125 MC5 How many are left?

[Britt Boyette]

Maybe the MC5 will have to sit for a bit longer Thom as it looks like I will have to miss the Nov. Woodland race. Sorry, maybe a rain check for another time?

Have you considered doing the Salem indoor vintage races?

Britt Boyette
1976 125 MC5

[Dwight Rudder]

The 1976 125 Penton / KTM engined bike had major issues. I never knew one to run more than 30 miles. My boss had one that he finally parked. It broke engine cases and couldn't stop it from seizing.  When he closed the shop in 1982 he sent it to the dump (very sad). It looked show room new.  It had less than 60 miles on it. I think I remember Dane putting a 1976 top end on a Sachs bottom end and it worked.  I think most must have had problems as you find most are almost like new when they are found. Someone told me that they had one that ran fine but I never saw it.
The 1977-78 models worked well I think.

[Britt Boyette]

Any guesstimates how many of these bikes are still out there?

 What I noticed about mine when I put the fresh top end on it was that I had to stack two base gaskets to get the proper X demension on the piston. It looked like it could leak between the gaskets and I'm sure the last set had done just that. I had to pull the topend after I discovered a leaking base gasket and you could see the wet area between the gaskets. This new set has Honda Bond between the two gaskets so hopefully that will work. I 'm on the 3rd over on the piston now so lets hope it the last.

Britt Boyette
1976 125 MC5

[tomale]

Britt, it is not unusual to need to use more than one base gasket. they are built to work that way. I sort of allows you to fine tune your motor to fit your situation...
As for riding my MC 5 no worries, I discovered a couple of days ago that the supplier did not send all the parts I needed to fix my shocks... my fault not his... So the parts are on their way and hopefully the shocks will be ready soon. So the bike will not be ready for the nov. race. but anytime you are ready to ride the bike and if I can get the bike to you... or if I am going.. Salem is too far... I am almost 4 hours north of Portland so that puts Salem nearly 6 hours... Each way....

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)

[Britt Boyette]

Thanks Thom! It may be the Feb H&T race but any race would be fine. I want to ride it when it's good for you.

Britt Boyette
1976 125 MC5

[Mike Lenz]

THOM
Get that MC-5 out racing. Heres what you can do to help out if running against late 70's bikes. Go to the 38mm forks with the "fluted" 80/81 damp rods and spacer them down for desired travel.  I stick with 9.5-10 inches travel to keep the bike sitting right, and slide the tubes up as far as possible.  Put some Works shocks on the back with 4 inches of shaft travel, 13.75 or 14 inch. This will give you about 10 inches travel front and back. 9 or 10 inches of travel can actually be an asset on most PV tracks as the bike still keeps the vintage feel to it concerning cornering, which the 12 inch travel bikes had lost. Are you mainly passing over jumps or in/out the corners? I'd bet corners. And of course you can make this engine go as fast as you want. Some porting, internal rotor ign and the 78/79 style pipe will make it fly, with plenty of low end. I made my kid a bike like this and I swear everytime I ride it I cant get over how the power feels like my 400 MC-5. And your starting out with much better handling than a 79 Honda. Have you ever ridden a 79 Honda. I have and believe me I would rather race a stock 76/77 mc-5 than a stock 79 Honda. In fact back in 78 my buddy got one of those and after riding my 78 KTM he sold it and bought A KTM! Be happy to help if you decide to dust it off for some Honda beating!

[tomale]

Thanks Mike, I will give it some thought...I already have a really nice pipe (the orginal Protopipe)and a Mikuni on that bike, it really helps it pull off the bottom end. a bit of porting and a little work to the carb to make it breath a bit better and the motor should really fly.. As for the those stock forks, they sure can use some help...they are too whimpy. A set of 38's would really make a difference....a set of 42's would be even better.....need to keep my eyes open for a set of those. I have a set of freshly rebuilt Fox gas shocks that I really love but they are only 13.25 in length a set of 14's would be better. I quess my only hesitation is the fact that I bought this bike new the only modifications I have done to it are the ones I did back in spring of 77. Not sure I want to mess with a historically correct Machine. It would be fun to see what I could do wiht this bike though...

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)

[Tflores]

Here is my 78 MC5 125.  Appeared to have very low hours but was in rough shape.  I completed rebuilt and restored it.  Original 36mm bing has proven to be a bit challenging to dial in but I have it real close now.  Thinking of trialing a 34mm Lectron on it.

Tom

[Britt Boyette]

78 must have had an all new engine. My 76 looks much different.



I now have a 75 250 HS coming my way that's going to give up it's engine for the MC5 cause. As usual, the engine condition is unknown.

Britt Boyette
1976 125 MC5

[454MRW]

The ignition cover is what makes it look so different. The plastic round cover gives better clearance for the rear brake lever and was used on 79-80 KTM engines and then revised again in late 1980. Also the torque pipe was introduced into production in 1978. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S

[Tflores]

Yep.  I have the original magnesium cover that came with it along with the original side panels, fenders and shocks that are in very good condition, I wanted to preserve them so I replaced them with DC plastics for racing.  The plasic mag cover is an original HiPoint aftermarket cover I had collected.  

I also have a 77/78 250 MC5 motor I rebuilt and was contemplating putting in it to compete in a local Texas Vintage Racing class that has some really great competitors in.

[Britt Boyette]

Did they revise the cylinder too? I wonder if it would work on the older 125?

Britt Boyette
1976 125 MC5

[[email protected]]

I have a 1976 125 MC5 and a 77 125 MC6. Anyone else ever hear of the MC engine having 6 gears? I've got a 34mm Lectron on my 77 and a bing on my 76. I belive that Penton ported the 77 cylinder to mild out the hit. Bothe bikes are much more enjoyable to ride with the 34mm lectron as compared to the bing.
I think w/the bing you need to make sure that you replace the slide, needle and brass needle jet barrel that holds the main jet on a regular basis or you will get surging which will be a falese indication and make you start looking for an intake or base gasket leak.
My 76 has about 60 hours on it since new. (guess b/c the original rear tire is 1/2 worn) and I've never had a problem with it. I'm surprised to hear about the problems with the 1976 125 engine. Growing up my freind Barry Avery had a 1976 125GS. He and his brothers rode NETRA Jr enduros and trail rode it for 3 seasons before ever replacing the rings.

72 Penton 6 day 125
72 Penton 175 Jackpiner
75 Penton GS6 400
76 Penton 125GS
76 Penton 250GS
77 Penton GS6 400
77 KTM 250GS
77 Penton 125 MC6
78 KTM 175GS6
78 KTM GS6
78 1/2 KTM 175GS6
76 Hercules GS175
1978 GS125 Hercules w/coffin tank
76 GS250 Herc

[ALB]

All the 125/ 175/ 250/ and 400 engines have 6 gears in them.
On the MC-5s - access to 1st gear was disabled on the shifting drum.
It's like the ads for Prego spaghetti sauce - "it's in there". You just can't access it.

The KTM 125s were good dependable engines - perfect for enduro riding but underpowered for MX competition.

Alan Buehner

[sixdazed]

Nice looking 125 Tom.I've been meaning to call you (no particular reason,just to catch up),but been busy with life in general.Hope all is well and i'll call you soon.Later,Ric