i am going to start another thread on dt it yz 400 ..
btw you sir should ty cleaning your baffles and checking either your jets or adjust your metering rods clip osetting on the carb it should wheelie the dts mufflers block up pretty bad my dt260 didnt wheelie till i reset the metering rod all the way up
my dt400 will whellie in all 5 gears its geared too low has a kx250 back wheel on it soon to be back to stock , just winding out the gears it lifts the front tire
ok now i own a few . i am building a it 400 . i own like um 3 it 400 bottom ends , 3 dt400 bottom ends 2 yz 400.s 1 it 490 2 yz 490s , 5 dt 360s /. a few 250's ...
the mx dt ports are smaller and have les duration then the it yz
the 77 78 bothe have the clutch cable mounted to the lower end of jug . wich isnot cast in 76 and earlier models the 79 uses a diff stroke conn rod etc
a mx400 stock is 28hp on the rear wheel thats bone stock and not at the crank
bhp , all uamaha 400 have cdi
ok difference between the dt/mx 400 75 to 78 and it 400 76 to 78 the engine is the piston and connecting rod . the cylinder also also different .but you can swap one for another just use the right piston for the rod you have the connecting rod on the dt and mx is number 498 , the rod on the it and yz to 78 is 214 . the 214 rod was used on all 70's dt 250's it yz 250's . rt360's dt360's and it yz 400's
the piston is about 4mm longer on the dt/mx 400 then the it/yz
i just was working on this tonight its an it 400 with a dt400 jug and a dt400 piston
what is nice is the yz 490 piston wich is 87 to 89 mm will work on a dt400 crank and rod . if you want to use it on a ityz 400 you need to either install a dt crank or a dt rod you also have to modify the pistons skirt for clearance
the shorter rod makes more torque at low revs because of the rod angle on wich it has , acts as leverage on the crankshaft but wastes inertia because of preload transferring energy at the cylinder walls resulting in drag on upper rpm levels
were as the longer rod doesnt and actually has better volumetric efficiancy because the piston dwells at top dead center longer , and will excellarate quicker at higher rpms
i actuallly was quoted by somebody on that above and it ended up as an article in like phr as readers blogs way back when i was at summer carlighle dennis gades was walking around filming for hotrod tv that day must a been like 96 or 97 the 79 it and yz 400 like i said have a different stroke and have thier own part number for the rod as 2x5
yeah i kinda am figuring yamaha out step by step
personally i want a blaster with a dt400 on it to rip around on ..