Help, I think I'm a new Penton Owner

[oscar]

Hi guys, this is a great forum.  I mainly rescue and rebuild old Honda ATCs, but like all great stories start....   I found this old dirtbike in a barn.   Here's what I know about it, it has a KTM engine in it #54 30 003 010 (from the top of the left side case near the kickstarter but behind the jug i.e. under the carb) the numbers on the frame by the steering head are 855113xx there are only 8 digits on the frame.  I'm guessing the frame is a 1978 Penton 400 but from the numbers on the engine I think it's a 250.  The bike is in great condition, has a fiberglass gas tank, fiberglass seat pan, plastic front and rear fenders, I think they are marzocchi forks (it was dark last night and I didn't write down the name and can't spell) Any how from pictures of old Pentons I've seen on the web I'm pretty sure it's a 77 or 78 Penton 250/400 MC5.  This bike is complete and in great shape for it's year.  Now for the bad news, the guy I bought it from blew it up.  The piston broke,  I think this is an easy fix, crank and rod bearings feel good, and he saved all the parts/nuts bolts after he tore it down.  The cylinder doesn't appear to be hurt but it has been sitting in St Louis high humidity for a few years so it's rusty and will need a bore.  I was wondering if anyone can help me identify my bike and engine.  I meant to measure the bore last night but ran out of time.  Can you post the bore sizes of a 250 and a 400 so I can compare?  Do you know where I can order a piston kit and topend gasket kit for my Penton when I figure out what I have.  I can take some pictures tonight if that will help identify it.  Thanks for any help you can provide.  If this ends up being to expensive my wife may make me sell it, but it appears to be a simple top end rebuild depending on parts availability.  Happy Holidays.  Oscar

I like old bikes

[Steve Minor]

Hi Oscar.....Welcome aboard....You've come to the right place for help. These guys (and gals) are great and are always willing to help. First thing to do is identify your new find.....What color is the frame,tank and side panels? If it's a red/orange frame and white tank and side panels, I'm saying it's a 78....Once identified, get the proper manual from Al Buehner (info listed below). Also, see the web sites I've pasted below and go from there.

Good Luck and have fun!
Steve


http://www.pentonusa.org/prodyears/prodyears1.asp
http://web.tiscali.it/ktm70pages/


Alan Buehner
5818 Detroit Ave
Cleveland, OH 44102
Phone: 216-651-6559
Fax: 216-651-1620

[Larry Perkins]

It is a 78 KTM you have and not a Penton as Penton was made until 1977 models.  If it is it has a orange frame and a whitetank.  The 54 series number you give is not the serial number but the part number for the engine case.  The serial number for the motor will be on the raised part of the centercase half on thew ignition side just below the cylinder.  This will help confirm it is a 1978 and it's true displacement.  Hope this Techno info helps some on which it is.  If it is a 1978 then it is a good collectible bike because it is a First Year KTM as it's own label only.

Larry P

[Larry Perkins]

Also the displacement is a 71mm to 72mm bore on 250 and 80mm to 82mm bore on the 400.  These are memory but I think correct.

Larry P

[oscar]

Thanks for all the help identifying my 1978 KTM 250 MC5.  It's going to be too much of a project for me to tackle this year so I listed it on ebay.  It's going to need a sleeve or different cylinder.  Bid if your interested.  Thanks Oscar

I like old bikes