DT125e - what top ends/gearboxes will fit from yz/it

[metalskin]

just wondering what stuff will bolt on to my 78' DT125. looking for a 175 barrel but dont know
what is a definite fit. would a 79 it175 top end bolt straight up? does an it carb have the 2t inj
inlet on the carby? is the dt gearbox ratio the same as the it? could i run a it/yz hybryd cdi ignition?

basically what model it/yz parts are interchangeable. any help is much appreciated. cheers, metalskin.

[Colin Jay]

I know that the DT125a/b/c/d and DT175a/b/c/d share the same base gasket (along with most of the bottom end bits) as do the early YZ125s, so the DT175 topend should bolt straight onto the 125 cases. The IT175's used a different base gasket, and I presume that they share more parts with the YZ125E/..., and very little with the earlier DT125/175 engines.

CJ

[David Lahey]

The barrell stud pattern changed with the IT175D and YZ125D from what was on DT175A/B/C/D/MX125/MX175/YZ125A/B/C/X and TY175B/C.
On the DT125/175 motor the design changed with the E model - so a D/E/F model IT175 top end is what you should be looking for if you want an IT175 top end for your DT125E. Don't know if DT125 crank case mouth needs machining to bigger diameter or not.
No idea about the gearbox ratios or the mix n match ignitions.
The 34mm IT175 carby does not have an oil injection nipple

[metalskin]

I know that the DT125a/b/c/d and DT175a/b/c/d share the same base gasket (along with most of the bottom end bits) as do the early YZ125s, so the DT175 topend should bolt straight onto the 125 cases. The IT175's used a different base gasket, and I presume that they share more parts with the YZ125E/..., and very little with the earlier DT125/175 engines.

CJ

yeh i've done a bit of research and figured that much out myself, but i cant find any modded DT125E's so thats why im asking.

im sure it would match up with something? just noticed a new reply as i went to post this that covers the IT changes,

what about the yz, would it be the same as the IT? d/e/f models? and what i ment about the ignition was an IT coil/flywheel with
the cdi box thing from a yz125? cheers for the replys. metalskin.

[Nathan S]

The DT125E has bascially the same motor as:
YZ125D~F.
All IT125.
IT175D~F.
All monoshock DT125.
All monoshock DT175 until the safety seat model (which arrived in 1985, IIRC).

Major differences are:
The YZ125F and IT125 have a different exhaust mounting on the barrel.
YZ125F has a smaller crankshaft taper.
The YZ125F also has different gearbox internals, but I don't know whether they fit into the case easily or not.

The later DT175 motors are also very similar overall. If you use a matching piston, barrel and conrod, then those bits can be fitted to an earlier motor.

[Freakshow]

what about the YZ125 G any 175's slot onto them ?

[vandy010]

the later model AG175 barrel also has the same stud pattern as the DT125e and all those models Nathan mentioned.
i have 2 AG175 barrels here with pistons/carbys etc should you want to give em a go.
i'd be keen to swap my 175 top end for your 125 top end. if you like and i'll cover postage.
providing of course theres still a few overbores left in that barrel of yours.
just a thought...

[Nathan S]

what about the YZ125 G any 175's slot onto them ?

IT175G/H, and possibly IT175J/K - but beware the exhaust port location on the later J/K (they might have gone to a centre port, I can't remember).

[cyclegod]

what about the YZ125 G any 175's slot onto them ?

I put my spare IT175H top end on my YZ125G back in the day, it was the best mod I ever did for that peaky P.O.S and it was so much better to ride fast trails on too.

[metalskin]

what about the YZ125 G any 175's slot onto them ?

I put my spare IT175H top end on my YZ125G back in the day, it was the best mod I ever did for that peaky P.O.S and it was so much better to ride fast trails on too.

i used to have a yz100g and it had a massive port job and ran a 2mm os wiseco piston, never seen an old bike go so hard.
was unbelievably quick. had a real soggy/heavy feel coz of the suspension, road trail on the rear.. would fishtail to 3th gear on bitumen.
could stay in band all through to 6th and it was geared for about 120k top end. because of the porting it blew the side of the barrel out,
got a 100h (i think) top end with a stock port and 0.5mm standard 1 ring piston and it felt like it lost 40% of its power. couldnt stay
in band while going through the gears, only to 3rd, then a lag to 4th, longer to 5th and couldnt hit band at all in 6th. 

[metalskin]

the later model AG175 barrel also has the same stud pattern as the DT125e and all those models Nathan mentioned.
i have 2 AG175 barrels here with pistons/carbys etc should you want to give em a go.
i'd be keen to swap my 175 top end for your 125 top end. if you like and i'll cover postage.
providing of course theres still a few overbores left in that barrel of yours.
just a thought...

not really after ag stuff but i might be interested if you want to sell some stuff
for now i want to keep my top end. i would like to get a few spares before i think of selling anything.