Penton Owners Group

General Discussion => Penton Talk => Topic started by: brian kirby on April 25, 2008, 12:39:58 PM

Title: CMF swing arms/100cc stuff
Post by: brian kirby on April 25, 2008, 12:39:58 PM
I know the Sachs and KTM engine frames have different motor mounts but do the swing arms swap? Is there any advantage to using a 74.5 swing arm on an earlier CMF frame if you are not going to use the "lay down" shock mounts?

Also, a while back we were talking about 100cc hop-ups and we discussed the "Cranke" pipe mod. I know Cricle-F has Penton 125 pipes but does anyone know if Kevin can or does make a 100 spec pipe? Seems like if we sent him the "Cranke" specs he could make a 100 pipe with few modifications to his 125 pipe. I guess I need to call him.

Brian
Title: CMF swing arms/100cc stuff
Post by: firstturn on April 25, 2008, 01:49:07 PM
Brian,

"I know the Sachs and KTM engine frames have different motor mounts but do the swing arms swap? Is there any advantage to using a 74.5 swing arm on an earlier CMF frame if you are not going to use the "lay down" shock mounts?"

The 74.5 is a Sachs engine and will fit the earlier frames with the main difference being where the kickstand mounts.  I see no advantage if this is the question?

"Also, a while back we were talking about 100cc hop-ups and we discussed the "Cranke" pipe mod. I know Cricle-F has Penton 125 pipes but does anyone know if Kevin can or does make a 100 spec pipe? Seems like if we sent him the "Cranke" specs he could make a 100 pipe with few modifications to his 125 pipe. I guess I need to call him."

Circle F made the 125 pipe at our request and it can be made to work on a 100.  I took him the pipe and bike for him to make a jig and we made the current pipe to fit all the Sachs powered Penton CMF frames including the long travel. I feel that Kevin (Circle F) has his hands full with other pipes at this time and probably would prefer to not having to build another Penton pipe(since he builds other brand pipes also)....just my thoughts as he is normally running 6 to 8 weeks behind and really is a one man operation.


Ron Carbaugh
Title: CMF swing arms/100cc stuff
Post by: brian kirby on April 25, 2008, 02:03:47 PM
Thanks Ron. I have access to a 74.5 Jackpiner carcass and I didnt know if that style swing arm was better (longer, more rigid) than the early swing arm. I guess you are saying that other than the "lay down" mount they are pretty much the same as the early swing arm? The lower shock mount has been moved up a few inches by the original owner, but it was done cleanly and with the right shock should work fine and be AHRMA legal for shock travel.

I have not seen the bike in person but it appears it might have the Cranke pipe mod done on the original pipe.

(http://www.the-gunfighters.org/Berkshire.jpg)

Ernie's bike has a Circle-F pipe and it really "barks". As long as the pipe Kevin makes now will work for a 100 its no big deal. By looking at his pipe the belly seems smaller than the stock pipe and appears to be a mid-high pipe which is what I want for the 100.

Brian
Title: CMF swing arms/100cc stuff
Post by: john durrill on April 25, 2008, 02:24:16 PM
Ron,
 I common friend [:p] provided me with the 74.5 swing arm for my bike when I went to the lay down shock mounts. I had some time to play with both style swing arms the only difference I found was the rear brake stay mount was 1 and 1/2 inches farther forward than the multi lower mount swing arm. The shock mount was in a different place but everything else was the same.
 Brian were you looking for the extra gusseting for strength the 74.5 and up KTM swing arms have? It is wider and heavier than the swing arm you have. I have one stripped in the garage and a CMF 100/125 arm. I can compare them and send you the measurements if you need it.
 We made one of the Carl pipes a few years back. Its one straight section and one cone and a stinger. You could get a local sheet metal shop to roll the 2 parts. I think emt would work for the stinger.
 It not hard to make the pipe up , it just takes time fitting and tacking. once you have the parts tacked its a quick job to weld up.
 Anyone can do it that has a little time on an oxy accet rig.
 I did and my total training in welding was 10 mins in 1969 when someone showed me how to set the flame up for sheet metal repair on a pipe chuckle chuckle!
 John D.
Title: CMF swing arms/100cc stuff
Post by: brian kirby on April 25, 2008, 02:59:25 PM
John, I was not really looking for anything, just tossing out the idea of the pros and cons of the 74.5 swing arm. I should just leave well enough alone and not try to fix something that aint broke.

Brian
Title: CMF swing arms/100cc stuff
Post by: pakala on April 25, 2008, 04:16:34 PM
Brian,
 The pipe on this Berkie has been modified. I don't know if it is Cranke specs. It is diffrent than my other 6day pipes. I could take some measurements of the pipe if you like?
 This Penton 100 was raced in Socal back in the glory days,Saddleback adobe can still be found in her crevices. This Penton needed to be campaigned. In my hands it could of only been a pit bike, but under Baby Brian they become a terror and with his Uncle Ernie on his Penton 100 they become a one two punch! Watch out Rat boys the little Red Sleds are coming!
                 Paul(socal)
Title: CMF swing arms/100cc stuff
Post by: brian kirby on April 25, 2008, 04:39:50 PM
Nah, dont bother measuring anything Paul, I'm just brainstorming.

Brian
Title: CMF swing arms/100cc stuff
Post by: VICTOR MONZ on April 25, 2008, 04:58:28 PM
I have a 100 cc pipe built by METTCO to the 100cc Carl Cranke specs which were published a few "Still Keeping Track"'s ago, it has no silencer at this time, straight pipe...intimidating!.....I may be talked out of it for the right sales pitch? ($).

Victor Monz

[email protected]
Title: CMF swing arms/100cc stuff
Post by: OUCWBOY on April 25, 2008, 06:53:44 PM
Brian,
The Jackpiner swingarm will not fit the Sachs frame. I have a 74 1/2 that does not have the lay down position. It is my understanding that the 125 that Circle F makes works just fine on the 100.

Donny Smith
Paragould, AR
Title: CMF swing arms/100cc stuff
Post by: FrankenPenton on May 12, 2008, 04:34:17 PM
Not to change the subject, but...

...the numberplate/side panel on the bike pictured above looks unusual - what model is that?




Brad Webster
Houston, TX
------------
assorted aftermarket parts, with a front end, wheels, and Berki motor from a steel tanker, all stitched together in a '72 CMF frame, then buried alive for a quarter of a century...  can it live again?
Title: CMF swing arms/100cc stuff
Post by: Dwight Rudder on May 12, 2008, 04:46:35 PM
Quotequote:Originally posted by FrankenPenton

Not to change the subject, but...

...the numberplate/side panel on the bike pictured above looks unusual - what model is that?

Brad Webster
Houston, TX
------------

1974
Title: CMF swing arms/100cc stuff
Post by: FrankenPenton on May 12, 2008, 08:52:41 PM
I've looked in the POG gallery and didn't see any like the one above.  The most similar type I've seen is like this one:

(http://www.pentonusa.org/photos/2003/vintagedays/bikes/regviews/dsc03858.jpg)

There are quite a few of this type, which has the triangle shaped part starting behind the tube at the front, and the frame tab it's bolted thru is on the front of the tube.  The bolt goes thru a part of the oval that extends past the front edge of the triangle, and the triangle is not continued below the oval.

That panel on the red bike wraps around the tube at the front, and it seems to be bolted thru the frame tab that's used for the airbox, behind the tube.  The oval shape doesn't extend forward past the triangle shape, and the triangle shape is continued below the oval.  Could it be aftermarket, or special made for a race team, or is the reb bike above an unusual '74 model that's not shown in the gallery?
Title: CMF swing arms/100cc stuff
Post by: brian kirby on May 12, 2008, 09:06:01 PM
The Berkshire above is not a '74 although it looks just like one, its frame number is 20756420 so that would make it either a late '72 or an early '73. It does appear to have many '74 parts like the tank graphics and the black painted mag wheels but I bet those were added later. It has 32mm forks, which I think all the '74s had 35mm forks? This bike was ridden by a SoCal racer and has been modified (look closely at the lower shock mounts) so I would guess that side panel is not stock. Maybe some kind of period aftermarket part?

Brian
Title: CMF swing arms/100cc stuff
Post by: 454MRW on May 13, 2008, 12:33:41 AM
It looks like the side panel for a Hercules, similar to the Blue one that I delivered to Ric Emmal at the 2006 Reunion Ride, Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S
Title: CMF swing arms/100cc stuff
Post by: Dwight Rudder on May 13, 2008, 01:43:34 AM
Hercules panel goes on the other side.
Dwight
Title: CMF swing arms/100cc stuff
Post by: socalmx on May 14, 2008, 01:07:27 PM
I hate to burst anyone's bubble but during the SoCal glory days, it was not a Penton sweeping the 100cc class. Sig Erson's (of cam fame) son raced a Honda SL100 and ruled Ascot, Lion's Dragstrip, etc. I always suspected that it was a cheater and was pumped out to around 150cc but never found out for sure.
Title: CMF swing arms/100cc stuff
Post by: firstturn on May 14, 2008, 03:11:19 PM
Sig never showed up in Texas so it was 100 Pentons that were winning in the Glory Days of Texas Moto X [:p].  I have helped build some of the little Honda way back when and they were fast especially with a  light rider.

Ron Carbaugh
Title: CMF swing arms/100cc stuff
Post by: socalmx on May 14, 2008, 05:05:33 PM
I started out on a 1971 SL100 and did all the usual tricks:
Opened up intake and exhaust ports
Ground down the rocker arms
Hi lift cam
High compression piston
Honda 305 carb mated to a Webco mainfold
Filtron "sock" aircleaner
Bassani megaphone exhaust system
Lengthened swingarm
21 inch front wheel
Curnutt shocks

Darn thing made a lot of noise but still could not keep up with the two strokes. What was interesting is that Honda built a special four stroke 125 for Bruce Baron to race at Ascot against the Mettco boys. It was a very pathetic mis-match.
Title: CMF swing arms/100cc stuff
Post by: firstturn on May 14, 2008, 05:20:43 PM
socal,
  We had a lot of tricks for the 4 strokes and I saw some at the Factory after I went to work for Honda that I had never seen before.  It is call liquid money.  All of the old days of racing was great.  One of my best Friends had a fit out running the 125 Bultacos with his Elsinore.  He did beat them, but it was a catch them in the corners.  Years later I was visiting with a old factory wrench who told me that the bike (Bultacos) were 175cc.  We had a good laugh at how the riders couldn't even beat my Friend with a 50cc advantage.  Great memories.

Ron Carbaugh
Title: CMF swing arms/100cc stuff
Post by: Chakka on May 14, 2008, 07:25:45 PM
Ron,

What years did you work for Honda? I am taking a temporary breather from Penton's to put together a Honda XR75 out of nostalgia...I can still remember my dad pulling in the driveway with a silver XR in the back of his pickup. It should be a fun play bike and my little niece will love to race around the yard on it.

Chris
Title: CMF swing arms/100cc stuff
Post by: firstturn on May 14, 2008, 09:33:42 PM
Chris,
  1978 - 2002

Ron Carbaugh
Title: CMF swing arms/100cc stuff
Post by: tmc3c on May 15, 2008, 08:58:18 AM
Chris,
     My brother used to flat track a XR75. My dad did a little bit of work to the motor. I think he changed the cam and carb and if I can remember right added a battery. Also, of course a header by JR I think,small rear tire so he could reach the ground. That bike was fast,I seen it out run a stock 100cc in a straight line.



    The Kawasaki Green Streak also used to be a force in the 100cc class here in S.C.



Thomas Carmichael


1970 125 Six Day
1976 250 Hare Scrambler
Title: CMF swing arms/100cc stuff
Post by: socalmx on May 15, 2008, 11:16:46 AM
Do you mean the Kawasaki Centurion?
Title: CMF swing arms/100cc stuff
Post by: Steve Minor on May 15, 2008, 12:15:00 PM
See this site

http://www.theowencollection.com/70Kawasaki.html


Title: CMF swing arms/100cc stuff
Post by: tmc3c on May 15, 2008, 04:28:57 PM
Socal, Yes, I mean Centurion. I don't know why we didn't call them that back in the day we just knew them by Green Streak.

Thanks for the link Steve!!



Thomas Carmichael


1970 125 Six Day
1976 250 Hare Scrambler
Title: CMF swing arms/100cc stuff
Post by: socalmx on May 15, 2008, 05:36:06 PM
They were fast bikes but rather flimsy and tinish. I had a friend who raced one at Ascot MX back then. He put a down pipe on it but could not figure out why it kept getting pulled out from the cylinder after each jump. Turns out he had wired the pipe to the swingarm which you could say did not work too well. I also had a friend who took a 100 cc (trail boss?) no Centurian engine and put it into a Rickman frame and raced desert on it.
Title: CMF swing arms/100cc stuff
Post by: tmc3c on May 15, 2008, 08:29:56 PM
Socal,I was asked to flat track one for a guy in Orangeburg S.C. He said he wanted out front at all cost. I remember running it as hard as I could into the corners that the front tire was hollering. The best I could do was 4th. I remember the big plush seat and those HARD grips and that mesmerizing lime green tank!! Sorry for the rambling I am back now[^]



Thomas Carmichael


1970 125 Six Day
1976 250 Hare Scrambler
Title: CMF swing arms/100cc stuff
Post by: 454MRW on June 04, 2008, 05:29:07 PM
Dwight,
Check out the 2nd pic on this eBay listing for a 1978 Hercules. The right hand side panel is shaped very similar to the one on this bike with the exception of the numberplate positioning, and like I mentioned, I think it was off of a Hercules and trimmed where it is flared out for shock clearance to provide exhaust pipe clearance in this case, but probably just not this particular year model. Mike
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=180250094596&ssPageName=STRK:MEWA:IT&ih=008

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S
Title: CMF swing arms/100cc stuff
Post by: brian kirby on June 04, 2008, 05:36:51 PM
I agree with Dwight, I dont think its a Herc side panel. If you look at the side panel on the Berkshire althought it has been trimmed you can see the bulge for the Penton right side exhaust, not the left side like the Herc. I think its probably a trimmed aftermarket side panel.

Brian
Title: CMF swing arms/100cc stuff
Post by: FrankenPenton on June 05, 2008, 12:50:23 AM
Here's another one I found:

(http://i24.ebayimg.com/01/i/07/5c/e0/be_1_b.JPG)

Item# 270015764677 - seller says it's from a 1972 Penton 125cc Six-Day ENDURO, Frame# 20957473, Sachs# 7176349

Were all bikes set up the same from the factory, with enduro "kits" being sold separately or dealer-installed, or were different versions factory-produced?



Brad Webster
Houston, TX
------------
assorted aftermarket parts, with a front end, wheels, and Berki motor from a steel tanker, all stitched together in a '72 CMF frame, then buried alive for a quarter of a century...  can it live again?