Hi Friends,

I show different part numbers for these stock exhaust pipes.

DT 250 D/E - 1N6-14610-00-00

DT 400 D/E - 1M2-14610-03-00

Yet, at Boats.Net I see this notation...

"EXHAUST PIPE ASSEMBLY L
This Yamaha 1N6-14610-00-00 EXHAUST PIPE ASYL part is also used on these models and components:

1977 DT250D EXHAUST
1977 DT400D EXHAUST
1978 DT250E EXHAUST
1978 DT400E EXHAUST"

Same thing at Partzilla.

Now, outwardly the engine/frames are identical.

BUT, internally, the motors are different.

Are these pipes interchangeable, 250 D/E and 400 D/E ???

I"v just fitted the dt400 engine in my 77 DT250 [ 1M1 ] and exhaust fits , and if you buy a gasket for the 400 ,its the same size as 250.

Thanks 'Hat,

I'm not surprised that they fit, one to the other.

But I've been reading lately about 2-stroke expansion chambers and how they're designed to perform with specific piston/cylinder/porting arrangements and that the pipes are designed with complex mathematical formulas to optimize each pipe to each motor.

Since the piston/cylinder/porting arrangements are different I wondered if the pipes would HAVE to be different.

Here's a video that kind of explains why there MIGHT be a difference.

The partzilla and boats "this part is also used on these models" simply shows you the other bike parts lists the part shows up on... it does not mean the part is the same since Yamaha shared parts lists among similar models.

You have to be careful with parts like pistons/rings/gaskets on similar models as the "crossover" would lead you to believe the 125/175 or 250/400 parts are the same when they definitely are not. The best indicator is the first three digits of the part number which indicates the model code of the bike... those digits should correspond to the size of bike you are working on *if* the part is different like a piston for a 250. It can be tricky and confusing.

Roger that,

caveat emptor

Forgive me for replying to my own response but I still need some guidance on this issue.

Specifically, I have a line on a 77 DT 250D exhaust pipe in fair shape but I want to be sure that it will not only bolt up to my motor, but, that it will perform correctly as well.

I'm hoping someone might chime in who has actually ran this pipe on a 77 or 78 DT 400.

I posted a little info here. starting at post # 192

www.yamaha-enduros.com/index.php/kunena-...-400?start=190#13363

Thanks for that helpful link Devin.

I'll be watching it with interest.

I went ahead and purchased the pipe from a DT250. and can only hope that it will work properly.

I'm told it was made by an Italian company called Fresco.

It's a Fresco Pipe.

Fresco was bought out by "Big Boy" Exhaust. Also Italian.

"Big Boy" MAY have been acquired by Giannelli.

Not sure Though.

I hope this thing performs well on the 400E.

Here are some images.









Please share your thoughts...

Will it work ?

OR, waste of money ?

Be honest, I can take it !

Looks the biz " , wheres the muffler ? Fresco are desirable pipes,

Didn't come with a muffler so i guess I'll use my Turbincore 2.

I also picked up a DEP Silencer just for fun...