1975 Yamaha MX400B 

You have a wonderful life getting to ride all these old steeds. Thanks for the memories

I owned a lot of dirt bikes back in the day and certainly had much more advanced than this but the MX400 was my hands down favorite. I could literally climb up cliffs with it. At speed though the infamous Yamahop from that primitive monoshock was very unforgiving. I still have a memory from it in a big knot on my collar bone that did not heal straight after mistiming a set of whoops.When I die and go to heaven I would love to have an MX400B waiting there for me, to blast across the desert in the sky WHOO HAH!

my heart melts to the sound of that thing...what a unique exhaust note..it screams cool..deffinately a special bike

Last time I was on an MX track was summer of 74, I rode CZ. The 1975 Yamaha is an iconic bike. It was the game changer in MX. Yamaha shut down production of the 1974 360MX earlier in the year than normal, and introduced the new 75 model with rear long travel mono shock. 1974 industry wide, top suspension was 7" front travel and 4" rear. Every other manufacture had to play catch up. CZ was owned by a communist government and had zero R&D money, and went away. The other Europeans like Maico and Husky went with lay down twin rear shocks until they could re-tool. Other European makes went under like: Bultaco, Ossa, AJS, and DKW. From this point on the Big Four Japanese makers dominated MX. Somehow John Penton stayed in business until 1978 when KTM's name went on the tank.

I was an avid dirt bike motocrosser back when these came out. One thing we learned quick was to not follow too close. That monoshock made that bike so tractable that you would get hit with a fist size rock right in the face if you trailed a MX400's six.

looks like it has a Webco head on it. the stock head have radial fins and they are very sparse and it did not take long to overheat it after hard riding on a hot day. these are very strong running bikes, I hopped up a 1975 DT400B with the MX400B top end, MX400B piston and a 38 mm carb from a 1976 IT 400C, this thing now rips and feels like I added more than 15 HP to it and no real loss in torque.

Right when I first started getting into dirt bikes about 3 years ago, there were so many classic 70s bikes for sale for super cheap. Now ppl realized the beauty of them and they’re rare. I’m 16 and can barely afford to keep my 97 Cr on the road but if I had the money.. dream bike

love those old 400,s had 2 of them back in the day nothing better .

For those questioning the year of this bike, It is a 1975 MX400B. My older brother and his best friend both bought the first ones to hit our local Yamaha dealer in 1975. I later purchased it from him. It’s a badass bike and all what he said is true of it’s power. We could wheelie that bike at speed for a 200’ or more with ease. The low first gear made for easy slow motion trials like wheelie as well. The one in the video is as original as it gets although the head is different from my brothers and his buddies bike. Maybe a mid year change or maybe just a replacement. It looks like a 1974 MX360 head to me. This was the first production monoshock, the YZ360 in 1974 had a monoshock but was only for the factory race team. This white MX400B came out as the first mono shock for production. If i I knew how to post a photo on here I could post my brothers [later mine] in stock trim and you’d see the difference in the head. Otherwise the one in the video is original except the added on fork brace.

Sounds awesome dude, love all your vids, keeping the dream alive. If I could leave Australia, and go anywhere in the world, it would be your shop and museum.

What NOSTALGIA 😁❤️ I had a 250 MX YAMAHA ... ‘75 ‘76 or ‘77 Don’t remember what year it was but just simply awesome ☝️

My first dirbike 15 years ago. Worked awseome for fogging mosquitoes in the yard 😊 👍

This was the bike I learned on......yup....steep learning curve. I ended up going thru two of them before I jumped to later bikes. Put on Maico 440 forks and had White Bros. set up the shock. This bike sounds rich as hell. Note the fork brace on this one....bent my forks because they were piss-ant tubes for a bike this strong; thus the Maico's. Really helped take the "Yama-Hop" side-step out of it. Bike only really hurt me once.....and it was my fault.....easy bike to ride. Great to see this video. As I understand it, the early MXB engine was later tamed a bit to make the first YZ400. If you didn't set 'em up right you could snab a ring in the port. The early MXB(mine) did not have a split intake port, soooo...... The 2-piece pipe was unique and made the thing easy to dismantle but could sometimes be a pain in the ass in terms of leaks. That's a pretty mint bike you have there, Ken. Would like to throw my 72 yr-old arthritic butt on the thing. Keep them videos coming......my everything hurts today. Hope I don't reach the end of the trail.......Tom

First New bike I bought great Enduro bike still have the owners manual for it love your channel

Your crazy as hex. But that bike looks fun and reminds me when i was a kid! Sounds 👍 good job

Easy starting due to the automatic compression release that Yamaha incorporated into the design. One good stroke usually did it....even in winter to ride in snow.

Minty!. So much for anything new now . I want those oldies.

That growl the bike makes is awesome

Awesome! I had the 250 version back in the day.

Ive still got mine. A cr450 stroked to 480cc and cammed is a good drag race in the dirt . kid don't come around me on that thumper until we crest 60mph.

The wife is watching this over my shoulder and was like ''OMG, he's riding it on those nice hard wood floors!'' LOL

I have a 1973 SC500 with a 74’ DT400 lighting kit. Street legal 😂

Friend of mine, now dearly departed had one of those...ideal woods bike...we called 'em 'stump-jumpers'. His had an issue that I was told was common with the MX bikes, he'd have it on a stand idling, and it would just randomly snick into gear, usually 2nd from neutral, no biggie if it was on a center stand, but if he had it leaning against a tree, it'd take off on it's own. He got out of the habit of using trees...

That thing is purring so nicely

That fork brace could be a lifesaver. Used to have the 125 version (without the brace) super fun little bike but even with the 125 the forks were close to their limit. The idea of the same basic frame but with a 400?

Sounds sick! It Growls for sure.

The rear tire looks totally bad ass on that bike!

She's tight sounds brand new

man that bike is clean is it me or do the old 2 strokes sound much deeper sound then the newer 2 strokes

Had one of those when I was 16, absolutely loved that bike. Much broader power band than a YZ 360 of the same year. Even though it was heavier than the YZ many racers preferred it.

Man I have to come see these bikes,love it

hell yeah that is about as good as it gets for a 2 stroke sound you would have to ride your home stereo to work to beat that sound sweet music any day very nice above and beyond good showman peace

Great bike i had one which i never sold it.

Sounds like that power band would be wild

The gas tank reminds me of an old xt. This bike sounds so unique

I dont care what any one says i love 2stroke nothing like high rpms power in a bike

Another beautiful example of a Yamaha Enduro. Good luck selling it guys!

What a monster it sounds great!!!!!!!😃😃😃👍👍👍👍

Wish I looked that good 1977👊🏻

This thing is a time capsule!

Just found a 78 gt80. It’s in great shape I got it running and cleaned up 35 yrs of dirt from it sitting in lady basement. What you think I should sell it for?

Great off road Enduro bike first new bike I ever bought

I've never seen this bracket, cool you had a few of them 🤔, she's a beut

Thats a beautiful bike. My dad had one and i had a hodaka 125. Those were great days. I seen my dad climb hills on that bike i couldn't climb on my cr500 a few years later.

My uncle had one of these.

Ride it up that hill!! Braaaaaaaapppp!!

It belongs in a museum on {ROUTE 66}...

I have the exact bike i just rode it toda

Another gem

so cool love it....

Ken do you have a YAMAHA XT 500 ....you have a great collection I'd love to visit your museum . watching from in the uk... Trump is in town the uk today.we need him.

You finally put a real bike on there.

Love it .

Geez Louise, is it always winter in all of your videos there ? Lol nice bike !

Pourquoi vous traduisez pas en français ???? Merci

That is a gorgious bigbore bike

i have one ,where do you get the plastic from?

How do I find we that older bikes you have for sale

I could never understand why a 2stroke brings out the devil side of any biker...😈...My side 2strk devil comes out just with the smell of 2t & the exhaust music..👹

Question Why a dirt bike has idle Race dirt bike has no idea unless you want to you need max power

Cant beat reed valve induction!

Sounds more mean than a Lion !!

My old bike .

MXs must've been woods racers?

Good2 ...

I tried to your web page to see what for sale and no luck

yammy beast..

Trick Fork Brace.

No offense, but the seat rework is a little iffy. Get rid of the lumps bra!

😍😍😍😍😍😍😍😍😍😍

I'd give the little finger off my left hand for that baby 🖐️😊

PFFFFT! you dont ride it like a Dirt Bike; crank shift crank shift fast as hell that front tire shouldnt even be on the pave! and you should be up over the handlebars: NOW! now you can experience what a Yamaha 400 MX is all about! I owned one

huh ? faster than a 250 ? in a different class ? well yeah, ALL of the 360's and up were faster and in a different class !!

Thanks for sharing uncle you are a interesting guy me and you have exactly the same interests in dirtbikes I love all japanese and European air cooled dirtbikes they were cool interesting fun times of lovely smelling two strokes that run on clean smelling oil like vegetable oil ,Castro oil ,belay oil it was all good but these days the competition smells bad

Belray was another good oil