CMF swing arms/100cc stuff

[brian kirby]

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

[firstturn]

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

[brian kirby]

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.



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

[john durrill]

Ron,
 I common friend [] 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.

[brian kirby]

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

[pakala]

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)

[brian kirby]

Nah, dont bother measuring anything Paul, I'm just brainstorming.

Brian

[VICTOR MONZ]

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]

[OUCWBOY]

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

[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
------------
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?

[Dwight Rudder]

quote: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

[FrankenPenton]

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:



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?

[brian kirby]

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

[454MRW]

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

[Dwight Rudder]

Hercules panel goes on the other side.
Dwight