79 KTM 400 GS80

[JCHubbard]

Just got through washing this bike about an hour ago.  Bought it in April and finally got around to doing a little shakedown woods run (6 hours) yesterday.  Very impressed. Strong & quick motor (actually it's a rocket:)), ergonomically correct, agile, fantastic braking, and tracks well without front end deflection. The only problem is that it's geared just a tad too high.  Ordered a 13 tooth sprocket from Al B. today. Other than that, this bike is good to go.

Probably going to retire my big bore Maicos and Husqvarna and use this bike exclusively for AHRMA racing next year.  

Also have a very fresh 78 KTM 400 MC5/GS with the enduro set up/kit that I resurrected about 3 years ago. It only has about 45 minutes on the rebuilt motor and new suspension. It's very smooth & tractable, handles well, great braking, but I really never put it through the paces because the motor still needs to be broken in.

Nonetheless, I'm very impressed and pleasantly surprised at how much I like the 79 though.    


JC Hubbard

[JCHubbard]

Does anyone know if this will fit on a 78/79 400: http://www.ebay.com/itm/NEW-1978-Penton-KTM-GS6-GS-125-175-250-MUFFLER-END-PIECE-Silencer-Pipe-Exhaust-/271510604553?hash=item3f374b0b09:g:e5IAAOxyF0pTi0j8&vxp=mtr

If it doesn't, is there an alternative? I would like to quiet them both down a little.

[454MRW]

Definitely not.
 Those are GS-6 pipe specific. A Sparkly spark arrestor can slip over the end of the stock pipe, but won't reduce sound much
 The stock pipe isn't very loud, have you repacked the end silencer insert?

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978-1979 MX-6 175 & 250 KTM's
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[JCHubbard]

Thanks Mike. Kind of figured they didn't.  The packing is good on the 79. I know several years ago that you could buy a universal Cobra Sparky spark arrestor.  After a pretty long search today, it appears  they don't make them any. I'm sure a used one will pop on ebay at some point.

Biggest reason I'm looking for an SA is because I ride on a friend's family farm which is heavily wooded and could be a potential tenderbox on a very dry fall day (like this past weekend).  I really like this bike and plan on riding it alot there this fall, and so I just want to do everything I can to mitigate any potential fire hazards to his land and definitely not become a "noise" nuisance.

Anyway, sooner or later, I'm pretty sure I'll find one.  Thanks for your help.

[454MRW]

I'll look in my shop, I may have one if it will fit the pipe. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978-1979 MX-6 175 & 250 KTM's
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[Bill Campbell]

Good to see one of these back out there. I am just in the process of getting mine running again. On my last ride I couldn't shift out of first. Turns out the plastic spigot that the shift drum spins on broke.I'm not sure if it was the original but it sheared off right at the base. I have had trouble with engine vibration due to worn cases which I am slowly rectifying. Before it stopped I found the motor/pipe combination gave a a very controllable surge with an excellent hit higher in the rev range. I thought the gearbox was the best shifting one I had. Being a short person I found the frame great for riding through the bush. I enjoyed the handling and the conical front hub does work. Out of interest JCH could you tell me the type and length of rear shock you are using as I have never been able to get original info on the shock length.
Cheers Bill

[JCHubbard]

Good morning Bill. I agree: "the motor/pipe combination gave a a very controllable surge with an excellent hit higher in the rev range."

With regard to the shocks, my bike came equipped with a tired set of Marzocchi 13.5 inch shocks that definitely needed a rebuild.  Didn't feel like waiting for the shocks to rebuilt, so I bought a set of 13.5 inch Progressive shocks.  Based on some research that I did on here specifically about the KTM 400, I opted to go with a 140/190 spring as per Daniel McEntee and Dwight Rudder -- based on my weight (225 pounds).  You could also use the 140/200 -- the spring is one inch shorter.

Here's the thread: http://www.pentonusa.org/forum/topic.asp?TOPIC_ID=13032&whichpage=1&SearchTerms=KTM%2C400%2Cprogressive%2Cshocks

I wasn't expecting anything great with these shocks, but I was again, pleasantly surprised, at how well they worked.  Rode up and down rutted rocky inclines, creek beds, bombed runs through the fast sections, and the front and rear of the bike were stable and plush.  

My 78 KTM 400  has completely rebuilt fox shocks (13.5 inches) and they really are very good.  So yeah, some day soon, I'll get the 79's Zokes rebuilt, but for the meantime, the Progressives are working just fine.

[JCHubbard]

quote:Originally posted by 454MRW

I'll look in my shop, I may have one if it will fit the pipe. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978-1979 MX-6 175 & 250 KTM's
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

Thanks Mike!

[454MRW]

Mine measures 2.75 ID which is quite a bit bigger than that 2.375 of the pipes, sorry. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978-1979 MX-6 175 & 250 KTM's
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[JCHubbard]

quote:Originally posted by 454MRW

Mine measures 2.75 ID which is quite a bit bigger than that 2.375 of the pipes, sorry. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978-1979 MX-6 175 & 250 KTM's
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

Mike, thanks for taking the time to look and for taking the measurements of the exhaust.  I'm sure I'll find one at some point.

[JCHubbard]

Here's the 78 with a newly installed Clarke (MC5) gas tank with new tank decals.  Received it yesterday and installed it today. Fits fine -- no mods or heat guns needed.

[Bill Campbell]

Very well restored bikes you have there JCH. Thanks for the shock info. The Zokes definitely have the tendency to lose their rebound dampening which is a pain. A rebuild is what I might have to do to mine in the future.

[JCHubbard]

Prepped this bike for tomorrow's 2 hour Hangover Harescramble at the Wicomico Motosports complex in Maryland tomorrow.  Today it's supposed to rain/sleet all day and well into the night.  Not quite sure if I'm going to be up for thrashing my old bike through that muck tomorrow. We'll see.  

Anyway, I finally found an Answer spark arrestor for it and through a little DIY fabrication I was able to make it work and mount it securely.  It works well, and even moderately quieted the bike down.
 

[Larry Perkins]

The next generation of motor in the 80-81 twinshocks are even better.  A bit lighter, broader power, and better shifting. Same AHRMA class, GP.

Larry P

[JCHubbard]

quote:Originally posted by Larry Perkins

The next generation of motor in the 80-81 twinshocks are even better.  A bit lighter, broader power, and better shifting. Same AHRMA class, GP.

Larry P

Wow, that would be a nice addition Larry. Would've been the 420, right? Had an 81 KTM 250 GS, and it was a nice bike. It was little tall, and definitely didn't turn as well as my 78 & 79 400s, but it was a very nice woods bike. Of course now I'm very partial to big bores.  

Never thought I'd say this -- I actually like this bike better than my 78 & 79 Maico 400 GS's. Been an avid Maico guy since I was 13 years old. Except for the lack of primary kicking, this bike does just about everything better than my Maicos (still can't believe I'm saying this -- but it's true, at least for me anyway).

As I said in the beginning of this thread: Very impressed. Strong & quick motor (actually it's a rocket), ergonomically correct, agile, fantastic braking, and tracks well without front end deflection And the clutch action on this bike is as light as my 77 Penton 250 GS6. The same, regarding the clutch, can't be said for the 78 400...even the magazine tests that I have from back in the day complained about heaviness of the clutch. Still, there both nice bikes.