Help with Hybrid

[YZ400EX]

Ok guys here is the deal..I am getting a GREAT deal on a 99 YZ400F bike here soon and was thinking of putting the motor out of it into my 400ex. What I am wondering is how hard woul it be to get the motor in there and would it really be worth it since the bike is a 400 too and not a 450? I know that I would have to have special mounts done and possible frame mounts relocated and stuff like that, but what else?? I know I need a radiator and some other odds and ends..Could I jyst use a 250R rad and figure out where to mount it..I am new to this whole hybrid thing and figured people on here know alot more about it then me..any infomation would be much appreciated..Thanks

[wilkin250r]

It's much more common to put the YZ motors into 250r frames than into the 400EX frame.

But, the YZ400 is the predecessor to the YZ426, which is the basis for the YFZ450 motor. The YZ400 motor is easily more powerful than the 400EX motor.

[YZ400EX]

Well the reason why I would use the 400ex frame and not the 250r frame is because I already have a 400ex and everything for one..It is possible to put this motor in the 400ex right?? And will it be worth the money to do it all?? How much would need to be done??

[throwinitup]

easier to put in R frame b/c of the radiator is already all there...your better off goin with a laeger 250r frame and yzf426 motor...this is the most common hybrid, and theyre FAST....but i would only recomend this for a race bike, they rev very quickly..

[YZ400EX]

Well here is the deal..I dont have a 250R nor a frame..I dont have a 426 motor..I have a 400ex and I have a YZ400 motor..I didnt ask what would be the best if I was to build one from scratch, I asked what I would need to do to fit this 400 engine in my EX..Anyone else??

[markk]

I think it would be pretty sweet, u might want to lookup a little bit about the tannys on the yz400 motors, Because if they have problems on a dirtbike, U will forsure have problems trying to turn two wider tires!

I think it would be sweet, and i would say that its posible for sure, just take your time, and think before u start to CUT anything.!

[YZ400EX]

Yea I have tried to find out some info on the motors such as tranny problems or any other known problems and havent seen anything that wasnt caused by unmaintenance (sp) issues..It seems to be a good strong motor from what I have read..I havent picked the bike up yet, but have ridden it and it looks real good and for the price I couldnt beat it no matter what..I dont plan on really cutting anything until I know for sure what I am going to do..I was thinking of picking up another 400ex frame and jst building it all into that and then taking everything off of mine and putting it on once it was all mounted niceley in there..I just dont know where to start really..I need to talk to someone who has built a hybrid and see what they say..I am pretty sure that the 426 uses the same mount setup as the 400 so I would need to know where I can get custom mounts and stuff made to make this all work..

[400exKy1e]

i know u can send ur frame to atv four play and they will make your motor mounts for u for a crf 450.. and i think 426 so if they are the same then u could get it done there www.atvfourplay.com

[YZ400EX]

Actually I just found a good "How to" on the net about this eact conversion..They said special moto mounts can be made and the stock mounts do not need to be moved at all.

[rider250ex]

i would say if you have the extra cash to buy the yz and you are getting a really good deal on it, buy the bike. take out the engine, carb, electrics, etc...sell the rolling chassis. then i would sell your 400ex. with the money from those you could get a nausty 250R rolling chassis with a few good suspension mods. then you would be all set. just my 2 cents

[YZ400EX]

I dont want to do that..I want to keep the 400 I have..I do plan on selling what is left of the bike and then selling my ex motor and electronics and exhaust..I dont want to buy a 250r..I want to make this work with 400ex parts..the 400 in my sig is what I will be using..it already has suspension mods and lot of other things and I dont want to start all over with a 250r..Thanks for the suggestion though

[rider250ex]

thats cool. thats just what i would do. but i can understand that you wanna keep your 400. good luck which ever way you go with it.

[YZ400EX]

Thank you..If I wanted a 250r then I would go that route, but I figure it would be less of a headache for me to just go the route I am taking..Thanks for the replies people..keep em coming

[Chanman420q]

OUTLAWEX did this same conversion yz400 motor in a 400ex frame. He has a hole web site on the conversion. id contact him

[YZ400EX]

I already tried to contact him and am just waitng for a response now..Thanks for the info though..

[ss440ex]

I just got done building two yz426/400ex hybrids.:D
The 426 engine must be shimmed to the left .230
It is .230 shorter then the 400ex.
A rear bushing must be made 2.900 long .095 thicker than
the swing arm/rear eng mount bolt.
Fab and weld two eng mounts cross members,one up top & one below.
Manufacture oil tank,front frame horn mounts,air box,notch out frame left of rear shock mount.
Use a 250r radiator,mfg rad mounts.
Use yz head pipe plus 5 inch ext w/ a 15 deg bend to reach
Sparks x-6.
Yes it is some work, But man what a ride!!!!!!!
I do have several pics, I need e-mail address to send.

[wishmasstir]

www.eastcoastatv.com

they have some parts for your conversion like a kickstart adapter that lengthens the kicker to clear the frame and a carb boot to your airbox

i did this conversion in 99 and had to make everything ... it tore up the 440's no problem on the track

a longer swingarm should also be on your mind cause this motor will make the front end a lot lighter

you can update everything in the motor to the 426 ... not sure on going to the 450 though i think they changed a lot more in it

[YZ400EX]

Originally posted by ss440ex
I just got done building two yz426/400ex hybrids.:D
The 426 engine must be shimmed to the left .230
It is .230 shorter then the 400ex.
A rear bushing must be made 2.900 long .095 thicker than
the swing arm/rear eng mount bolt.
Fab and weld two eng mounts cross members,one up top & one below.
Manufacture oil tank,front frame horn mounts,air box,notch out frame left of rear shock mount.
Use a 250r radiator,mfg rad mounts.
Use yz head pipe plus 5 inch ext w/ a 15 deg bend to reach
Sparks x-6.
Yes it is some work, But man what a ride!!!!!!!
I do have several pics, I need e-mail address to send.

Man I would love to see pics..Can you help through it all as I am going?? Is the YZ400 the same as the 426 size wise like where I would need to file it down?? Send all the pics that you have to woodcand@gmail.com

Thanks

[YZ400EX]

I Thank everyone for all their info..Keep it all coming..

[YZ400EX]

Originally posted by wishmasstir
www.eastcoastatv.com

they have some parts for your conversion like a kickstart adapter that lengthens the kicker to clear the frame and a carb boot to your airbox

i did this conversion in 99 and had to make everything ... it tore up the 440's no problem on the track

a longer swingarm should also be on your mind cause this motor will make the front end a lot lighter

you can update everything in the motor to the 426 ... not sure on going to the 450 though i think they changed a lot more in it

I cannot find anything on the website about the extension or carb boot?? Can you help me out a bit more..Thanks

[panteramatt]

Hey if you want, I have a complete yzf400 motor with carb and all electrical for sale i ngreat shape for only $1000 an dyou wouldnt have to get rid of the rest of your bike which is hard to do caus ethe onlt part that everyone wants is the motor.Let me know.

[wishmasstir]

they have some good products at eastcoatatv
if you contact them they probably have a lot more than that for these conversions or possibly a donar frame for you that already has mounts/modifications done to it ... i'd call them up before you tear into it ... they will actually just do the whole conversion for you

the kicker adapter/extension is at
http://www.eastcoastatv.com/KExtensions.htm

heres the exact conversion your looking for though ... they'll do it all ... make sure you check this page out ... all pics
http://www.eastcoastatv.com/400exyz426conversion.htm

[YZ400EX]

Thanks for the info, but for that price, I think I will just stick to doing the conversion myself..I guess the only thing I will be buying from them is the front motor mounts..

[dork]

the yz400 is the same size physically as the yz426. the trans are pretty tough, although if it has some miles you may want to check the engagement dogs on the upper gears and replace as needed. the 426 uses a bigger clutch with more plates and 1mm bigger wrist pin. you can go to a 95mm piston which will make it a 426 on the stock rod, but reliability goes down because the wrist pin area is a weak spot. best bet is to upgrade to the 426 rod and or whole crank and run the 426 piston. also if you put in a crank, go with a 01-02 426 crank and counterbalancer gear. its mounted with splines instead of a keyway and is a better/stronger design. overall though, the 400 is a strong reliable motor.

[kendog57]

i building a conversion for a friend at the time. as far as the 250r stock use the 400ex chassis for strengh purposes. the biggest thing is mounting the motor , you will need to punch the spaces out of the rear mount and have some new one machined for the . mount the swingarm and mount in and next mount the very front mounts if u buy them next. sure u have room for the carb to clear. i used my 250r rad and mount it just by the back of the oil tank super clean. the biggest problem that every thing is pretty tight fit in the motor so cooling is the biggest thing when u are putting it together make sure it has good flow. mounting it pretty easy. if u need any help let me know because i'm still working on it but will be running at the end of the month or sooning if i have time. i do have some pic i can try to get u if interested.

later
Kendog
Ignition-racing.com

[YZ400EX]

Originally posted by kendog57
i building a conversion for a friend at the time. as far as the 250r stock use the 400ex chassis for strengh purposes. the biggest thing is mounting the motor , you will need to punch the spaces out of the rear mount and have some new one machined for the . mount the swingarm and mount in and next mount the very front mounts if u buy them next. sure u have room for the carb to clear. i used my 250r rad and mount it just by the back of the oil tank super clean. the biggest problem that every thing is pretty tight fit in the motor so cooling is the biggest thing when u are putting it together make sure it has good flow. mounting it pretty easy. if u need any help let me know because i'm still working on it but will be running at the end of the month or sooning if i have time. i do have some pic i can try to get u if interested.

later
Kendog
Ignition-racing.com

I would appreciate any pics that anyone can offer..if anyone has measurements for the upper and lower mounts that would be cool too..My email address is woodcand@gmail.com

[YZ400EX]

anyone else?

[jahaiap]

Originally posted by ss440ex
I just got done building two yz426/400ex hybrids.:D
The 426 engine must be shimmed to the left .230
It is .230 shorter then the 400ex.
A rear bushing must be made 2.900 long .095 thicker than
the swing arm/rear eng mount bolt.
Fab and weld two eng mounts cross members,one up top & one below.
Manufacture oil tank,front frame horn mounts,air box,notch out frame left of rear shock mount.
Use a 250r radiator,mfg rad mounts.
Use yz head pipe plus 5 inch ext w/ a 15 deg bend to reach
Sparks x-6.
Yes it is some work, But man what a ride!!!!!!!
I do have several pics, I need e-mail address to send.
please send pics to jamesinnaples@yahoo.com

[yamahonda]

i don't know any measurements but i have a 400ex with a yz400 motor in it... it was all done when i got it... it was done pretty good but not perfect... i have the block off kit from dr.d to rid the oil tank.. some say it is good some say it is not.. i just change the oil alot... and my radiator is where the oil tank would have been...i can't remember if i checked mine but i read somehwere you have to remove something under the gas tank so head will clear... is there some type of plastics cover under the tank????i can take any close ups you need just let me know what areas... and give me some time to take them cus i have it in storage for winter.. ohh ya it freakin hauls *** too.. here are some pics...
http://predator.bikepics.com/pics/honda-400ex-03-bikepics-218759.jpg http://predator.bikepics.com/pics/honda-400ex-03-bikepics-253628.jpg http://predator.bikepics.com/pics/honda-400ex-03-bikepics-253629.jpg http://predator.bikepics.com/pics/honda-400ex-03-bikepics-270468.jpg
i know i left my dunes tires on the front i just wanted to play in the snow for a few minutes before i put her to bed for the winter..

[YZ400EX]

Man that is a nice looking quad you have there and the conversion looks clean too..I hope mine looks that good when I get it all done..So far everyone of these conversion have been done differently..Its wierd that so many different things can be done to get 1 thing accomplished..I dont think I am going to go with the oil block off kit just because the motor was made to have an oil tank so I figure I dont want to take any chances and just leave it the way it was designed..If you could get me some pics of the bends on your rear slip on part of the exhaust and up to where it meets that header..That would be great..Also if you could get me some pics of how your airboot is run from the carb to the airbox..This seems to be the 2 areas I am kinda confused about still..I am pretty sure that the plastic piece under the tank would have to be removed in order for the motor and carb and all that to fit into place, but thats no big deal. Again Thanks for posting some pics though and again..you have a very nice quad..

[yamahonda]

ok i can get some pipe pics.. but its a tc racing pipe they us a supertrapp and custom make it to fit the titanium header... and as for the air box i can get some pics.. i know mine has a hose on the intake to have the carb away from the mtor a lil bit .. the rear of the carb is basically sitting on the cross over tube acroos the frame... the the boot is on it... which i noticed mine has a crack so i need a used one....

[YZ400EX]

Yea I wont be using that exhaust, but just want to get a general idea of what kind of bends I will need to get to make it work..Your carb sounds like it may be setup differently than I wan to go as well, but would still love to see pics to see if I do want to go that route or not..I appreciate your quick responses as well..

[yamahonda]

http://www.angelfire.com/ny5/dopeblaster/project2.html go here i was looking at this as we speak to see the diff....

[YZ400EX]

Yea I have been speaking with this guy alot about this conversion..Very nice guy I might add..His is super clean and he did everything in my opinion almost perfect..I just dont quite have the money to spend on some of the parts he did..I also found another member of exriders to buy all the mounts from for a very good price I think..

[yamahonda]

yeah his conversion looks awesome.... mines ok and gets the job done but that one is good .. i am thinking of changing some of my stuff is why i been looking at diff setups..

[YZ400EX]

yea I just want to get this one done..After I get it all done I will start spending more money on it like radiator and so on, but just want to get it out and running first of all..

[yamahonda]

you know any other websites with info?

[YZ400EX]

I dont..His is the only one I could find on this conversion..Sorry..

[yamahonda]

yeah i been thinking of adding a oil cooler... the block off kit is good and makes it lighter.. but i'm not an all out racer so i was looking at maybe adding the cooler and moving my radiator.. but if i do what outlawex did .. my radiator could stay were it is... i also wanna pc the frame and stuff and if i do i will gussett it more and maybe cut out the frame for the carb tube..if i need to ..it works fine like it is thou... i also been looking at getting diff exhaust so when i'm racing or duning i can run the tc but when i'm trail riding with freinds and stuff put on something not as loud cus tc is very loud and they don't like to ride around me...

[panteramatt]

Hey 440, if I were you I would leave the oil tank cause those engines run very HOT and the oil breaks down faster than any other bike Ive seen. I have a 250r with one in it and mine has the 400ex oil tank and cooler on it.

[YZ400EX]

Yea I will definately be leaving the oil tank on it..Now does the oil cooler have to be on there too?? If so this is the first I have heard about it..

[yamahonda]

Originally posted by 440EXGUY
Yea I will definately be leaving the oil tank on it..Now does the oil cooler have to be on there too?? If so this is the first I have heard about it.. what are you saying????? your leaving it on but don't know why????

[yamahonda]

this is from dr d website... not saying it is good or not but i got it.. and could dr.d be wrong???? the block off kit
Wet Sump Kit (top)


Wet Sump Kit Features
Replaces neutral switch
Eliminates oil in frame
Less oil capacity means less weight
Clear site window allows you to view current condition of oil
Gives a cleaner appearance to the left side of the engine
Installs in minutes


Available models:

#5006 fits 01''-02'' YZ/WR 250f

#5007 fits 03''-05'' YZ/WR 250f

#5008 fits 98''-02'' YZ/WR 400/426


Price
$150.00

[YZ400EX]

Originally posted by yamahonda
what are you saying????? your leaving it on but don't know why????

What I am saying is that I have not heard of anyone leaving on the actual oil cooler! Maybe it was something that was just was not mentioned or is not needed on this conversion. Is this something that needs to be on and wasnt mentioned or is the oil cooler from the 400ex no longer needed?

P.S what is Dr. D's website address??

[panteramatt]

No, you do not need the oil cooler.I dont have it on mine and it would just be a pain to fit it but if you have the room and it will work than use it but not a big deal.

[yamahonda]

dr.d =www.dubachracing.com

[416exmx]

here are a few of a YZ/EX conversion i used to have...
Mine used a Custom oil tank in the form of an L shape. You can get them at ECA.

[416exmx]

another

[416exmx]

mine used a YZ headpipe and TC silencer. An adapter was made to connect the two.

[416exmx]

...

[416exmx]

i also had a 9oz. flywheel weight on this one. I will thell you that the YZ's will wear you out alot faster than your ex will..

[YZ400EX]

Thanks for all the pics...Those look really nice..That is the kind of oil tank I wanna use..It seems to be the best..How much was it??

[QuAdEr 317]

Originally posted by 440EXGUY
Yea I have been speaking with this guy alot about this conversion..Very nice guy I might add..His is super clean and he did everything in my opinion almost perfect..I just dont quite have the money to spend on some of the parts he did..I also found another member of exriders to buy all the mounts from for a very good price I think..

are you saying you could buy mtoor mounts that you dont have to weld in? and lik you buy everything as a package? or what? n for what motors

[YZ400EX]

The upper and lower motor mounts would need to be welded onto the frame and the front mounts need to be drilled. As far as I know they would be for the YZ400 or 426 motors into a 400ex frame.

[YZ400EX]

I cannot find anything on Dr. D's website about the oil block off kit..Does anyone know if someone makes a custom exhaust for this particular conversion?

[yamahonda]

its called a wet sump on dr.d website.... and as for exhaust i know tcracing makes some but they are pricey for them just to make a supertrapp fit a yz400 header....

[YZ400EX]

As far as the exhaust goes I hate the supertrapp style exhausts anyways so I would never go that route..I guess I will be looking into getting a Curtis Sparks X-6

[Chanman420q]

this thread got big since i first posted.

ok well i got some input and im also looking for answers.

i wouldnt take what i say to strongly as i have no experience with doing these conversions so i prolly shouldnt say anything, an on top of that im sure it was already mentioned. but what the heck cant hurt

From my understanding, the 400,426, and 450 all have the same motor mounts. i know the 400 and 426 do. not 100% on the 450

from what ive read and word of mouth ( again not always facts so dont flame me or anything like that ) the 400 and 426 have similiar power, the 426 is a bit snappier, but i heard that it did have minor clutch and tranny problems that the 400 didnt have.

Also, id suggest running an aftermarket radiator. From what ive read the 250r radiator isnt exactly the best at keeping these beasts at a good opperating tempature. But its also the cheapest route.

As far as the air boot, i saw someone use that like adjustable heating tube. the stuff that moves around. Like the tubes you see with dryers. that kinda stuff. Thats the best way ive seen to do it without cutting into the frame.

ive also pondered doing a conversion. Not because i want the power ( altho i wouldnt mind it ) but basicly because i like a project. Like many people my ex is pretty done up. an again like many people, especially at my age, dont have the money and dont want to take a loss at selling the ex. Face it the ex has no value diffrance between being a full race ready to completely stock. in everyone;s eyes a 400ex is still a 400ex.

How much money are we looking at to get a YZ motor into a 400ex frame? Besides the motor, ruffly 1000-2000 dollars, how much more is it gunna cost to get it up and running?

and if u read this entire post, props to you because i woulda read the first sentance and moved on:)

[YZ400EX]

hey I read the whole thing..hahaha..anyways man I am in the same boat as you with this conversion, but as said before I got a very good deal on an entire bike so it is an opportunity I cannot pass up..Motors I would guess would run around $1000-$1500..I have also heard of problems with trannies on the 426 compared to the 400 so I think I will be happy with this conversion..as far as the radiator goes I am sure that an aftermarket radiator would be better, but for now I will have to use the stock 250R rad until I can get enough money to upgrade..I do not have alot of money to work with from the start..I will figure something otu for the airboot..I have seen a few ideas out there and am sure I can come up with something..As you said..the 400ex is a 400ex no matter what is done..around here nobody really cares what all is done..They are very expensive around here though compared to what others can sell theirs for on this site. I mean $1800 for a 400ex here is unheard of, but on this site is somewhat common..The main reason for doing this converion is because I have yet to see ANY hyrbrid quad around here and I want to be different than everyone else..To make a long story short I believe w/out the cost of the motor you can finish the rest w/around $800 at most..Thats what I am guessing..I already have my motor, frame and full exhaust soldto someone to help me offset almost all of the costs..I am doing this to be different and for something to do..I love projects..I am doing a 300ex right now, just finished a 250x to 350x and after this conversion we are going to put an XR 500 motor into a 250X frame..man this was a long post!!!:D

[Chanman420q]

i know around here the 400ex are still listed at a good ammount of green, but there also isnt to many "race" ready quads either. But who knows if there selling.

[racerx573]

Yamahonda, where'd you get the short kicker??

[yamahonda]

Originally posted by racerx573
Yamahonda, where'd you get the short kicker?? it was on it when i got it....



and to the other guys.... when i got this quad i was looking for a project... it is already done but needs few touch up things.. so most of the hard stuff is done now its my turn to clean it up and make it look even better...... as for power this thing will run and run good... i have rode 400exs ,banshee's and this thing flys... my brother has a banshee with just pipes and k&N's and he is no match.. but i hook up he spins alot... i'll be glad hear in a month or so i'll be heading to the dunes and that whn i will really be able to tell how it really runs... all my freinds have banshee's!!!lol

[YZ400EX]

I cant wait to get mine done and see how good it runs against my friends Trinity built DVX 440..I dont stand a chance right now..It is just wierd that a motor with the same cc's (400ex, YZ400) can be so much different..I was told that this 400 will dominate his 440, but who knows..only time will tell..I just cant wait to get it all done and find out...:devil: This motor is supposed to have some stuff done to it as well like port and polished, but dont know for sure..

[416exmx]

The best thing to do for the airboot setup is go to an auto parts store and get like a radiator hose that is already bent right for the application. Also, i used a 250r radiator on my 426 quad and never had any problems. I wouldnt want to let it set around and run for several minutes, but get moving and you will be ok. Something else to think about it the shocks. I know when i was building the CRF quads that they were about 25-30 lbs lighter than the 400ex. Therefore your suspension will be a little rough because you quad is lighter. I had a set of shocks valved for me and after i did the conversion i could tell a difference.

I had the YZ quad pictured earlier, and also have had 3 CRF quads. I can tell you that i liked the CRF's a TON better. The YZ's have a harder hit and feel like you have more power, but the CRF's are a little more mellow and actualy have more usefull power. I had a 9oz. (i think) flywheel weight on my YZ to help mellow it out and also to aid in stalling in the corners. Oh yeah, these are real touchy and if you just tap the rear brake without the clutch pulled, and you'll kill it. Then try to start it after you stall it during a race. A thousand things are going through your head and the last thing you think about is the procedure to start this thing (pull decompression, find tdc, go one click past, release decompression, kick it, ((hope it dont kick back )) and if your lucky it will start, if not the go though it again. ANYWAY, not to discourage anyone from this conversion but i really HATED my YZ. The CRF's were a breese to start, they ALWAYS started, produced good power (one even had a flywheel weight), also the biggie was it was a HONDA lol.. Really though, there isnt much price difference between price on the YZ motor and CRF motors anymore. Whatever you guys build you will have a BLAST building it if you are into stuff like that.

[ss440ex]

For around $100.00 You can install a decompression exhaust cam.
Thats installing it your self!
And that will do way with the decomp lever and the kicking procedure.
You are correct on the wieght differance with the shocks..
But thats a plus!!

[YZ400EX]

So whats the deal on the starting procedure?? I dont understand why it would be so difficult compared to any other kickstart engine..why would there be so much work to get it to start?? I have just never heard of it before??Now about the CRF or YZ quads..I would rather have a CRF quad to a YZ quad any day mostly because I am a Honda guy, but I already have the YZ motor and I got it for a steal which I need to use because I do not have a CRF engine, but I wish I did. I am pretty sure I will be plenty happy with the conversion that I am doing even if it isnt as fast or comparable to the CRF..As far as the shocks go, That would be cool if it lightened my quad up a big and stiffened my shocks a little..Right now I feel they may be just a bit too soft..It will be a blast to build, a good experience and I hope it looks good when I am done.. Please let me know more about this whole "starting procedure"..Is it the same on the bike??

[416exmx]

Originally posted by 440EXGUY
So whats the deal on the starting procedure?? I dont understand why it would be so difficult compared to any other kickstart engine..why would there be so much work to get it to start?? I have just never heard of it before??Now about the CRF or YZ quads..I would rather have a CRF quad to a YZ quad any day mostly because I am a Honda guy, but I already have the YZ motor and I got it for a steal which I need to use because I do not have a CRF engine, but I wish I did. I am pretty sure I will be plenty happy with the conversion that I am doing even if it isnt as fast or comparable to the CRF..As far as the shocks go, That would be cool if it lightened my quad up a big and stiffened my shocks a little..Right now I feel they may be just a bit too soft..It will be a blast to build, a good experience and I hope it looks good when I am done.. Please let me know more about this whole "starting procedure"..Is it the same on the bike??


yeah it is the same on anything with a manual decompression. Try to jump on it and just kick it over... haha, you'll jump and jump and may break the kick start lever before you start it. I have a YZ250F motorcycle and it is the same way even on a 250cc. ... Like i said it is kinda a hard thing to get used to but once you get it down, it is not to bad, just kinda hard to do when you stall it in the cornor during a race. I however never stalled mine during a race but did many many times before i understood what to and what not to do. It will take a bit to get used to but when you get the hang of it, you will LOVE it. Also like i said, these will wear you out faster then the EX will. And yes you can put a cam in with auto decompression but i have not had experience with one so cant help you there.

[yamahonda]

to start its hard at first but once you get a hang of it its easy... you have to get kicker to top... then tap the decompression lever and give it hell each time... the main part is getting it to the top and do not give it gas unless you want a broken foot...

[YZ400EX]

So is this method only needed after it is warm or is it needed anytime you are going to start it cold or hot?? I have never heard heard of this method and have had alot of engine with decompression levers on them..Also when you use the decompression lever is it held all the way in or just partially?? All this does is open one of the exhaust vales right?? If you hold it all the way open does the valve hit the piston?? I am interested in finding out more on this..Thanks

[yamahonda]

well mine it works hot or cold .. depends how you shut it off hot.. as in if you kill it sometimes it takes alot of kicks sometimes one kick... but as for pressing the decompression.. it hard to explain.. you wanna get it o the top pull the decompression lever in and let off then move kicker to next hard spot and kick hard to ecplain but you will see whn you try it..... but don't hold it in .. you will feel it when you have it to the top and press on the kicker and pull the decom lever and let off ...when i got my bike they guy said it wasa the hardest thing was learning the kick start method but i aced it after 3 kicks and have no problems... if you have had to compression motors i'm sure it will not be a problem....... i know i race once a yr and if i kill it i'm done cus by time i get my big 400 running race will be over... its little track and only 4 laps...thats if its starts on first kick...

[YZ400EX]

That sure is interesting..I have just never heard of it all before..I guess I will soon figure it all out or just get the decompression cam to make my life easier..Now does anyone know what the weight difference would be between the YZ400 and the 400EX engine?? Just wondering