'73 250 engine rebuild questions- Help?

[Big Mac]

Need a little direction from you experts, if you'd be so kind. I've lready searched past postings with little luck, so please kick me soft if these questions should have already been figured out by an old-non-running Penton owner of 3 mos.

My Harescramble 250 project came with an engine that looks good except for a broken case/motor mount at the rear left where the large insert nut was supposed to be. I'm in process of swapping cases from a junk motor to correct the problem. Got her all apart OK--now the challenges:

1) The main crank bearings look and feel ok, no up-down movement. Looks to be a job to rebuild/replace these. Should I go with it, or bad idea since it's apart? If replacement is suggested, any ideas on who-where to replace these and get it all back in good shape?
2) I got the seals out, the left case crank bearing out and reomoved the two-each side clutch shaft bearings and countershaft bearings. I suppose I'm smart to replace all these bearings too, or is that needed? The look and act fine.
3) There's a little water corrosion in the case below the crank, small about the sixe of a dime and maybe 1/16th" deep. Needs to be patched up? JB Weld, or heard mention of some mystery epoxy? Want to make sure nothing pops loose down there and ricochets around inside later.
4) Good idea to paint inside of cases for anti-corrosion? How about inside the crankcase? What kind of paint should stick and stay?
5) I stuck the two good case halves together for a look-see...the deck below the cylinder seems to be nice and flat, but looks like it's off a smidge front-to-back. If you run your finger over the vertical seam in the crankcase, it's probably 1/16" difference. Need to grind this to get it to match up a lot better? If you don't?
6) Last, any ideas on how to press the crank back into the left case bearing? Supposed to be a pressed fit, and pretty sure bangin' it from the right is not such a plan. There a special tool for this?

Sorry for the long list---hope I'll be a smart guy with all your feedback and not be back again all goofy when it comes time to reassemble. Thanks a lot! Mac

 

[rob w]

Hi Mac,

 This is what I would suggest you do. Replace all bearings in both case halves and connecting-rod bearing also. Note: You must attain a copy of the KTM "Repair Manual" and read it through before any reassembly.Recently a fellow POG member was kind enough to send me one, and ask me to pass it on if I already had it, you may be the lucky recipient if you choose to pay the 3.95 shipping.

 "JB Weld" will work fine.

 Do not paint anything inside the cases.

 The outside seams of your case halves do not need to match perfectly in the areas that don't matter. Do not grind on the outside of your cases.

 The crank should not have to press into the L.H. case half.
 
This is pretty important stuff, just want to help you get it right. I'm too chicken to do it myself, right now I'm waiting to have someone start my rebuild. Good luck and let me know on the manual, I'd be happy to send it to you. Bob w.

 

[Kip Kern]

Big Mac

The crank bearing is removed from the left side prior to splitting the cases.  If not, you can press it out once the cases are seperated and the crank removed.  Upon assembly, after installing appropriate seals etc, place the crank in the left case along with the rest of the transmission goodies, place greased gasket and shift rod alignment dowels and place case halves together.  Torque all case screws to 5ft lbs remove dowels and now check crank end play and shifting.  If all is OK, press in your left side crank bearing as it does have a press fit on the crank as well as the case!  Get a Penton shop manual as suggested earlier.  All of this info is in it and rebuilds of KTM engines are very simple.  About ten times easier than Sachs!  The only item you have to worry about shimming is the crank!

 

[[email protected]]

Rob W., I am currently rebuilding a 74 400 and I would like to have acopy of the KTM repair manual. I will gladly pay whatever cost, please e-mail me at [email protected]. for arrangements.
       Thanks!

 

[rob w]

See, there ya go, that's why I don't rebuild them myself yet. I did'nt find that about the L.H. main bearing in the manual.
 Jeff, I have only the one extra manual and since I've already offered it to Mac we'll have to wait and see if he would like it first.

 

[mosesnra]

im in the middle of a 250 harescrambler rebuild also and would like to get a copy of the repair manual too. perhaps a realy good pog member might make a few copies on the old xerox machine for a few fellow members. id even pay up for the service.....

dean    [email protected]

[Mark Annan]

You can get the manuals from Larry Perkins or Al Buehner.

Mark

 

[Big Mac]

Bob, Kip and All-- thanks a lot! I've got a Penton-KTM repair manual already (I'd be nuts to tear in this far without it) so send it on to someone in need. The advice on the LH bearing is great Kip, the manual wasn't clear. I'll have the crank bearing replacement and shimming done by the pros --got a quote of $75 labor + parts, so worth it vs. me and my Home Depot tool set. The rest I think I can do.

On the case halves matchup, it's the INSIDE of the crankcase I'm concerned about--deck top looks to match close enough but there's a noticable ridge inside where one half sits back a bit from the other side. Don't think the fuel load flows much in the front/back (vs. the sides) or piston gets close enough to worry, but?

Regarding JB Weld for case corrosion inside crank area--saw something about an old POG newsletter that talked special prep or special epoxy. Anything else to that repair to be safe, or common sense and go for it?

Kip---the shift rod alignment dowels...can I buy those from Al or Larry? Or whittle them up with a pocket knife from wood dowels--they look pretty simple, no?
Thanks a lot guys! Mac

 

[rob w]

Jeffa,
 Email me your address, I've got a repair manual for you. [email protected]

 

[Kip Kern]

Mac

The dowels can be made from an aluminum rod or steel.  They just stick into the shift rod ends to help alignment into the right case.  Things get a little busy when placing case halves together as the shift rods have to hit the three holes as well as the shift shaft alignment in the right case as well as the layshaft too! etc....

 

[Mark Annan]

You can get the manuals from Larry Perkins or Al Buehner.

Mark

 

[Big Mac]

Bob, Kip and All-- thanks a lot! I've got a Penton-KTM repair manual already (I'd be nuts to tear in this far without it) so send it on to someone in need. The advice on the LH bearing is great Kip, the manual wasn't clear. I'll have the crank bearing replacement and shimming done by the pros --got a quote of $75 labor + parts, so worth it vs. me and my Home Depot tool set. The rest I think I can do.

On the case halves matchup, it's the INSIDE of the crankcase I'm concerned about--deck top looks to match close enough but there's a noticable ridge inside where one half sits back a bit from the other side. Don't think the fuel load flows much in the front/back (vs. the sides) or piston gets close enough to worry, but?

Regarding JB Weld for case corrosion inside crank area--saw something about an old POG newsletter that talked special prep or special epoxy. Anything else to that repair to be safe, or common sense and go for it?

Kip---the shift rod alignment dowels...can I buy those from Al or Larry? Or whittle them up with a pocket knife from wood dowels--they look pretty simple, no?
Thanks a lot guys! Mac

 

[rob w]

Jeffa,
 Email me your address, I've got a repair manual for you. [email protected]

 

[Kip Kern]

Mac

The dowels can be made from an aluminum rod or steel.  They just stick into the shift rod ends to help alignment into the right case.  Things get a little busy when placing case halves together as the shift rods have to hit the three holes as well as the shift shaft alignment in the right case as well as the layshaft too! etc....