I would like to some day try and make my 125 Jackpiner competive for sportsman 125 class. If you dont know I put a Sachs cylinder on a 73 Jackpiner to try and make a good shifting reliable vintaqe Penton 100 for the 100cc Nationals they used to have in MO. Well it worked great and we won that race three years in a row...and then everybody quit comming and the 100cc national was no more. So the bike just sits there, not legal for AHRMA 100 class. I know I couldnt run it in 125 classic so Im left with sportsman. There are some fast motor scooters in that class!
I have been looking in this site and others for porting ideas. If I want to go all the way it sounds like the S or worm boost type port would help if I really opened up the intake and ran lets say a 32 Bing. I understand about how and where this port went but I cant see how it could be done without the ring ends getting into it. Were they putting the ring ends on the exhaust side? Has anybody seen this done and want to share...or am I getting into much to top secret stuff here? Also what about extra exhaust holes drilled along side the top edges of the exhaust. I've seen that before. Anyone ever tried it with a Sachs?
Mike,
I always give up too many secrets but if you do it then do it like the KTM 125 V port and run the 125 KTM piston with the window. Vroom Vroom[8D]!
Larry P
Reed valve is really the only way to make some serious horsepower. Also frees you up to use all sorts of pistons, and have more effective boost ports. By chance, I have figured out how to add two boost exhaust ports, haven't actually done it yet, but I have some dead cylinders to practise on! Might be a little different with a 100cc bore though? believe it or not the actual exhaust and transfer port timing on a Sachs cylinder is the same as a modern KTM SX 125!
Bought this complete 125 6B engine in 2004 at Mid-Ohio for $75.
DH reed valve with booster ports.
(http://i52.photobucket.com/albums/g8/BobWardlow/sachs%20engine%20stuff/cyl002.jpg)
(http://i52.photobucket.com/albums/g8/BobWardlow/sachs%20engine%20stuff/eb1018.jpg)
(http://i52.photobucket.com/albums/g8/BobWardlow/sachs%20engine%20stuff/eb1020.jpg)
(http://i52.photobucket.com/albums/g8/BobWardlow/sachs%20engine%20stuff/eb1019.jpg)
(http://i52.photobucket.com/albums/g8/BobWardlow/sachs%20engine%20stuff/eb1021.jpg)
Bob
Rob, Nice modification job. How about a photo of the exhaust port? What goes in must go out.... joe
Mike,
A friend in the Netherlands built this one up several years ago and had good results with it. You wouldn't need the water pump and drive
with an air cooled cylinder but the intake did work and did very well at the races. Down side was he would get one race to a set of clutch plates. I think their are still the parts to do this in kit form available.
(http://i439.photobucket.com/albums/qq113/sachs175/Penton%20stuff/Sachsrot1.jpg)
(http://i439.photobucket.com/albums/qq113/sachs175/Penton%20stuff/sachsrot6.jpg)
(http://i439.photobucket.com/albums/qq113/sachs175/Penton%20stuff/sachsrot5.jpg)
It made right at 31 hp.
For dirt you could build up a Can Am type intake tract . You could use the TNT rotary cover as a tested model to build from.
JP ,
What reed cage would you use ? The DH and Gems that were made for the Sachs 125's are a little small.
Get a dead CT2 cylinder and weld that reed housing on the Sachs cylinder?
Or does someone make up a kit that would work now for a 32 or so mm carb ?
john d.
Quotequote:Originally posted by joe novak
Rob, Nice modification job. How about a photo of the exhaust port? What goes in must go out.... joe
Hey Joe, How's it goin.
(http://i52.photobucket.com/albums/g8/BobWardlow/sachs%20engine%20stuff/eb1015-1.jpg)
Bob
Will a 100 liner press in a 125 barrel ? Any mods needed?
Larry,
It will work with some modifications, as the sleeve ports on the 100 vs the 125 will have a slight bit of difference in angle and position.
Donny Smith
Paragould, AR
To be technically legal, I usually use vintage period Yamaha reed cages, sometimes updating with carbon reed petals, although a modern 80/85cc block would also work good. I never use the Yamaha rubber carb manifold because they all have a tight kink in them, poor flow. The problem with good horsepower on the Sachs motor is the clutch will slip, then I have squeezed in another plate, or added three more springs, of course then hard to pull and sometimes drags. JP
Thank you, Rob. Beautiful exhaust area! It is hard to remember how "rectangular" the opening once was.... Joe p.s. We just received 3-4" of beautiful snowfall. Really! Soccer practice was cancelled last evening for our daughter, and I will cancel practice for our son this evening. Balls don't roll well in the thick snow.
What is this "snow" you are referring to?
It will hit 80 here tomorrow..... and spring is almost over....
Suppose to hit 97 here tomorrow!! Boy, I wish I had some of this sweet porting back in the day. If memory serves, I think all I had on my GS, 125 was a milled head, a little port work by my pal Jeff Piasecki. May have taken a little bit off of one on the expansion chamber cones. thats it.
JG
Scottsdale,AZ
Wow, thanks for all the ideas. John, very cool but way over my head. I know JP builds some FAST motors, maybe I will go that route. Larry, that was my first thought also. But after looking I dont see how you could use a KTM style boost port because the piston window will be open in the intake tract, with the Sachs oval intake port, when the transfers are open. The worm boost port I mentioned was the same concept except it was two channels that ran up each side of the cylinder from the bottom side edge of the liner, and opened when or just before the transfers opened on the rear side of the piston. This acted just the same as the KTM set up. But how to squeeze a quarter inch channel into the side of the cylinder and up behind the piston without getting into the ring end gaps, as they are stock anyway, is my dilemma. This would be the easiest route on my already ported cylinder I have to try and gain some extra air flow.
Again thanks for your input.
Ok Big Mike...how did the 100 cylinder I sent you work? Let me know. I will look around and see what I have as far as a 125 Trick cylinder.
Ron Carbaugh
Quotequote:Originally posted by Mike Lenz
If you dont know I put a Sachs cylinder on a 73 Jackpiner to try and make a good shifting reliable vintaqe Penton 100
I am familiar with what John D had to do to put the 175 top end on the Sachs bottom end, but how much was involved in putting the Sachs top end on the KTM bottom end? Is it as simple as bolting it up? This might be a good setup for the MT 100cc Works Revenge races, especially since they allow 7" of rear travel, put it in a 74.5 frame and lay down the shocks.
Brian
Quotequote:This might be a good setup for the MT 100cc Works Revenge races
Too heavy.
Stick with the SoCal berkie. You'll race 4 laps on a smooth vintage track. Who needs 7" rear travel. And, loose 10 pounds yourself[8D]
Ernie P.
Chattanooga, TN
You are right it would be heavy. I do have that other '72 Berkie parts bike/project frame that I could pretty easily set up a laydown rear shock setup using those max travel shocks Works Performance built for the XL250.
Brian
Brian,
I do have a 1974/5 laydown shock frame that needs work that I am not going to use. Let me know if you are interested.
Ron Carbaugh
Ron,
I might be interested, does it use a special airbox?
Brian
Brian, You have to weld/machine some more metal onto the rear of the cylinder for a base gasket match, make an exhaust manifold spacer and re angle the header pipe end of the pipe if using a Sachs pipe, not required for a KTM 125 pipe. I also reworked the intake setup to not only open up the intake for a 32mm Bing, but to also clear the cases. This is required even with the 28mm bing I used on the 100. I also used the clutch/primary gear from a KTM 125 which is geared lower and lightened, along with the all alum clutch plates and disks. That removes ALOT of engine weight and spinning mass weight. Other than the tranny being a little heavier you wind up with an engine that is similer in weight to the Sachs I would think. you also want to gear it way down or better yet make it a five speed to miss the huge gap from first to second and the neutral between second and third. Did some other things like milling the head, stuffing the crank and porting (well Ron C did that). You wind up with a good shifting reliable engine with a clutch you can abuse without it going away.
Ron, Well as I stated we won it three years in a row and apperiantly scared the others away with your cylinder, even with my petite frame gracing its chassis! Actually, I let one of my boys run the first motos and I ran the second. Since I am not going to use it in the forseeable future you can have it back if you want it. I did make the base gasket and intake changes needed for the KTM engine, but I think it would still fit on a Sachs lower end also. Maybe a swap for the 125 cylinder if you find a spare???
Mike,
I do not need the 100 cylinder, but if I find an extra Pro 125 Cylinder I will shoot you an email
Brian,
This is a bike I bought years back and it needs some frame work (from rust), but is basically compete with a stuck Sachs 125D engine. I will send you a email with more details. It would make a good project as it has the correct swingarm etc.
Ron Carbaugh
OK Ron, if you dont already have it my email is bkirby84c at yahoo.com
Brian
[8D]