Sachs "D" porting

[bentrims]

Well this surely has been a hot topic lately but what IS the difference in the D porting? Slightly advanced intake timing making it pipey? Lower exhaust window stacking more compression? I dont know!

When I press in that new sleeve what can I expect?
Thanks for any input. GO PENTON!
TB

[john durrill]

Tom,
 If you get a chance give me a call and i will pass along the things i have on D porting,
John D.
 386-752-9290

[bentrims]

Thanks so much John!

[Larry Perkins]

D porting wasn't really much different than B.  Biggest difference was the intake manifold.  It is D GS porting that was the stink.  There is a big misconception on the D.  What was hot from several angles was the D GS and D GS Pro.  That porting can not be duplicated without welding in the transfers, reboring the liner, and changing the transfer size and shape.  The GS and GS Pro had wider but not as high a transfer port on both sides.

Larry P

[bentrims]

Thanks Larry,

That is puzzling that they would ban a motor based on porting when the first thing a racer does is see how wild he can open ports.
GS pro sounds really wild. Stuffed cases too.

[Larry Perkins]

Stuffed cases, internal rotor Motoplat, and the very last ones had feathered ear exhaust port with a bridge in the middle to help keep the rings from hanging.

Larry P

[bentrims]

Wow winged exhaust...what kind of HP did they claim compared to a B Sachs?

[Larry Perkins]

Don't know that.  But they were noticeably faster seat of the pants.  Enough faster that I believe the GS and GS Pro should not be in Classic class.  Even though Penton popular opinion might be different I am operating off of the fair and equal principle.  The regular D I have no prob with but GS and GS Pro I think are slower Sportsman bikes and should not be given Classic status.  I know Kent won't agree since their D is a GS.  Perhaps that explains to others the personal battle with what AHRMA is really debating about.  I just think AHRMA doesn't understand the difference between the D and the faster GS and GS Pro.

Larry P

[firstturn]

Very well spoken Larry.  I like the "seat of the pants" measurement.  Sure worked for me over the years.

Ron Carbaugh
Kerrville, Texas

[bentrims]

Larry,
Thanks for that input. These Sachs motors are just plain fun to work with even if I only know enough to be dangerous.
Tom B
PS..Are you going to Moberly?

[Larry Perkins]

Not going to Moberly.  Broken collarbone still healing.[B)]  Shooting for ISDTRR.  Wish I was, as it and Casey are my two favorite Vintage tracks.

Larry P

[bentrims]

Ohhhh, I remember reading that a while back. Glad to hear the track is a good one. Is it at all tight to the advantage of a 125 or is it a fast one?

Casey is really a good one. Off camber turns like back in the 70s. I dont see that on too many modern tracks.

[Larry Perkins]

It is pretty fast with a couple of good flat track sweepers.  It has a starting gate and good dirt.  The owner works it all real good too.  Have fun!

Larry P

[bentrims]

I am starting to daydream about that ISDTRR a bit. Would I need to go back to a toaster tank on my 125 or will the MX tank do fine?
Thanks Larry,
Tom B

[Larry Perkins]

ISDTRR gas stops are not far apart and an MX tank should work fine.

Larry P