is this class legal by ATVA Rules?

[JHF219]

just curious
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=2485894717&category=6725

[ReconRider25]

i dont see why it wouldnt be...

[Guy400]

I don't keep up with the Yammy's all that closely but why take a YFZ, remove the 450 powerplant and replace it with the 426? I thought they were the same engine save the cam timing and displacement?

[Toadz400]

Originally posted by Guy400
I don't keep up with the Yammy's all that closely but why take a YFZ, remove the 450 powerplant and replace it with the 426? I thought they were the same engine save the cam timing and displacement?

Right now all I can figure out is because it's probably quicker revving because of the shorter skirt (aren't they shorter on the dirtbike?), titanium valves, and the stuff you listed...or it was all for sh*ts and giggles?

[bradley300]

Originally posted by Guy400
I don't keep up with the Yammy's all that closely but why take a YFZ, remove the 450 powerplant and replace it with the 426? I thought they were the same engine save the cam timing and displacement?

the yfz quad uses the electric start 5 speed WR motor*(thats right, its not the yz-f motor everyone thinks)

the 426 is the yz (mx) motor, no eletric start, and a harder hit than the wr motor, and i think its a 6 speed also

[JHF219]

Originally posted by bradley300
the yfz quad uses the electric start 5 speed WR motor*(thats right, its not the yz-f motor everyone thinks)

the 426 is the yz (mx) motor, no eletric start, and a harder hit than the wr motor, and i think its a 6 speed also

the 426 is a 5 speed manual start the new yz450(bike) is a 4 speed im wondering about swapping the motor would that still be atva legal? i mean its still a stock chassis and all.

Im thinking that when i buy my YFZ im going to buy up a head off the motocrosser(bike) and install it. the head is what makes the big difference. so in turn i would think it would be a MUCH harder snapping 450

[Cody_300ex]

I thought the motor cases have to mach the frame??:confused:

[bradley300]

Originally posted by Lil_300Ex_Kid
I thought the motor cases have to mach the frame??:confused:

they do, the cases must be from the same model as the frame, for instance, it dosent have to be the original motor, but if its a yfz frame, it has to be a yfz motor. not a wr or yzf. in all honestly tho, swapping the yfz motor for the wr motor would be a waste of time, all you will gain is a cam sprocket on set on a different tooth, wich can be done to the yfz motor anyway. you could get by w/ that swap tho, theres not any outside appearance difference.
the yzf into yfz would be totally illegal tho, any tech inspection can clearly see there isa kicker and no spot for an electric start

[Out_Sider]

Originally posted by bradley300
they do, the cases must be from the same model as the frame, for instance, it dosent have to be the original motor, but if its a yfz frame, it has to be a yfz motor. not a wr or yzf. in all honestly tho, swapping the yfz motor for the wr motor would be a waste of time, all you will gain is a cam sprocket on set on a different tooth, wich can be done to the yfz motor anyway. you could get by w/ that swap tho, theres not any outside appearance difference.
the yzf into yfz would be totally illegal tho, any tech inspection can clearly see there isa kicker and no spot for an electric start

what about those yfz owners that removed all the electric start components and put a kick start on it? what difference could they tell

[bradley300]

Originally posted by Out_Sider
what about those yfz owners that removed all the electric start components and put a kick start on it? what difference could they tell

i THINK the tzf cases are differemt than the WR, for the sheer fact that the yzf doesnt have electric start, so it has different cases that dont have a spot for it. could be wrong, but i think thats the case

[TGW_400ex]

lets take a engine out and put a dirtbike engine in it that gives no pwer gain and makes your fingers go numb after 5 mins riding it

[SRH]

the yfz is not wr and not yz , the timing is wr with cam mod is yz, the yfz puts out more hp than a 426 motor... yes the wr and yfz have electric start but there not the same motor....

[SRH]

Originally posted by Out_Sider
what about those yfz owners that removed all the electric start components and put a kick start on it? what difference could they tell

u cant remove the battery with the yfz u need it to complete the loop, or u can get the thing from trail tech that replaces the battery

[TGW_400ex]

Originally posted by SRH
u cant remove the battery with the yfz u need it to complete the loop, or u can get the thing from trail tech that replaces the battery

can't you just hook the terminals together?

[ramp rida 55]

i think it would be cool to have that 4-spd trany form the new yzf a 4 spd is a good idea you could keep it in 3rd the whole track

[mxdave28]

you CAN run this type of set up in ATVA classes.....just not any production classes or the Pro classes.....

this paticular set up you can run the 265 abc....4 stroke abc classes without any troubles. cases do not need to match the frame if you run these classes...now if you run any production classes the yes they DO have to match

[cmezo]

the motors do have some appearance diffs other than the elec start mounts the sides of the cylinder where it bolts to the head go into a point on the yfz and are rounded on the yzf. but i agree leagal for racing all but the production classes

[5valves]

Originally posted by JHForman250R
the 426 is a 5 speed manual start the new yz450(bike) is a 4 speed im wondering about swapping the motor would that still be atva legal? i mean its still a stock chassis and all.

Im thinking that when i buy my YFZ im going to buy up a head off the motocrosser(bike) and install it. the head is what makes the big difference. so in turn i would think it would be a MUCH harder snapping 450

I was thinking the heads were the same. I thought the lower end was diffrent, (crank)
Thanks why the 04`s still have the decomp plug.