engine repair

[RIck]

I have a 75 penton 100 which ran when I parked it in the late 70's.I am starting to restore it and have questions about what I should do with the engine. At this point it was moderatley used and all original. I can turn a wrench but I've never broken down an engine. SHould I automatically take it all apart and rebuild? At first it was locked up. I took it off the bike and oiled it up, tapped the top of the piston, broke it loose and now it turns over smoothly. Should I assume that all the seals and gaskets are bad? Any advice on what and how much I should do would be greatly appreciated. Also can I buy a manual and do this myself or should I get help? I really want to try it myself as I bought the thing new when I was a 15 year old and have drug it around the country for the last 25 years.(I'm attached) And lastly if I give up and get help could most any bike shop do this on a old sachs engine or should I search for someone with specific knowledge of this engine. Thanks Rick

 

[hrbay]

I would recommend reading as much about two stroke motors as you can before tearing into a rebuild. This one may be ok if the rings and crank seals are not gone, clean up carb. etc.. But... everyone needs to start somewhere. A Penton is a little different and learning can be done on another motor first, just a junker to see whats going on, rebuilds can be straight forward if you are patient measure things and take notes, but can just as easily turn into parts for sale on ebay. Keep reading this forum, it's loaded with hints and tips on keeping these scoots purring. By the way I think you will need some special pullers for the Sachs engines. May be a good place to start. GC

GC

[Steve Minor]

Rick.....Welcome aboard...First thing you should do is get the manual(s). Go to the "Parts" section of this home page. There you'll find several sources for manuals and parts. I know for sure that Al Buehner (216) 651-6559 or Larry Perkin (417) 865-8884 has about everything you'll need. This web site is loaded with great guys that are willing to advise.

Happy Trails
Steve Minor

 

[Kip Kern]

Rick

Get a Penton shop manual from Al Buehner and a Clymer M427 Sachs manual.  Read them for a few days to become familiar with the components.  Yes, I would at least replace all seals and gaskets and ball hone the cylinder.  The engines are easy to take apart and rebuild, all you have to do is take your time and watch where all of the shims go.  First, take the head, cylinder off and set aside, now pull up on the rod to check piston end play and needle bearing slop if any.  Remove piston and pull up and push down on the rod check it.  Then take the ignition completely off, after marking the timing, and set aside.  Now take the complete clutch assembly off, and crank gear and set aside (a strap wrench and 1/2" air impact will work on the crank gear and pinion gear but holders are available from Al), the countershaft sprocket, nut, spring washer too and the gear selector boss assembly.  You now have a basic bottom end.  Here is the important part:  Do Not Loosen Any Case Screws!  With all of this stuff off, you should always check the end play on the crank shaft, main shaft, lay shaft, and starter shaft simply by pulling and pushing on them, or bumping them with a dead blow hammer to see if there is any noticable "slop"  The book gives you a .004 measurement on each but I allow .006-.010.  If the end play on each is suitable for you, Now you can loosen up the case screws and pull apart the cases.  Now is the time to slowly seperate the cases.  Note: If you noticed excessive end play on any shaft, make notations and this shaft will have to be re shimmed.  If the end play mentioned earlier was OK, simply watch and be certain where the shims are placed.  Once apart, replace all gaskets and seals and then reassemble in reverse and be sure to check end play after case assembly and tourquing the case screws to 5ft lb.  There you have it!..   Get the manuals though as they will clear up questions.  If you get stuck, write or call  765-668-8038!

 

[Randy Kirkbride]

Kip,
You make it sound so difficult.  I can do all that with one finger.   I just call Doug Wilford!!!

 

[john durrill]

Rick,
 you need a puller for the mag or motoplat flywheel and the countershaft sprocket. both the nuts on the right side of the motor are left handed threads. the one that holds the counter shaft sprocket on and the magnitio on.
 you need a protective cap on the countershaft when you use the puller on the counterchaft sprocket. its in the book but lots of folks have twisted off the crankshaft end when trying to remove the nut ( going the wrong way).
 and with out the protective cap, the end of the countershaft will be damaged or broken.
if you need help just ask the folks here on Pog. they will help.
John D.

 

[hrbay]

I would recommend reading as much about two stroke motors as you can before tearing into a rebuild. This one may be ok if the rings and crank seals are not gone, clean up carb. etc.. But... everyone needs to start somewhere. A Penton is a little different and learning can be done on another motor first, just a junker to see whats going on, rebuilds can be straight forward if you are patient measure things and take notes, but can just as easily turn into parts for sale on ebay. Keep reading this forum, it's loaded with hints and tips on keeping these scoots purring. By the way I think you will need some special pullers for the Sachs engines. May be a good place to start. GC

GC

[Steve Minor]

Rick.....Welcome aboard...First thing you should do is get the manual(s). Go to the "Parts" section of this home page. There you'll find several sources for manuals and parts. I know for sure that Al Buehner (216) 651-6559 or Larry Perkin (417) 865-8884 has about everything you'll need. This web site is loaded with great guys that are willing to advise.

Happy Trails
Steve Minor

 

[Kip Kern]

Rick

Get a Penton shop manual from Al Buehner and a Clymer M427 Sachs manual.  Read them for a few days to become familiar with the components.  Yes, I would at least replace all seals and gaskets and ball hone the cylinder.  The engines are easy to take apart and rebuild, all you have to do is take your time and watch where all of the shims go.  First, take the head, cylinder off and set aside, now pull up on the rod to check piston end play and needle bearing slop if any.  Remove piston and pull up and push down on the rod check it.  Then take the ignition completely off, after marking the timing, and set aside.  Now take the complete clutch assembly off, and crank gear and set aside (a strap wrench and 1/2" air impact will work on the crank gear and pinion gear but holders are available from Al), the countershaft sprocket, nut, spring washer too and the gear selector boss assembly.  You now have a basic bottom end.  Here is the important part:  Do Not Loosen Any Case Screws!  With all of this stuff off, you should always check the end play on the crank shaft, main shaft, lay shaft, and starter shaft simply by pulling and pushing on them, or bumping them with a dead blow hammer to see if there is any noticable "slop"  The book gives you a .004 measurement on each but I allow .006-.010.  If the end play on each is suitable for you, Now you can loosen up the case screws and pull apart the cases.  Now is the time to slowly seperate the cases.  Note: If you noticed excessive end play on any shaft, make notations and this shaft will have to be re shimmed.  If the end play mentioned earlier was OK, simply watch and be certain where the shims are placed.  Once apart, replace all gaskets and seals and then reassemble in reverse and be sure to check end play after case assembly and tourquing the case screws to 5ft lb.  There you have it!..   Get the manuals though as they will clear up questions.  If you get stuck, write or call  765-668-8038!

 

[Randy Kirkbride]

Kip,
You make it sound so difficult.  I can do all that with one finger.   I just call Doug Wilford!!!

 

[john durrill]

Rick,
 you need a puller for the mag or motoplat flywheel and the countershaft sprocket. both the nuts on the right side of the motor are left handed threads. the one that holds the counter shaft sprocket on and the magnitio on.
 you need a protective cap on the countershaft when you use the puller on the counterchaft sprocket. its in the book but lots of folks have twisted off the crankshaft end when trying to remove the nut ( going the wrong way).
 and with out the protective cap, the end of the countershaft will be damaged or broken.
if you need help just ask the folks here on Pog. they will help.
John D.

 

[deek]

Hi Rick and welcome!!!
Don't assume the the internal parts are in good condition. I just split the cases on (1251/6B) what seemed to be a new engine. Behold the crank (was stuck)was pitted with rust, along with the main bearings, not sure if useable now, and the clutch was in the same condition. I would advise to look inside. Good luck Rick!

Dale

 

[Larry Perkins]

Welcome to Pentonia.  You have, since 1975, been a Pentonite but just now have you discovered you had a home.  

I am the lazy one in the bunch and would do different.  I would get a manual, read up, and pull the topend.  If the clearances were good and the rod had no up and down play and was smooth.  I would clean the carb, replace the top gaskets, replace the needle jet, clean the air filter, clean out the tank, and put in fresh tranny oil.  I would check for spark.  If that was good I would put in a fresh plug and fresh gas.  Then I would turn on the gas, tickle the carb till it peed, and kick it till it starts which probably wouldn't be but a few kicks.  Then I would ride it and see if anything else presented itself.  If it did and it was major, like Randy I would call Doug Wilford.  He is definately the best Sachs guy.  He was Penton team manager and ISDT and enduro racer back in "The Day".  He even put in some time at the Sachs factory.  

Anyway, Welcome home brother!  Enjoy-Enjoy.