Penton MC-5's in post vintage classes

[Mike Lenz]

I was talking with a few of you about the subject of Penton MC-5's being competive in non AHRMA post vintage classes where all long travel twin shock bikes are run in one class 75-81.  I want to incourage you MC-5 owners that you can be competive on these bikes against the 12 inch travel bikes. For one you can easily increase the travel to 10 inches by using 14 inch shocks and 78 38mm forks. However, even though I went to 38 mm forks I have opted to leave mine at 9 inches travel due to my vertically challenged statis. Im just too far off the ground on a 12 inch bike when sitting on the seat, plus the lower the bike is the better it turns. MC-5's have the "vintage", shorter wheelbase and still turn very well...Long 12 inch bikes dont turn as well. Are you making most of your passes in the air, or in and out of the turns? The 250 is easily tuned to be as fast as you want it to be against ANY post vintage class bike. With the 400 you do have to lean on it pretty hard do to the fact you are running against 420-500cc bikes. However, on my (leaned on hard)400 I still feel I have an atvantage on a moderate, tighter post vintage track do the shorter wheelbase and superb handling. If you want to talk more about this feel free to do it here or email me at [email protected]. Lets help Penton MC-5's to live on and keep the Penton name out there in post vintage racing! You wont regret it, I promise!

[brian kirby]

I have to respectfully disagree with you Mike. The MC5s are great bikes, and as Larry Perkins says they might be nearly a cheater bike in Historic ('75-'77) class, but they are no match for an equal rider on a '78-'81 bike. I've not ridden a later '78-81 KTM but I know comparing the '77 MC5 400 to the '79 Maico 440 its not even close. Not only will the Maico leave it in a drag race, but it will easily turn inside the MC5 too, even with 2+ more inches of travel.

I do have some setup advice to ask of you though. The one thing about the MC5 that I just can not come to grips with is the turning. Its fantastically stable, turns great at high speed and in general at high speed is very confidence inspiring. It pushes in slower turns though, especially if its muddy or slick, enough that even my Mom commented that I didnt look comfortable on the bike. I've got 35mm forks, but the later rear set triple clamp that allows the forks to be dropped as low as possible. I took the springs out and collapsed the fork, then slid them as far up as they would go and not hit the fender where its bolts to the bottom clamp. It has that "stink bug" look too it but I just never can get the front wheel to feel planted. It always feels like its trying to wash out so I cant be as aggressive as I can on other bikes, even my Can-Ams which turn like a refrigerator full of bowling balls.

I'm at the point where I'm about to give up and chalk it up to me just not being able to adapt to the bike and not a problem with the bike itself.

Brian

'72 Berkshire

[Mike Lenz]

I am basing my comparison between my 1980 KTM420(which we used to call a cheater bike back when it came out) and my 77 400 mainly, and I have leaned on my 400 pretty hard to get it to run as well as it does. It has alot of porting work done to it, 40mm Bing and internal roter ign. To give you an idea a stock 400 runs a 185 main jet. My bike requires a 200. It will run with the big boys, but it does not have the torque they do. You have to ride it more like a 250, which I enjoy.

As far as the turning goes you have me somewhat stumped. I have no turning issues with that bike and honestly cant remember the front end EVER giving away on me. That being said I was also a Maico dealer in the late seventies and nothing turnes like a Maico. Maico's were a very front end handling bike, too much so for my liking. I would classify the MC-5's as a somewhat rear end handling bike, but wll short of a Husky. I feel they still turn well when set up right. Obviously, Im sure you have looked at the tire.  Some Dunlop's Ive tried lost all traction as they got just a little wear on them, espically in the mud. This happened on my 74 Penton 400.  I acually thought something was wrong with the bike.  People are flying by me and I felt as if I was on ice and they were on dry dirt. Later I even fell on a dry track from losing the front end. I thought I was forgetting how to ride!  I mentioned it to my dealer and he said the same thing happened to him with that tire. New Michilin, problem solved. It also could be a number of things all adding up. On MC-5's you need a pretty stiff seat to get up on that long tank far enough. I got some foam so hard from Al Buehner a while back I have to first drill a million holes in it! You also need pretty straight bars with those swept back mounts or you will not be getting up on the tank enough. I use Renthal Mini High bars with that mount, yea mini bike bars, they are very straight and a nice bend.  A little narrow, but no more narrow than modern MX bars. I can get you the number if you wish. Once you get the bike set up as I mentioned you will be getting up on the tank to the point that the pegs will feel too far back, at least thats what happened to me with a stiff seat and the Mini high bars. I welded peg wideners on the pegs that were 1/4 inch to 1/2 inch wider using a spacer in front of the peg, efectivily moving the pegs forward. Helped alot.  Or you can get a 77 frame with the duel peg mounts and run them in the forward/down position.  Thats even better. I know of one of those frames for sale.

Dont give up until you have tried these things. I have the option of racing my 77 400 or my 80 420(or 495 for that matter as I have a 495 cylinder that bolts right on but I like the 420 better)but I would say on about 50% of the tracks I have an equal atvantage on my 400 due to it being so short, low and flickable compared to the 420 or even a 490 Maico. That being said if your talking about riding a full on modern track you would have to go with a bike like a 490 Maico or 420/495 KTM. Most of the post vintage tracks we race on are no so. If its a modern track we are routed around the hairy jumps(= more turns)...and I dont care to do the modern high flying act anymore anyway. Its still fun...as long as you dont screw up! Im too old to hit the ground that hard anymore!!

[brian kirby]

quote:Originally posted by Mike Lenz

Some Dunlop's Ive tried lost all traction as they got just a little wear on them, espically in the mud. This happened on my 74 Penton 400.  I acually thought something was wrong with the bike.  People are flying by me and I felt as if I was on ice and they were on dry dirt. Later I even fell on a dry track from losing the front end. I thought I was forgetting how to ride!

Mike, this EXACTLY describes the feeling I get riding the bike. I raced it in a vintage CC race two weekends ago and as I said my Mom, who is an ex-enduro racer and goes to almost all of my races, pointed out that she could see in my riding that I was not comfortable on the bike.

I dont think it is the front tire, but you did highlight a few things I had not thought of, like my seat foam is VERY soft and I think I could definitely use a more straight bend of handlebar than what is on there now. I also cant find a suitable set of springs for the 35mm forks so I want to get 38s just to get stiffer springs, then balance the rear. As it is now it is balanced but both ends are too soft for me even in CC and way too soft for MX. The power is awesome, the only thing I would change with the engine is more flywheel weight, and I am going to make a brass ring to press on the Motoplat.

I'm going to try some of your ideas, like the straight bars and put a fresh front tire on, those are quick and easy and I will know right away if I am making headway. Thanks again.

Brian

'72 Berkshire

[pketchum]

Brian/Mike,

The Renthal Mini-High bars are model 757-02 if I recall correctly.  I am sure of the 757 number since I remember it as a plane.

Also, if interested I have a couple of spare sets of 38mm Marzocchi's that have been rebuilt with new seals/paint.


Phil

[rob w]

Brian,
Sounds like you need more weight on the front end.
I suggest peanut butter & hot fudge sundaes.
[B)]
Bob

[brian kirby]

Bob,

Funny you mention that, Ernie tells me the same thing.

Brian

'72 Berkshire

[rob w]

Seriously, when I switched over to a Hi-Point aluminum enduro tank, which is wide and flat on top. I can now almost sit on the gas cap - and man, does that ever make a difference in how well it turns.

[brian kirby]

I think you and Mike are on to something. With my soft seat and with the bars kinda far back I'm not getting what weight I have far enough forward.

Brian

'72 Berkshire

[skiracer]

Hey Phil, do you have a set of triple clamps to sell for those 38mm forks?  I have a set of forks with no clamps.  James

quote:Originally posted by pketchum

Brian/Mike,

The Renthal Mini-High bars are model 757-02 if I recall correctly.  I am sure of the 757 number since I remember it as a plane.

Also, if interested I have a couple of spare sets of 38mm Marzocchi's that have been rebuilt with new seals/paint.


Phil

[skiracer]

Hi Mike,  I have an interest in the frame you talked about here.  Thanks, James

quote:Originally posted by Mike Lenz

I am basing my comparison between my 1980 KTM420(which we used to call a cheater bike back when it came out) and my 77 400 mainly, and I have leaned on my 400 pretty hard to get it to run as well as it does. It has alot of porting work done to it, 40mm Bing and internal roter ign. To give you an idea a stock 400 runs a 185 main jet. My bike requires a 200. It will run with the big boys, but it does not have the torque they do. You have to ride it more like a 250, which I enjoy.

As far as the turning goes you have me somewhat stumped. I have no turning issues with that bike and honestly cant remember the front end EVER giving away on me. That being said I was also a Maico dealer in the late seventies and nothing turnes like a Maico. Maico's were a very front end handling bike, too much so for my liking. I would classify the MC-5's as a somewhat rear end handling bike, but wll short of a Husky. I feel they still turn well when set up right. Obviously, Im sure you have looked at the tire.  Some Dunlop's Ive tried lost all traction as they got just a little wear on them, espically in the mud. This happened on my 74 Penton 400.  I acually thought something was wrong with the bike.  People are flying by me and I felt as if I was on ice and they were on dry dirt. Later I even fell on a dry track from losing the front end. I thought I was forgetting how to ride!  I mentioned it to my dealer and he said the same thing happened to him with that tire. New Michilin, problem solved. It also could be a number of things all adding up. On MC-5's you need a pretty stiff seat to get up on that long tank far enough. I got some foam so hard from Al Buehner a while back I have to first drill a million holes in it! You also need pretty straight bars with those swept back mounts or you will not be getting up on the tank enough. I use Renthal Mini High bars with that mount, yea mini bike bars, they are very straight and a nice bend.  A little narrow, but no more narrow than modern MX bars. I can get you the number if you wish. Once you get the bike set up as I mentioned you will be getting up on the tank to the point that the pegs will feel too far back, at least thats what happened to me with a stiff seat and the Mini high bars. I welded peg wideners on the pegs that were 1/4 inch to 1/2 inch wider using a spacer in front of the peg, efectivily moving the pegs forward. Helped alot.  Or you can get a 77 frame with the duel peg mounts and run them in the forward/down position.  Thats even better. I know of one of those frames for sale.

Dont give up until you have tried these things. I have the option of racing my 77 400 or my 80 420(or 495 for that matter as I have a 495 cylinder that bolts right on but I like the 420 better)but I would say on about 50% of the tracks I have an equal atvantage on my 400 due to it being so short, low and flickable compared to the 420 or even a 490 Maico. That being said if your talking about riding a full on modern track you would have to go with a bike like a 490 Maico or 420/495 KTM. Most of the post vintage tracks we race on are no so. If its a modern track we are routed around the hairy jumps(= more turns)...and I dont care to do the modern high flying act anymore anyway. Its still fun...as long as you dont screw up! Im too old to hit the ground that hard anymore!!

[tomale]

Mike had emailed me about the idea of making my MC 5 competitive again. The addition of travel at least for me was not an issue because there is really only a few times a lap where I would really use that extra 2 inches of travel. Several years ago I went to a S12 on that bike and boy what a difference it made. my lap times went up immediatly. I have just rebuilt the rear shocks so getting another set is out of the question but I was talking to a machinist friend of mine who built me a new shock shaft about the idea of building some new shafts 3/4 inche longer to allow for a longer shock. On these shocks this would not cause a problem because there is plenty of room in the shock body already. As for the front forks. As I understand it, improving the slow corner turn ability is a major concern and going to a set of 38 mm forks would help. I believe that part of the problem is that the 35mm tubes are just too thin and they flex too much.
A couple of months ago a friend of mine has been building a new bike and he could not get it to turn very well which is strange since it is a Maico.. On a lark he switched out the seat to a stiffer seat and Wam. the problem was solved. I believe on longer travel bikes having a stiffer seat is important because you need to be able to get farther up on the seat to over come the long travel in tight corners...The other thing I see alot of riders do is coast into a corner, they may brake hard but then they coast for 20 feet, when you do that you allow the front end to come back up and you loose the steeper angle of the forks that allows it to corner better. The other thing is that I set up my forks so that they are kind of soft for the first couple of inches of travel and then by using more fork oil I set them up to not bottom  out on the big stuff... The soft setting allows them to track better in the ripples and allows them to set up in tight corners with out having to sit on the gas cap but I do not loose the long travel for the big jumps.. I quess I am say it is just like a modern bike.. you need to set up the bike for the correct sag.. So at least for me as soon as I can free up some money I will be looking to update my 76 MC 5

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

[tooclose racing]

quote:Originally posted by pketchum

Brian/Mike,

The Renthal Mini-High bars are model 757-02 if I recall correctly.  I am sure of the 757 number since I remember it as a plane.

Also, if interested I have a couple of spare sets of 38mm Marzocchi's that have been rebuilt with new seals/paint.


Phil

Great discussion about the MC-5 and making it work!  Not sure if I'm ready to pull the trigger on some 38's yet (I too would need forks AND triples), but I definitely knew I had to do something about my bars and their current bend.  I'm pretty sure I have original bars on my '76.  I never thought of running with a Mini-Bar.  

Brian K.- your observations are interesting because of your CC experience.  I'll do some CC for the first time with the "5" next year and know this is going to be a very different animal than my Point-and-Shoot Six Day in the woods.

If you've seen the vintage photos of Moiseev on his KTM in late 70's, the fact that he had the factory mount a NON leading axle (long travel) fork must suggest he was having a problem getting these bikes to turn also.  []

[Doug Bridges]

There is a 76 MC5 rolling chasis for sale on ebay, and I thought it was interesting that the leading axle had been reversed to a trailing axle by flipping the fork legs around backwards. I wonder how well that works.

Doug Bridges
73 Jackpiner
74 Jackpiner/FrankenPenton project

[Britt Boyette]

The other thing Doug and I wanted to know about that roller is the lower frame mount. There isn't any.
Why is it that some MC5's seem to have the lower middle frame attachment while others do not?

Here's the link to the bike in question.
http://cgi.ebay.com/ebaymotors/1976-PENTON-KTM-MC5-250-PROJECT-w-MARZOCCHI-HI-POINT_W0QQcmdZViewItemQQhashZitem3ca6cca2aeQQitemZ260496466606QQptZMotorcyclesQ5fPartsQ5fAccessories

Britt Boyette
1976 125 MC5