2 Stroke 400ex Rebuild Build up

[Frostbite]

Well some of you know i purchased a 2001 400ex with a blaster 2 stroke this last spring. So far its a decent bike but alot of the craftman ship in it is...well sub par. Alot of little things need work. So as we head into fall im going to tear it completely apart. Build it back up trying to get it to look and function close to what a 2001 400ex should be. I always loved the bug eyed look of the early 400ex so i will be using stock plastics. Im going to get creative with the wiring to run 400ex head lights off a blaster engine.

[Frostbite]

Ill post upsome tear down pics sunday afternoon. If money allows i would like to get a vitos 240cc kit in it. My CLYMER 400ex and blaster shop books came in today to help me make sure everything is done right.

[matt14c]

I agree a Yamaha motor is sub par! :p

How does that motor move that bigger machine? Stock blaster motor. Interesting swap and was definitly prolly cheap.

Good luck with the build. First Generation 400's are the best looking by far.

[MtnEX]

You know... I never thought about a blaster motor.
Easy conversion.


Myself, I think it would be nice to have something larger... the 240cc might be nice.

I'd like to have a 300cc dirtbike engine.
But I never checked to see if there is an air cooled one.

[F-16Guy]

Originally posted by matt14c
I agree a Yamaha motor is sub par! :p
You won't be saying that when 240cc's of pissed off blaster motor go screaming past you!! :devil:
You can make a blaster engine extremely fast! The Vito's 240 kit is a good idea. Do that with some good reeds, and you'll have a real sleeper. I bet that little motor shaved a few pounds off the old ex, too. I think Vito's or Ricky Stator should have a re-wound stator that would power a pair of stock lights fairly easily.

[BakerRacing40]

now there's something unique... and i can honestly say i've never seen this done before...

[rigger]

That would have to take a lot of weight off of that machine. I do not know how much the motors weigh but I have had both of those motors in my hands before and the Blaster motor is alot lighter.

I think it would be pretty cool with a big bore kit in it. Looks like it would be a fun ride.

[MtnEX]

Anyone know what the largest air cooled 2 stroke bike engine is?

[MyKe2g3]

Rofl this is like the Banshee with the 440ex engine in it that is on craigslist. Somethings just shouldnt mix bet itll be a fun project bike and fast but just plain nasty though.

A built 240 blaster motor is just as fast as a 250r.

I bet that thing weighs almost nothing, combined with the fact that motor is capable of producing 250r type horsepower, means for a hell of an MX quad. The blaster motors have a very wide powerband.

And not only is the motor lighter, you no longer need the oil tank/cooler.

MTN,

I believe the yamaha IT490 or earlier YZ490 are the the biggest 2-stroke dirt bike motor made, that is aircooled.

[bergoff]

that was the biggest problem with the blaster was it was to small. that thing looks like it would be awesome to ride. there were rm500 and a cr500. i think that the cr was only made for a few years air cooled. in 84 it was liquid cooled. nice bike and keep us posted.

[MyKe2g3]

A built 240 is about as fast as a stock 250r. I dont get why the owner put a smaller engine in a bigger 4 wheeler like that. Good luck with the 240 kit i still think youll be disappointed if ur looking for hp numbers but itll be a fun lil bike to have.

Originally posted by MyKe2g3
Rofl this is like the Banshee with the 440ex engine in it that is on craigslist. Somethings just shouldnt mix bet itll be a fun project bike and fast but just plain nasty though.


Hahaha I just looked that up. How stupid. You buy banshee's for their engine's, not their chassis. What a waste of a banshee frame and 400ex motor lol.

[GPracer2500]

Originally posted by MtnEX
Anyone know what the largest air cooled 2 stroke bike engine is?

Quite a few manufactures made air-cooled two stroke dirt bikes in the 500cc range in the 80's. There was the Suzuki RM500, Yamaha YZ490/WR500, (pre-'85) Honda CR500, Maico 490, and KTM 495. And maybe others. I've got no first hand experience with any of them but believe at least several of those models were/are legendary for being poor overall bikes with correspondingly short model runs. Powerful though. Probably too powerful for air cooling.

[Ted5986]

if you are looking for more power go with the factory 7 firebreather 240 cylinder. and as far as sub par goes....number 1 was that pipe made custom for the motor?? 2 strokes need that pipe to be spot on in order to make power and number 2 the fmf is garbage to begin with. if you have someone make you a custom pipe with that cylinder you will be moving pretty good.

fire breather 240 (http://www.factory7atv.com/PBengine.htm)

[MtnEX]

Originally posted by GPracer2500
Quite a few manufactures made air-cooled two stroke dirt bikes in the 500cc range in the 80's. There was the Suzuki RM500, Yamaha YZ490/WR500, (pre-'85) Honda CR500, Maico 490, and KTM 495. And maybe others. I've got no first hand experience with any of them but believe at least several of those models were/are legendary for being poor overall bikes with correspondingly short model runs. Powerful though. Probably too powerful for air cooling.

Yeah... I'd say so...

I was thinking there was a more recent 300cc dirtbike with an air cooled 2 stroke. But I think I was wrong...

I had the Kawasaki and KTM 300's in mind.
I think they are liquid cooled though.


But something like that might make a nice 400EX hybrid for cheap.

[Frostbite]

Originally posted by Ted5986
if you are looking for more power go with the factory 7 firebreather 240 cylinder. and as far as sub par goes....number 1 was that pipe made custom for the motor?? 2 strokes need that pipe to be spot on in order to make power and number 2 the fmf is garbage to begin with. if you have someone make you a custom pipe with that cylinder you will be moving pretty good.

fire breather 240 (http://www.factory7atv.com/PBengine.htm)

The Fmf is orginally for a honda 250r from what i was told. Stock pipes wont fit in the frame. Ill look into customs bit later on.

This isnt somthing i would have thought of or done ever.I just saw an add on craigs list for it awhile back and for what i picked up for i was happy.

[Frostbite]

BTW im looking to buy 400ex stock plastics and headlights. Or if interested will trade stock race cuts plastic and nerf bars.

[John Noftsinger]

I would look on net and find either a 2-stroke from street bike I think they are high as 750 cc in some of the older ones and have someone custom build pipes for it ther was a motor forgot the brand but it was 500cc,s and people were putting in 3-wheelers and calling them i think "Tigers 500,s" look up on net that motor was a beast (70hps) way to much for 3-wheeler ,but Id look in at old street bike motors from late 60s-early 80,s 2-stroke,there are so many maybe ship from other country for cheap price ?

[coreyownz]

looks like a cool build i had a modded blaster port and polish stroker pipe reeds everything except a big bore but one thing i learned was a well dont port and polish stock cylinder and stroke was snappier than a unported 240 so make sure you get a good port and polish job just me .02

[Frostbite]

Well yesterday i got the sub frame off to start striping it down, well from the pics you can see someone painted black over the yellow! Well come to find out the yellow is Powder coat. I wouldnt mind have a yellow frame but somebody just screwed that all up with a rattle can. So really i have no choice but to take the yellow off with the black.

I got half the sub frame striped, this is going to be alot of work doing the whole frame. Wish money wasnt tight or else i take it down to a powder coat shop and say, here you deal with it.

[MtnEX]

How do you get powder coat off?

[Frostbite]

MAC Die Grinder with a wire wheel brush on it and more patience then i care to have.

[TRXRacer1]

The early atc250r motors could be a fun easy swap. They'd kick the correct way for an ATV like the blaster motor. Lots of power to be had out of them.

[MtnEX]

Originally posted by Frostbite
MAC Die Grinder with a wire wheel brush on it and more patience then i care to have.

OUCH!!!

[MtnEX]

Originally posted by TRXRacer1
The early atc250r motors could be a fun easy swap. They'd kick the correct way for an ATV like the blaster motor. Lots of power to be had out of them.

Yep... that would work...

[Muzzgit]

A bloke down Esperance way (Australia) has a suzuki LT250R with Suzuki 250 MX bike cylinder/head/piston + ported and it rocks!

[Frostbite]

This Bike is now for Sale. I the frame has been repainted grey using construction equipment spec paint and clear coat. Like to get a thousand for it. Now has Stock 400ex wheels, front are new OEM. New G-Force rear axel.

[Foxhound013]

Like the other guy said powdercoat only comes off with a lot of grinding or acid. Sadly the acids that will do it cost, i think and don't quote me exactly on this but for 5 gallons i think it was 100 dollars thats the goods stuff. There isn't anything from the store that works to take it off we've tried everything because my dad does powdercoating here and there for people and it takes alot longer like a week, because we don't have acid, for him to get the time and put it into grinding it all down. Another way is sandblasting but thats supposed to be hazordous to your health and its a tad expensive to do yourself.

[TRXRacer1]

Originally posted by MtnEX
How do you get powder coat off? Comes off fairly quick with a sandblaster.

[BM@Ronayers]

How is the power of this bike? O, and Aircraft cleaner removes powdercoat.

[MtnEX]

Thanks for the removal info guys.

[Frostbite]

Power to weight ratio is extremely good

[Foxhound013]

Originally posted by BM@Ronayers
How is the power of this bike? O, and Aircraft cleaner removes powdercoat.

We've tried aircraft cleaner and haven't had a whole lot of luck with it. Sometimes it would work fairly well but most of the time it didn't work very well, it stripped a little off but not alot.

[BM@Ronayers]

I wonder how hard that motor would be to mock up on a 300ex?

[Frostbite]

The exhuast is the only problem i would see, mine has 250R pipe it barley fits. the stock pipes my work on a 300ex

[BM@Ronayers]

I just wonder how hard it would be to get the motor positioned right. I also wonder how the power would compare to a mildly built 300?

[Frostbite]

Id imagine if you bolted the rear swing arm to the engine and put a jack stand under it you can fab up the front mounts pretty easy. I dont know how fast 300exs are, i draged raced a 250ex and smoked it with the stock blaster engine, then i draged raced my own 400ex and held with it but the blaster/ex is greared lower so the 400ex blew by after it maxxed out. With a VITOS 240 big bore kit the hp numbers are close to a 450 from what tthere website says.

With a simple 240 top end, the blaster is similar to a piped 250r. When you start going higher compression and a 3mil crank, with a new carb and so forth, that's when you really get some serious numbers.

There was a guy on here that got 51hp on pump gas out of one. 61 on methanol.

[BM@Ronayers]

I swear that would be cool on the ol 300! I can see the swingarm being a problem though because the swingarm on the 300 is solid. The swingarm bolt would not be able to go through the engine.

[Frostbite]

Perhaps a 400ex swing arm will mock up?

[BM@Ronayers]

That is very possible. I know that the 450 swinger will but I am not 100% about the 400. The drawback is that I would need the whole rearend.

Originally posted by BM@Ronayers
I swear that would be cool on the ol 300! I can see the swingarm being a problem though because the swingarm on the 300 is solid. The swingarm bolt would not be able to go through the engine.

I adapted a banshee swingarm to my blaster a long time ago, and I had a similar problem.

But we were able to machine the part that fits on the engine very precisely, and it worked perfect. Basically just cutting a small part out of the swingarm.

[killer400ex]

my buddie has a yz 490 thats been bored over and let me tell you, that bike is scary fast, i can ride anything but that thing literally scares me, if you put a yz 490 motor in that frame nothing would come even close to touching it, seriously those motors are no joke and will put you in your place