Anyone mention "D" engines?

[Bryson Williams]

Thank you Ron.  I try and learn something everyday.  In reviewng my port spec diagram, I see that the intake ports are angled and the statement is attached.  " All port width diameters are "CHARDAL"
I have no real idea what that means,I think it means tapered of some sort.  If I had a dictionary I would look the word up. I'm a Public servant not a machinist.

I also have a stock barrel and piston out it seems to measure loosley alright.  At most we are talking 2mm to 3mm in porting it dosn't appear to be a danger.  Or am I looking at it wrong.

Dirk

[firstturn]

Dirk,
  The word is probably chamfer.  It just means beveled or rounded off.  The 2 0r 3mm is fine(if you are talking looking down the barrel(or cylinder).  I hope this helps and as always I am sure some expert will correct me if I am wrong[B)].

Ron Carbaugh

[Bryson Williams]

OK definition of "Chordal" via the computer dictionary is "A musical note", "In harmony with". nothing to do with a term for measurment or a machinist application.  Next I'll be singing Combyya in harmony with my two black labs.

Cappy need your help on this one, what does Chordal mean.  Gotta be German or Swedish and your in Germany.

Dirk

[Bryson Williams]

OK,OK, per my machinist uncle I'm screwed up.  A straight line connecting to points on a curve, is the real meaning.  A math term.

 Dirk

[firstturn]

Dirk,  
  Thanks for the new word.  I will check with my Machinist Father to see if he has ever used this term.  Just never crossed my books or terminology.  Good to learn something new.  Signing off on this subject................[].

Ron Carbaugh

[Gavin Housh]

Dirk, we have a guy out here in funny California that is a machinist/engine builder and he claims that "Your engine is my spiritual journey". So you never now when your engine builder might be in "Harmony" with your porting specs. I have an uncut NOS monark six fin cylinder that is no different than the regular old seven fin, spigot mounted carb, Penton 6/B cylinder. The ports are all in the same place. The only thing that is different is the carb mount. Someone once told me that he had a GS pro sleeve that he would let me take a tracing of, but he sold his inventory and I don't know if he still has it. The fact is that if you port the cylinder to the moon only the best experts can run the machine wide open all the time. The bike becomes much harder to ride and keep on the pipe for the average rider. As to the question about relocating the ring pins. The reason to do this is if you widen the tranfer ports. The problem in doing this is that if you widen the port in the cylinder you should also widen the port in the aluminum too. The problem with that is you only have so much metal to remove before you have a hole to the outside of the barrel. Now you could cut all the fins off, add metal to the area, revmove even more metal out, and then reweld the fins back on. The whole thing is that the barrel can only get so much of a fuel charge through the small transfer ports. The best way to get more of a fuel charge is to add a bost port. There are two ways to do this. First is to remove the liner and cut the bost passage behind the outside of the liner in the aluminum that leeds up to some kind of a window in the liner. I'm not sure about how this works, as I've not seen it done. The other way I've not seen either but it's supposed to be possible to run the bost charge up the inside of the cylinder wall between the piston and the cylinder. Must be a groove running right up the inside of the cylinder. OK time for the experts to give their two cents. I'm probably going to run a stock 5/A motor this year, it gets me around the track just fine. I find that if I set the piston up with a minumun clearance .0015 and rings gaped at .003 These engines have just enough midrange power to get you out of trouble when I make a mistake, or miss a shift on the track. If you mess up on the B motor that's fully ported you better drop down two gears to get going again. Buy the time you do that you've been passed by several bikes that don't miss shifts. So the storie goes, get your shifting right, keep your top end fresh, and hope you never miss a shift.! G man.

[john durrill]

Go easy folks .
 2 or 3mm more in port height or width is a very great difference. If i figured this right , 54 mm is 180 degrees so 2 mm is a change of 6.6666 degrees in port timing. Rule of thumb back when for port width was a max of 65 % on any port width on a 54 mm bore thats 35.1 mm? so be careful folks.
 Chordal is a math term.
I picked this off a web page with math definitions
 Chord-  A line segment that connects two points on a curve.
Here is part of an article from EC Birt that will help explain it some.
http://autos.groups.yahoo.com/group/PentonRestorationandTechGroup/files/Chordal%20port%20measurement/


  It looks like it is the width of the port measured with the cylinder opened up and laid flat. I think You can use a stiff piece of paper lay it against the inside of the cylinder and do a rubbing with a soft pencil. Lay that out flat on a table and you should have your measurement in MM or Inches.
 Ron , Doug am i missing anything with this? If im wrong some one please shoot me down , chuckle chuckle. One could make some very expensive mistakes porting a cylinder with out the right base line knowledge.
John D.

[firstturn]

John,
  I don't think you are missing anything except this porting bazaar could go on forever and then we are back to what type of oil do you think is best for a 2 stroke???  Take a hint from Gavin and unless you are a expert try running stock with a great pipe(mid range) and one would be surprised how fast of lap times you can turn.  The really fast bikes can only be ridden VERY FEW people.

chardal........chordal..........chord    all we are doing are simple drawings of port layout on a flat piece of paper***simple***

I like the last thing Larry Perkins told me when I picked up his Championship 100 Penton "be careful on the first time around the track it is difficult to ride and is VERY on/off type power.  He was/is right.  But it is Fast.  Going to bed...thanks for all the fun:).

Ron Carbaugh

[Bryson Williams]

Thanks fella's, I have a clear understanding of the word, the meaning and the theory.I only know a couple of ways to learn and that is read the subject matter, and ask questions of those who are the experts.

 I was a pain in the ass in school aswell. I live in a world where we always ask. Who,what,where,when,why and how.  nuff said !

 Dirk  

[Gavin Housh]

Ron, I see your bidding on the Banke down pipe. I've often wanted to try a down pipe on my six day, but they are very rare. If you succeed in winning the bidding on the down pipe it would be cool if you could take some measurements for purpuse of comparison and post it for the pipe building gurus. Just a thought. I was going to bid on it but when I saw it was you I left it alone. Gavin.

[Dwight Rudder]

quote:Originally posted by Bryson Williams


 I'm also looking for a 175 Sachs motor for my cross-country project this winter.

 Dirk Williams

You are aware that the 6 speed 175 Sachs engine pistons are non existant.  In Germany they replace all the 175 Sachs engines with 125s.
I have 2 175 Hercules GS175/6a and one 175/6a engine and one spare piston. NO, you can't have them.  You can put a early Jackpiner topend on a 125 Sachs lower though. You have to modify the pipe to fit. John Durril did one.
Dwight

Dwight Rudder
7 time ISDT / E medalist
8 time National Enduro Class Champion.

[firstturn]

Gavin,
  Thanks for the "nice guy" note.  If I do win it I will be happy to take it over to Kevin at Circle F pipes and let him copy it for you.  He does nice work and is reasonable.  He has been at pipe building for many many years.  You can email me directly.  I will probably take a bike over there so the fit is right on.  What year Penton are you looking at putting it on?

Ron Carbaugh

[Paul Danik]

Donny,
   Did the stock Monark pistons have a hole above the wristpin hole that was larger than the wristpin hole and went all the way through the piston? Included with some Tyran items are pistons with "superlite" written on the box with part number 0686 207 025, the 54.0mm size is crossed off and written in is the correct piston size, 54.93.  I haven't run into anyone yet who knew of the "superlite" Sachs pistons, maybe they were stock on the Monarks.
Thanks
Paul

[OUCWBOY]

Paul,
None of the Monark Piston I ever saw had a hole like you talked about. I did have a Jackpiner Piston with a longated hole above the wrist pin, but it didn't go all the way through.

Donny Smith

[john durrill]

Dwights answer is the reason we did the KTM top end swap instead of a 175/6 Sachs top end on my 175.
The 175/6 Sachs use a 60 mm piston and a 61 mm stroke. The 60 mm size was the problem. we were unable to find any pistons that would work as a replacement. At one time Yamaha made a bike ( twin) that had a piston that would work with some changes for making an alloy cylinder 125 a 152cc engine ( it had a 14 mm wristpin)
Those pistons are very hard to find.Thats what the 152 kit piston from Wiesco was based on. None of those pistons would work on a 175/6 Sachs. The wristpin size is way too small and the piston crown to top of piston measurement is way off.
     If someone has a new run of 175/6 pistons made up then with a lot of money you could make 175/6 from a 125 A engine.
hope this was some help
John D.