Difference between dt,it,yz,mx yamaha's?

[dirtbikedan]

I sure like my '78 dt175, but was wondering where the differences lie among them. I had never heard of a mx175 until recently on this forum. From what I've gathered, the dt was a street legal machine, the it was an enduro (although my dt has enduro175 decals on it) and the yz was of course the mx'r. Can someone clarify these, I'm really obsessed with these late 70's yamaha 175's, I have three and I feel the need for more. lol

 

[Psyco Diver 69]

DTs were built to go off road and go on the street. The MXs were built for offroad and have a more "tuned" engine and stiffer suspension. DTs were tuned for more street ablity and has nice lowend power and the MXs are tuned for more offroad and were tuned for topend power, the DT175 makes 22hp while the MX makes 27hp. I great upgrade for the DTs is to get a MX pipe off of a MX around the same year, it will free up a good amount of power from what I heard.

Now on to stuff I don't know, the YZ is a motocross bike and I don't know what the IT was, I heard they were detuned version of the YZ with softer suspension.

 

[dirtbikedan]

That's interesting. Anyone know what engine parts are different among each one? Porting? carb?

 

[OnAnySunday]

DT was the dual-purpose bike. (street-trail)
MX was the offroad playbike. (basically a DT wo lights.)
YZ was the motocross/competition model.
IT was the serious offroad bike. (ie: enduro race.)

Not sure why the DTs coined the phrase "enduro".
Maybey cuz they were in production before the ITs were.
My generation reffered to dual purpose bikes as "enduros" ever since. :)

 

[dirtbikedan]

Thanks guys, I was just curious. Mine has the lights stripped off. Like that when I got it. I also milled the head down, and a few other small things, and I enjoy the heck out of it! As well as my '99kdx200

 

[rmxr]

Actually the MX and YZ bikes were both motocross bikes in the early 70's.
The 'enduro' street legal 175 was a CT175.
The YZ's were supposedly limited production, had the gas tank strap, finned shocks, ect. The MX models were slightly less expensive, less skill riders raced these, raced against many back in the day. Kinda like a Combat Wombat vs a Super Combat Wombat, remember those?

 

[OnAnySunday]

Originally posted by rmxr :
"Actually the MX and YZ bikes were both motocross bikes in the early 70's.
The 'enduro' street legal 175 was a CT175."

Whoops! Forgot we were talking about 175's. :confused:
CT is correct, although (and i am probably wrong.) didnt Yamaha eventually designate all their dual-purpose bikes as "DT's"???
And some people may have raced the "MX" Yamy's, but they were pretty much considered Yamaha's version of the XR line.
(even though they burned oil.)
More play than racebike.
Also maybey the first year or 2 YZ's may have been limited production.
But after that i thought they were as easy to get as Honda's Elsinore.
(well mebbe THAT explains it.) :confused:

 

[Psyco Diver 69]

I don't think so, the MXs made more power while the DTs made more torque. The MXs were 11lbs lighter and also had stiffer suspension than the DTs. I can rip by most any modern 1225 with ease and all thats done to my bike is its bored .060 over, its slightly ported (mostly cleaning up the ports after the last rebuild) and my bike wieghs 210lbs full of gas and oil.

I stripped the whole oil injection system off, the whole headlight assembly, tail light assembly, metal fender that goes under the plastic fender, whole YZ wheels (way better brakes and alot lighter) and I have no air box (the pod filter makes more power but its a pain in the ass when it rains or if I'm riding in a lot of mud).

 

[rmxr]

My response was from my 'Way Back' machine. the original Yamaha motocross models were called MX(fill in the engine size), this was before there were any YZ models. When YZ models came out they continued to make the MX, it may have evolved into a more of a play bike as they did not evolve aong with the YZ line. Actually before the 'MX' line they had MX after the name, aka AT-1 MX, DT-1MX, ect. Before that no MX models at all, you bought your 'enduro', stripped it, and put on the GYT kit. No silencers back then, none, those starting lines were Loud. I'm not a Yamaha expert but I raced late 60's early 70's nd this is what I recall, don't take it as gospel. Yes, later all Yammie enduros were called DT but by then the were fairly dated.

 

[dirtbikedan]

Anyone heard of a "tt"?

 

[dirt bike dave]

TT is Yamaha's designation for 4 stroke trail bikes. XT is a four stroke dual purpose bike. I don't think there was ever a TT or XT 175.

I think the YZ175 of the mid '70s was identical to the YZ125 except for the engine.

 

[dirtbikedan]

Thanks guys!

 

[BadgerMan]

Rmxr,

You are right. The MX and YZ coexisted as Yamaha's motocross line for three or four years ('73 through '76?) I think. They only sold a 125 model in 1976 which was the MX125C and it had the rear shocks laid down whereas all the YZ's were mono's.

I remember the MX models as being pretty capable race bikes. I think '75 was the last year for the MX175 and it had a white with blue tank and white fenders. The MX250 and MX400 had mono's that year but the smaller bikes (100, 125, 175) had thermal flows.

I think they "reintroduced" the MX designation later on (late '70's or early 80's) but they were just a stripped down dual-purpose bike.

It's hard to believe that any old MX Yamaha (except the 360/400) would run with a modern 125. All those bikes were slow by today's standards.

TT's you ask? Just saw a '78 TT500 for sale. Excellent condition, $500.00. I Wish I had room in the garage!

 

[Psyco Diver 69]

Originally posted by BadgerMan
It's hard to believe that any old MX Yamaha (except the 360/400) would run with a modern 125. All those bikes were slow by today's standards.

Heh you havn't seen my bike yet. I can get wheelies started in 4th gear (5th gear too if I hit a bump). Its got alot of mid range, it would have a lot of top end but I need to get a bigger carb for that. I'm also thinking about sending my cylinder away to get it ported (its the only engine mod I have left to do). I like the mid range though, its works good in the trails. Theres not a person in this area that can keep up with me in the trails either, my main problem though is braking (I have drum brakes) and I seem to mess up on what gear I should be coming out of the corner with, but thats for the technique forum.

 

[WoodsRider]

IT stood for International Trials. The bike was originally designed for the International Six-Day Trials (ISDT) which was renamed the ISDE in 1980. The bike originally came with a 400cc displacement but eventually came in displacements of 125, 175, 200, 250, 425, 465 and 490.

The DT models were called Enduro for marketing purposes in the U.S. Basically the first DT-1's were stripped down and ridden at U.S. enduros. Keep in mind in most enduro bikes have to be street-legal. Now we try and make our off-road bikes street-legal, but in the old-days they turned street bikes into off-road bikes. The DT-1 was originally the first dual-sport bike mass-marketed in the U.S., but everyone called them enduro bikes and the name stuck.

 

[Enduro_Nut]

My first bike was the 1970(1?)JT1 MX(60CC), basically a bike w/no lights,etc and front number plates - no difference in performance though, just lighter as WoodsRider mentioned. The next bike was a 75/6(?) YZ100 which was considerably better than the mx. In 76' bought a DT400(still have it) for piddling. But the previous post is right - for the most part the mx was a stripped ct/dt model.
It's unfortunate that the light weight 2 stroke middle class bikes are gone. They were reliable and lighter than the thumper counterpart. They were great "starter" bikes

 

[Offroadr]

Don't forget the SC

 

[Enduro_Nut]

How many years did they produce the SC - one or two? They seemed very rare, or maybe I was in the wrong place/wrong time.

 

[rmxr]

I think they made the SC500 around 1973, they were awful, Yamahas version of an early TM 400 Suzuki.

 

[Offroadr]

1973 and 1974 I have a complete 74 and a parts bike 73

 

[NYkdxer]

I have a '75 DT-250 that I just got running. It's a lot faster than I thought it would be. How much HP did these make?

 

[agitt73]

them there IT yama haulers were more less an air cooled kdx
and performed very well one in good shape would stick with any modern kdx
they were great bikes but on the flip side dont forget the LT models
i had 2 twin purple 100's with a nike stripe on the tanks plus one mx
model of them that was silver

 

[OldnDirty]

All of your collective info regarding the relationship between the early DT, IT, MX and YZ is pretty much spot on. However, you haven’t discussed the effect of gearbox ratios and generator choice on the characteristics of the bikes.

There are a lot of interchangeable parts between the AT, CT, IT, MX and YZ 125/175 and the DT, RT, IT, MX, SC AND YZ 250’s, 360’s and 500. I wont go out on a limb and say this as an absolute but I fairly sure that you’ll find that with the AT/CT and the DT/RT you’ll find that the gearbox interchange and that the centre three gears ratios are identical for both the close ration gear boxes (MX and YZ’s) and the wide ratio gearboxes (DT and IT’s, and even the TY). On the wide ratio gearbox 1st was generally lower and 5th generally higher (the TY had an even greater step). Additionally there were overall gear ratio variation between the close ratio and wide ratio gearing with variation of the chain sprocket ratios. DT and IT’s used the same wide ratio gearbox but the IT’s were gear lower with smaller front sprockets and/or larger rears.

This info can give you a wider choice of replacement parts if you are doing a restoration/rebuild or give you the opportunity to make a very useful special if you have one of these.

Ditto the choice of electrical generator. The IT’s, MX’s and YZ’s run CDI’s with a very light flywheel. These engines revved freely picking up and losing revs quickly. This made for instant power and good acceleration, and uncontrolled wheel spin in slippery conditions. The trail bikes, DT’s etc, run a flywheel magneto. These magnetos slowed down the revvability of the motor; they made the engine more tractable. The flywheel mags and the CDI’s interchange. The bottom line is that if you put the barrel, head, carby and exhaust of an MX on to a DT you get and exceptionally useful and improved DT. The MX's/YZ's power and the DT's tractability. Try it and you’ll wonder why Yamaha didn’t do it themselves. You can play mix and match with many of the other parts as well. Even from race to race as condition change.

Ditto the SC. Replace the 4 speed SC box with the DT/RT or MX 5 speed box and run a flywheel mag and it will transform the SC. And again you’ll wonder why Yamaha didn’t do it.

Cheers, OldnDirty.

 

[agitt73]

the yamaha blaster atv has the IT 200 engine

 

[mattwr250f]

I own both a 81MX175 and a 81IT465. The guy I bought em from only ran them for one summer and then him and his son lost interest and never road them again. Took a bunch of carb work to get that IT going but its a dog in the woods. Not to many guys can keep up with me in the woods. And as for that MX175 its just a fun little bike to run around on.