Greetings,
I would greatly appreciate it if one or more of you Sachs engine experts would either confirm or discredit the statement below.
I am under the impression that the later Sachs pistons that are for the alloy top end, CAN be used in the earlier cast iron cylinders. True or false.....
Thank you,
Paul
Paul I am not sure what the experts would say, but I have mixed and matched them for years. If I have a question as the spacing (top of piston to head) I just measure it (with clay). I also make sure the piston pin placement is the same as far as the old piston I am replacing. I hope this helps.
Ron Carbaugh
Do you have to set bore clearance any different for iron cyl. ? as opposed to the aluminum ?
Thrownchain,
I always set them up at .003" and I break the steel cylinders in a little easier than the Aluminums. Why I don't know except I feel the Aluminum housing expands faster and easier than steel. These are unscientific ways of doing this, but they have worked for me over the years. Hope this helps.
Ron Carbaugh
Ditto with what Ron says!
Thank you gentlemen, I appreciate the information...:)
PS, If you use an old seizeco piston, go .004
Good point Kip.
Ron Carbaugh
" Back in the day ", the local shop wouldn't use one of those "seizeco" pistons unless nothing else was on hand, and then they would use the next over sized rings filed properly to the correct end gap as to get a little more cylinder wall tension, as the originals would allow for blow-by almost right off the bat.
The shop I mention was an engine building shop that built large displacement race engines for everything from stock cars, to drag boats to dragsters, so they knew there stuff. The Penton cycle dealership was bough by them when Fran Kupec gave it up just so they could get their bikes and parts " a tad cheaper ", they didn't realize that I came with the dealership till after the sale :) I mention this to provide some background and credibility to their work. I have mentioned before how John Penton hand carried one of their dynamic balanced Sachs cranks all the way back to Europe and KTM and Sachs, that is how much he thought of their work as well.
Please correct me on my thoughts below as needed.
I think in this thread we need to differentiate between doing a restoration or putt-putt around the pits engine, verses a race engine.
I would have to think that if a person was building a race engine with an alloy top end, he would not want to use the older style piston. The newer style piston with the dykes top ring has to be the best bet for that application, in my opinion.
When I asked my original question above, it was because a restorer asked me if the newer style piston could be used in a cast iron jug on a Steel Tanker, to which I replied I felt it could, but I wanted to confirm my thoughts, which you gentlemen did and I surely appreciate.
My concern now is that someone may consider using an older style piston in his alloy top end race bike project, and I do not want to mislead anyone.
Please feel free to correct my assumptions and comments, as the goal here is to learn from others and to possibly keep someone from making a mistake with their project...:)
Paul
Personally I'd say use the newest construction piston you can find. Overall quality should be better.