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

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Posted by: 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


Posted by: 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.


Posted by: dirtbikedan

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


Posted by: 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.


Posted by: 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


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.
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?


Posted by: OnAnySunday

[QUOTE]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:


Posted by: 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).


Posted by: 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.


Posted by: dirtbikedan

Anyone heard of a "tt"?


Posted by: 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.


Posted by: dirtbikedan

Thanks guys!


Posted by: 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!


Posted by: Psyco Diver 69

Quote:
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.


Posted by: 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.


Posted by: 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


Posted by: Offroadr

Don't forget the SC


Posted by: 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.


Posted by: rmxr

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


Posted by: Offroadr

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


Posted by: 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?


Posted by: 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


Posted by: 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.


Posted by: agitt73

the yamaha blaster atv has the IT 200 engine


Posted by: 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.


Posted by: Psyco Diver 69

Quote:
Originally posted by 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.


I've owned my 81 MX175 for 4 or 5 years now and I'm one of the fastest around here. Of course I did work on the motor a little, plus I dropped the gearing down so it will move a lot quicker, but I post top end speed, but no big deal I never used it that much anyways


Posted by: mattwr250f

driver69

Does your 175 have one heck of a stump pullin first. I'm not sure if mine was regeared inside or not, sprokects are stock. But it seems that unless I have one heck of a hill to climb or I'm really really luggin it I dont hardly even use first-start out in 2nd most of the time.

Is yours similar to this


Posted by: Psyco Diver 69

nope, I can barely use 1st because it whineds out really fast. I'll say though I never got stuck in mud with my bike but she does get loopy on hills or she'll get stuck on sand hills.


Posted by: CanAm1

Rare bikes if you can find them when I lived in Springfeild Mo the Yamaha dealer who was also a Penton KTM dealer.They had twin shock laid down shock MX125s and 175s that came with a YZ engines this was the only I have ever seen them.They may have been euro-market bikes they where white tanked with blue 125 red 175 stripe.Back then I ran a 73 125DT witha 75 YZ GYT kit the kit made so much power it smoked the trans.


Posted by: tjg

I started out riding in 1976 with a new holdover 74 MX360 ( 1st year for yellow and black paint ) I was 16 and Dad thought the 360 looked like a better bike than the 74 MX 175. BTW he never rode a bike. Several neighbors had dirt bikes ( Honda CR Bultaco Pursang, DT Yamaha, even a Rickman). The 360 was a handfull to ride to say the least. Forks and frame flex, all or nothing powerband. Don't remember getting beat in a drag race though. Bought a new 77 YZ400 in 1978 and discovered the joy of long travel suspension. Rode trail and a little mx and a lot of shorttrack. Shorttrack bikes would outcorner but couldn't outrun on the straitaways. Sold that and got a new YZ400 in 1979. WAY better than the 77 and light years from the old 360. My buddies bought TT500 4 strokes ,put in big carbs, cams, supertrapp silencers TONS of head and piston work and then they could keep up to a stock YZ. I'm sure modern 250 mx bikes would get a run for their money on those late 70's YZ 400's. My 2 boys race now on a KX125 and a YZ450. the older one had a 81 IT125 and he loved it. He rode that before he started racing and talks of finding another for a fun bike. Sorry about rambling on like this just remembering my flaming youth fondly.


Posted by: dcropsey

New here, looking for an answer. I have a 1975 yamaha dt125 enduro. In researching, it appears there may have been several variations. Example dt125a, dt125b, dt125c, etc., all put out in 1975. I do not know which mine is as no manual came with it. Any easy way to tell just which it is, or even what the a,b,c stand for. Thanks from the rookie.


Posted by: fatcat216

Engine numbers is one possibility.

http://dirtbike.off-road.com/dirtbi...l.jsp?id=331920

http://www.yamahaclub.com/forums/in...?showtopic=8123


Posted by: TRexRacing

Yep.yamaha's answer to the XR Hondas.


Posted by: kschilk

The year the bike is manufactured, is not necessarily the same as the "model year". The "A, B, or C" after the "model", designates '74, '75, and '76 respectively (for Yamaha). As I understand it, for example....a DT125C would be a 1974 model, mfg'd. in 1976....basically unchanged from the '74 model but the "C", would denote the minor differences like paint, graphics and/or minor aesthetic or mechanical updates.


Posted by: dcropsey

Thanks to all!


Posted by: Vintagesplash

Quite an old thread, resurrected.

The MX line was the common man's motocrosser, and the YZ started out as limited. In 1975 Yamaha made a 80, 100, 125, 175, 250 and 400. This was the last year of the full line. In '76 the YZ250 and 400 were essentially the same bike as the '75 MX models, they even have the same engine and frame numbers. The main differences are the air chambers on the forks of the YZ and the swingarm top brace being rectangular on the '75 and round on the '76.

In 1977 I destroyed my knee while racing my CR125, and while recuperating, bought a '74 MX250 to trail ride. I found the bike to be quite peaky for a 250, but enjoyed it anyway. After healing, I bought a new CR250R, but kept the Yamaha.

I still have the Yamaha. In 1984 when I went into Navy bootcamp, I placed the Yamaha in my fathers barn and promptly forgot about it.

In 2000, I joined AHRMA and pulled the '74 from the barn. Cleaned the carb, put new pre-mix in, and a new plug, and it started on the 3rd kick.

A few months later the ignition went out so I put a PVL on it, then took it to B&J Racing for a 1st overbore and port job.

Now this bike runs like a scalded cat. I rode it today, along with my fully modded KDX200, and the MX is much faster on smooth ground.

The MX's were raced professionally even through the '75 season in AMA competition.


Posted by: pgkeating

I had a '76 YZ250-First year of the mono-shock. Not sure how the frame/swing arm fitment of the (YZ) mono vs. (MX) twin shock went, but I have to believe they were (vastly) different. The mono went way up under the tank. Rocket science for 1976. Front forks had those *weird* air chambers on top.
I remember the '76 YZ power band being very wide (good in the woods) and forgiving vs. my buddies '78, which was really sensitive to rev range/gear selection (no fun in the woods), but had waaay more suspension travel/compliance etc.

Pete



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