Helpful Hints Building A Vintage 250 MX

[Tahitian_Red]

I'm starting to put together a 1975 KTM 250 MX for AHRMA Vintage MX in 2009.  I've already gotten some good advice about pipes, but was wondering if anyone who has raced a 1974-75 Penton/KTM 250 in Vintage MX had some good tips for me.  I was only planning to do some pipe changes, add some nice shocks and find an MX tank.  After those mods I was gonna run the heck out of it before making major changes for 2010.

Besides improving my own skills, how do I put this "Falta-Nator" out front?  Thanks in advance!



The Factory Novice

[brian kirby]

quote:Originally posted by Tahitian_Red

how do I put this "Falta-Nator" out front?  Thanks in advance!

HANG ON!

Brian

'73 Berkshire

[Tahitian_Red]

quote:

HANG ON!

Brian

'73 Berkshire

Brian,

I was already planning to do that.

The "Factory Novice"

[Larry Perkins]

If you are going to MX it get the stiffer 35mm MX springs from someone like David Boydston at AMS, put in new seals, wipers, and I put some Sealsavers on to help keep things clean.  Then take a toothpick and plug the breather holes on the Ceriani fork caps.  This is an old Barry Higgins trick.  You will have to loosen the screws from time to time to let a little air out but the damping improves greatly.

On the rear shocks get ones that are a half an inch longer than stock and it will turn with the best of the Japanese mounts.  Even today KTM bikes need help in steering.  If you are setting up for Vintage in the regular shock position the Progressive shocks are plenty of shock and less money than Works.  If it is laydown or forward mount go with Works or Ohlins depending on your budget.  The gas is necessary for the extra stress.

Go with good modern tires.  Don't put Cheng Shins on because they look like old Metzlers.  They are NOT!  I prefer the 756 Dunlop for MX and the 952 Dunlop for Cross Country.  Tire is somewhat preference but those two will bite in a wide variety of terrain and last decently.  Make sure you have good fresh cables and brakes.  Check to see that you have even clutch pull at the basket also and that the throw of your actuator is in spec.

The stock MX pipe if you can find it is great and the Jemco pipe is great for MX also.  It is much like the pipe that Moiseev used on the factory bike.  You lose a bit of bottom but gain scream.  Another good MX pipe is a Cranke pipe if you can find one and they are pricey when you do because they are apparently made of UNOBTANIUM.  I don't know much about the Circle F pipe.  If it is for Cross Country the chrome tip enduro pipe is hard to beat.

If later you want to dial the motor in better I can give you some more hints but it is plenty potent like it is.  Point her straight and hang on as Brian advised.

Best of luck and I hope to see you out there this season Pentonating.

Larry P

[DKWRACER]

Larry has some good advice...if you can find a 5R cylinder, it does have some exotic porting. my 75 has a 2R cylinder which I think is a bit milder, but plenty fast for me!

Tom Brosius

[rob w]

1975 200mm (ribbed front) Ceriani forks must be altered to meet 7" rule. SEARCH POG forum, and read post "Vintage Views"

[Lew Mayer]

Easily done by changing the damper rods.

Lew Mayer

[Dennis Jones]

Get hold of a copy of Still Keeping Track issues 15 and 16. Kent Knudson has built many AHRMA championship winning Pentons and goes into great detail with lots of pictures on how to set up a bike for performance and reliability.

Dennis Jones

[Tahitian_Red]

I have an MX pipe that is in nice shape, but someone put a Super-Trapp on it.  I will be getting a 78 pipe to possibly adapt(?) and also try to trackdown a Jemco.  I always put 756 Dunlops on my Vintage/Post-Vintage bikes, so no problem there.  I have new fork springs and Ohlins shocks ready to install (13.5 or 14.25).

Rob,

For some reason my 75 has the non-ribbed Cerianis.  So, I guess that works out OK.


The "Factory Novice"

[brian kirby]

Jay,

Some of the non-ribbed forks are the long ones too, look for a "200" stamped in the slider down by the axle.

Brian

'73 Berkshire

[Larry Perkins]

I have never had them question either fork in Tech.  There are many rules that just are not adhered to.  Things like later model motors and swingarms on earlier bikes.  In Cross Country if they did check close a very prominent rider would get busted. You can make a spacer to limit travel also and leave the damper rods intact if it is a problem.

Larry P

[rob w]

Red, I believe you can purchased some past issues of SKT by contacting Doug Wilford.












Bob

[Larry Perkins]

Bob,

Among many other great things that you are is the keeper of the POG Library.  You are a great resource in paper and in person.

Larry P

[Tahitian_Red]

Thanks Bob!

The articles refer to using the enduro pipe.  I still have the enduro pipe installed on the bike for now.  I can't tell from the photo of the bike, but did they install a smaller silencer?

Two of the main issues I wanted to resovle before racing the bike were switching to the narrower MX tank and mounting an exhaust that would not be as wide at the side panel.  I know the bike will handle well, be dependable and have way more power than a Novice like can handle for awhile.  I am looking to improve cosmetics and ergos for 2009, then do the big stuff before the 2010 season.  That will also give me time to acquire the hard to find pieces. Thanks again!




The "Factory Novice"

[brian kirby]

Jay, my only real gripe with Pentons is the way the pipe pushes your right leg off the peg because it sticks out so far. On my 100 the rear section of the pipe was cut off and they put on a shorter rear cone with a stinger. I also cut down the right side cover and re-glassed it to tuck in tight to the pipe, this made the bike as narrow as possible.





This made the pipe not stick out and I never touch the pipe with my leg now. I have also seen the big bikes with the rear enduro "shroud" cut off to expose the expansion chamber giving a similar reduction in width. Someone here may have some pictures of that mod, but I think you understand what I am saying.

Brian

'73 Berkshire