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!
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
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!!
Quotequote: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
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
Brian,
Sounds like you need more weight on the front end.
I suggest peanut butter & hot fudge sundaes.
[B)]
Bob
Bob,
Funny you mention that, Ernie tells me the same thing. :D
Brian
'72 Berkshire
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.
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
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
Quotequote: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
Hi Mike, I have an interest in the frame you talked about here. Thanks, James
Quotequote: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!!
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)
Quotequote: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. [8)]
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
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
The lower frame center mount where not always use. These frames are for 125-175-and I have seen some 250's that don't have the middle mount.I know that you don't want to put a 400 motor into a frame without a middle frame mount. Hope this will help Later Gary
Doug,
"flipping the fork legs around backwards. I wonder how well that works."?
It doesn't...and do not ask me how I know[B)].
Ron Carbaugh
Quotequote:Originally posted by G Ellis
The lower frame center mount where not always use. These frames are for 125-175-and I have seen some 250's that don't have the middle mount.I know that you don't want to put a 400 motor into a frame without a middle frame mount. Hope this will help Later Gary
So it's alright to install a 250 into a 125/175 frame?
Britt Boyette
1976 125 MC5
Actually, I have a 76 MC5 chassis that was originally a 400 Penton that I have just installed a fresh 76 400 engine into this week. it never has had the lower engine mounts and I don't plan on racing the bike with the exception of maybe a future Reunion Ride or similar event, so I don't plan on adding the mounts. I have seen more 76 MC5 frames without the lower center mounts than those with them, and I have a few 76 MC5 chassis.
The 125/175 chassis will accept the 250 or 400 engine, but the central exhaust mount tab has to be removed on the frame to install a 250/400 pipe. The 250/400 frame has the rear exhaust mount at the back of the frame beside the seat, but the 125/175 frame does not have a rear exhuast mount, instead it is near the airbox on the inside of the frame by the right hand upper shock mount. Mike
Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S
On the topic of why some MC5 frames have bottom engine mount brackets, but the major majority do not - I thought we sorted that out one day, but I can't remember what the group's conclusion was.
It has nothing to do about them being for 400's though - I know that for a fact.
Unless they were on the very earliest 400's - because they're not on the later ones.
So, if your going to install a 250 into a 125/175 frame, you either have to cut off an exhaust mount or have a custom pipe built. Other than that, it should be fine?
Britt Boyette
1976 125 MC5
Quotequote:Originally posted by rob w
On the topic of why some MC5 frames have bottom engine mount brackets, but the major majority do not - I thought we sorted that out one day, but I can't remember what the group's conclusion was.
It has nothing to do about them being for 400's though - I know that for a fact.
I sure wouldn't want to take on rocky terrain without having something extra down there.
Britt Boyette
1976 125 MC5
I checked my chassis and spare frames this morning and have a total of 8-76 and 77 MC5 frames, which only one of them is a 125/175 chassis, and none of them have the bottom engine mounts. I always felt that they were omitted not only to save weight, but to make engine changes easier in the highly competetive motocross racing that they were aiming for at the time.
You can install a 1981 exhaust pipe with the stinger type removeable silencer without removing the center pipe mount bracket, but you have to use a 78 mc5 gas tank with the forward mounted petcock to clear the bigger design torque style pipe, or cap off the LH petcock on the 76/77 MC5 gas tank. I would sell one or two of my extra frames for $75 plus parcel post of around the same if you need one. I also have 78, 79, & one 1980 frame. Mike
There is a 125/175 frame on eBay right now # 300367971135. you can see the center exhaust mount bracket in the 2nd pic if you enlarge the photo.
Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S
Mike give me a call,I would like a MC5 frame. Later Gary
Ron I would like to know about flipping the fork tubes.:D:D:D Later Gary
that is interesting about the lower center engine mount, On both of the 76/77 MC 5 frames that I have, both of them have the lower mount. Same is true of any of the HareSramblers I have ever worked on too...quess I do not understand why some frames would not have them....not that I need to, not that it would make any difference. True it would make swaping out engines alot easier. Seems to me I heard story about a certain Penton ride at a ISDT event, had to replace a piston and did it in 15 minutes or something like that, that is pretty fast, I have taken the top end off my KTM and I never did it in faster that a couple of hours....but then I could never swap out a tire in under 30 minutes and even at that I thought I was doing pretty good...
Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)74'
250 hare scrambler (project bike)
Sounds like a Carl Crank story, maybe? Some people are awesome when it comes to changing tires, I'm on the other end of that spectrum. I do it but I hate it and it always takes a really long time.
The reason the lower bolt question popped up is because I'm considering such a swap with the 125. I'm thinking about installing a 250 and storing the 125 engine on a shelf. I really want a MC5 250.
Britt Boyette
1976 125 MC5
You would be better off, financially wise, to get a 250 frame and switch all of the major components to the new frame. They are all interchangeable, except the pipe and smaller carb, boot, throttle cable, choke cable, and possibly clutch cable, and you wouldn't have to worry about either modyifying your stock frame, or finding an 81 pipe and 78 MC5 tank for the pipe to work with the tank. You could then store your engine and original frame and use everything else.
If you would rather find an affordable 76 MC5 250, I have one that I have rebuilt the top end with a NOS 1st over piston, but can't seem to come up with a perfect enough set of wheels, cables, correctly jetted carb, etc, and it has sat all last fall and this summer waiting for me to finish it for around $1500. I do have wheels, but I am just too darn picky for my own good, and hate to build any part of it shoddily. It does have the repainted and installed airbox and an NOS carb boot, rebuilt and repainted Marzocchi forks, rebuilt stock Marzoccki shocks, freshly painted frame, swingarm and engine and very nice pipe. I have the correct carb that came on the engine, but it didn't run right at full throttle on another engine and I haven't determined why yet. The Motoplat hasn't been installed yet. I just need a good reason to finish it. if it was completely finished, I would expect it to be a $2500 bike easily.
I guess I have put off finishing it because if I can manage to get to tax refund time, I probably wouldn't need to sell it to satisfy my prior committments. Mike
Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S
I would have to sell this one if I were going to buy another MC5. It's all about the money kinda thing.
Britt Boyette
1976 125 MC5
I have read about why Moiseev (spell?) ran the 7-8 inch in line forks. He felt the geometry of the bike would change too much with more travel, causing the bike to not corner as well. I dont believe it was a forward axle verses non issue, it was more of a travel issue. For the tracks back then, and as I have asserted, for more tame semi modern tracks as we race post vintage on here in the midwest, less travel and the shorter "historic class" bikes can actually be an asset. Its cornering verses jumping when you talk suspension travel. Maybe I should shorten my travel up to 7 or 8 inches...to win!! Now thats a different thought!!!
I have never seen an MC-5 frame with the lower motor mount. No problem for 400's as long as you keep your mounts tight and are using 76 or newer cases with the newer style left engine strut mount. The old cases can break there in an MC-5 frame. I believe I was told way back when it was a frame flex issue as to why they were left off. All I ever raced were 400's, in MX, concerning the MC-5's, no bottom mount is not a problem. Some of the 77 GS-6 frames have the lower mounts. Probably for log bashing as one of you mentioned. The 77 GS-6 frames are basically the same as the mc-5 except for the frame breather aspect and a rear fender loop. A better set up it would seem to me for CC racing. By the way I have an extra 77 GS-6 frame if any interest.
I purchased the bike with the backwards forks (and dual mount pegs). However, if James or amy one else wants a 77 dual peg mount frame, the same guy has another one with a 400 engine in it. Actually, the deal I made with this guy was I could have either one if the other one was still not sold when I go to pick it up the first weekend of Dec. However, if any of you really want one bad feel free to purchase the other one now, someone else may at any time. Otherwise, I will look them both over at that time and report back on their condition. The one I purchased is # 260496466606. The 400 is # 260496466937.
Britt, having a MC 5 sale this month only ;250s 400s a 175 frame and more! LG
LG,
Are you up already? It's only 10:50 AM and I hate to call you before noon after a hard night of eBay/Craigslist!
I was afraid I'd wake you up and was going to call you an hour ago. JP needs to find a rod kit for my motor. Do you have one? How about Mark Biro, or maybe Jake Fisher?
Call me later if you can. I'm going to flat track tonight.
Clay