 2 stroke in the summer so even less bikes....

Just as a side note I raced many KX500s in the Cali, NV and Baja deserts....

But lets be honest they are not very rideable.... even the 380 vibrated bad.... if you are so fast or wanna make people think you have a big pair get a 501.... faster than a KX500 and way easier to ride

ALL TRUE BUT I THINK PEOPLE ARE STARTING TO MISS THEM I BET YOU COULD SELL SAY A 400ISH 2T TODAY BUT YOU WOULD NEED TO REFINE ALMOST ALL THE HELL OUT OF IT LIKELY NEED A BALANCE SHAFT E-START AMD [GOD I CANT BELIEVE I'M SAYS THIS] EFI

theres a few people that miss them...but to most they are a curiosity.

Sales , lack of development and no national championship class for the big bores killed them . When I was getting back into riding and looking at bikes , I really wanted to get another big bore but bought a 250 , newer design , more improvements . Maybe if the AMA and fim made the classes open to any engine , 2t , 4t but limit displacement to say 250cc and 450cc you might see more 2 strokes but until then what reason would the manufactures have to build any more big bores ? The 4t's were given a displacement advantage , why not level the playing field ?

I'm not fast, but there is nothing better than that surge of power hitting a corner in third and wheeling out shocking 4,5,6 an losing everything behind.

yea that 2t 4t displacement rule shit needs to go away run what u brung 265 [2MM over bore] and under and 270 and over

look at the bottom of my avatar, have a 2002 EXC380
they really are a great bike, their 360 was not competitive to the 360 Husky so the 380 was the answer
and a good one if I might add

I recently finished a build for a friend . It's an 81 Maico chassis , WP upside down forks with a disc brake and a 79 400 engine that I totally rebuilt . Told my friend how easy it starts so when I brought it back to him I had to show him . This engine had every bearing and seal replaced along with a new piston and ring set up to .0025 clearance piston to cylinder . Of coarse I cleaned every grounding point possible to bare metal , stator , engine mounts , coil mounts etc . So here it is , moment of truth , he's standing right next to me and asks " one kick , right ?" I didn't say a word , pulled compression release lever , held kill button down , gave 3 priming kicks , release kill button and gave it 1 good healthy kick and it fired up on 1 kick ... I was wearing sneakers .
not every big bore is an easy starter and some can be down right nasty to kick over . My buddy also has a Maico 685 that we have yet to figure out the starting drill , it was a brand new never run engine and there's a lot of metal to kick over but it will jump start fairly easy if you know how .

There's this fast-growing thread in a vintage motorcycle forum. It is basically about how to start a bit bore 2T without breaking your ankle or exhausting yourself. That may be explanation enough as to why big bore 2T production fell off. Throw in environmental regulations, noise complaints, noise regulations on public lands, and engine design enhancements improving performance of the smaller bikes. Not to mention the lack of comfortable ride-ability (for example, on my 400 there's an RPM where my vision literally goes fuzzy if I hold the handlebars too tightly), I'm pretty sure that at some point, everyone who wanted one had one, and everyone else was OK with that.

The owner of my local bike shop one time described to me that on an MX circuit, he would ride is 250 in the open class predominantly stacked with 500's, and win. He chalked it up to the 250 being more nimble in the corners. The big bores owned the straight shots, he owned everything else, and there just weren't that many straight shots.

i think you are correct...
altho about the 400 vibration, you may have a rich spot. now that my 430 is jetted very close the vibration levels are way down. amazing how richening it up a bit makes it vibrate.

I stab mine cause I still remember the broken foot.

Sales were never a problem, Kawasaki and Honda sold every KX and CR500 they produced. They stopped because they didnt want people buying cheaper, faster, lighter, more reliable bikes than the 450 4Ts they were developing, even if they were 20 year old designs. Racing was also a factor, although not in sales because the vast majority of 500s never saw a track, but from a political standpoint. Environmental regulations had nothing to do with it either, off road "closed course" only bikes, which covers all MX bikes, are not regulated by the EPA or any other agency just as NASCAR cars or Indy cars or F1 cars or Monster trucks are not regulated, they are purpose built race vehicles. Sound was not an issue either since 2Ts are quieter than 4Ts, much quieter. Yamaha still sells every YZ125 and 250 they produce, its an `11 year old chassis and a 17 year old engine, and have people waiting for more. The lack of 2Ts from the other Japanese manufacturers is purely a political one (Honda hates them and always has), because Yamaha, Beta, KTM/Husky prove that there is absolutely a market for them.

the clear outcome here is timing, if its knocked back a tad, the bikes seem to light up that bit easier.
the demise of the big bore twoie is simple, only 5% of riders are effective on one. ie "fast" . Everyone else has to wait for the straight bit before they can "open her up" thus making it easy to for smaller bikes to clean up. after the average big bore owner has replaced his third tyre and chain set in a season and their mates have stopped being "impressed" by the wheelies and roosts, they generally sell them so they can enjoy riding more on a more useable bike. Its was every young minibikers dream to ride the big bores until they had to live with one.

I was disappointed on my first ride of a 83 xc 500. it promised so much, looked sensational but I could tell I was sloooow. every time I tried to get the power on it just stepped out. and until 3rd gear on a good straight I don't think I got off the pilot jet!

I finally got to ride a 490 Maico and realised that there were"sensational" big bores... good useable power and nicely presented.

You have to remember the biggest market in the US CANT RIDE a 2 stroke for 4 months.... So the few they sold every year now is even less.... with margins decreasing, taxes higher and political pressure it wasn't worth it....

And the CR500 didn't sell worth a crap after they got dropped from the Nationals.... I was a manager at the largest Honda dealer in the 90s and we gave them away.... Honda never disliked any design but they want to win and will go whatever direction would win....

The reason the 380 went away.... the sales of it were low, extremely low..... Even the top guys chose a 300 over the 380 because of ridability.... the top speed of both were similar and even had the 300 geared faster and WAY less vibes....

I thought the 400 Husky was smooth compared to the 430 and way less than the 500

I'll never sell my '92 Honda CR500R, but at the same time it could never be my only or primary bike, its just too demanding to ride. The bike is a total blast to ride, and its easier to start than any of my Husky or Maico or KTM big bores, but its so powerful than you must have absolute focus if you want to ride it hard. If you want to cruise around at 75-80% its easy, its actually very easy to ride in the woods or on trails, but when you start to push and get close to the limit on an MX track the bike is just downright brutal because there is no margin for error at all. Just the tiniest crack of the throttle at the wrong time when you are going 10/10ths and you are on the ground faster than you can blink. The Honda steel frame chassis also head shake like a dog crawling out of a swimming pool. The Euro open class bikes are nothing like that, they are much more forgiving (which is not to say they are slow, they are not) and stable. A Husky 500CR could be my primary bike for sure, but not the Honda.

I think I was miss understood . I don't normally start bikes in sneakers but was familiar with this one and confident it was an easy starter and I do NOT recommend any one else trying to do the same . As for all you'd reasons , wouldn't they apply to any dirt bike not just big bore 2 strokes ? 1986 mxdn Johnny O'mara beat almost everyone in the 125/500 , the 1 rider he didn't beat , David Bailey on a Honda 500 . Ride ability , doesn't that also depend on the , machine and what you are asking it to do ? Yes , big bores can be difficult to ride but they can be a blast to ride . And in my opinion , sometimes you need to get a bike started , even by rolling it down a hill so you can see what it's like to know what improvements/changes need to be made .

View: https://www.youtube.com/watch?v=sAPxmw6Mi1U

the 400 husky is such a usable forgiving engine I don't class it as a big bore...its like a 300 kato...damn near perfect.

when they dropped them from the Nationals is the day that the big bore went (loudly) into the night

as a silly side note, on a bet I started my brothers 85 CR500 with flip flops, it really is about the method not the brute