I have a question for the POG collective mind:
I picked up a late 73 Hare Scrambler rolling chassis from Mike W. (thanks again Mike), motor is a 74'ish 250. I have stripped and re-painted (self etching primer, silver, 2 part clear coat).
I am not going for a restoration, I set all my bikes up to look close to period correct, but they must be stone reliable and its ok to take advantage of any technological advancements (new ignition, Race Tech springs, etc). My riding abilities preclude me from taking advantage of 100% of the bike anyway (translation: I am slow and I fall down alot, but I love doing it.)
My question is do i need to grind the motor mount pads, coil mount pads back to bare metal in a small spot for good ground?
Or run a separate ground wire from the coil mount area to the stator plate?
Or both?
Pictures of the progress so far:
(https://i33.photobucket.com/albums/d89/AJ67SS/Pics%20for%20Web%20Pages/20190316_150035_zpsv6zeddjj.jpg)
(http://i33.photobucket.com/albums/d89/AJ67SS/Pics%20for%20Web%20Pages/20190324_163144_zpswwfit62t.jpg)
Edit: While cleaning up my Photobucket account, I thought I would see if I can get the images to work with the posting again.
And I took your advise and cleaned the physical connections between the frame, motor and electrical components, checked for continuity and ran a separate ground wire.
Thanks,
Andy
#14u
MOVMX, AMA, AHRMA
Hello and sounds like a very nice project I ran into an ignition problem on a Husqvarna 390 auto when I had the frame powder coated. I ended up doing both to be on the safe side and all was well. I think you would be safe with cleaning contact areas but for competition I would add a ground strap too.
The coil mount is all that needs to be bare in my Penton experience.
Larry P
I would take off all paint, motor to frame that touch each. Also run a heavy wire from frame to top of the cylinder. This helps with ground, if you do this will not have any trouble.
Thanks Ron, Larry and Gary for the help.
I plan to do just as Gary outlined.
One last pic for now...
(https://i33.photobucket.com/albums/d89/AJ67SS/20190323_153335_zps99bmqqmc.jpg)
Andy
#14u
MOVMX, AMA, AHRMA
Looking good and what brand are the rear shocks?
Ron Sherfy,Ohio 1974 Penton Berkshire 100 1994 ATK 406 1976 Honda mr175 1974 Honda mt250
Those are Curnutt shocks.
Larry P
Larry is correct, Curnutt shocks.
They work pretty well, easy to maintain, rebuild and tune.
The hard part is finding the right length and spring weight.
Andy
#14u
MOVMX, AMA, AHRMA
I had the coil mount crack on mine, I suppose from engine vibration. Some Penton machines came with a rubber insulator between the coil and frame so I made one after I got the frame welded.
I had the coil mount break clear off on my 74 250cc ! This was when it was about 2 yrs. old. I jammed a stick of wood under the coil to hold it against the mount! It got me home![^]
Our 1973 ISDT machines had dual coils, possibly the folks at KTM and Penton R & D knew they had some issues. I had always just figured they were concerned about coil failure, having never had a mount crack or come off I never gave that a thought.
We had a quick release set up on the tank strap that would allow for quick access to the coils to switch the wires without removing the seat.
I believe it was Dick Burleson who while working at the Husky building just a block or so from Penton R & D who told me of tearing a Husky race bike pretty much apart trying to figure out why there was improper spark, in the end it was a bad ground. If I remember right it was the engine contact to the frame where his issue was.
Paul
Continuing on with the build of a 1974 250 hare scrambler / racer, not a restoration. Made some progress, and incorporating alot of the ideas I read here. Going for as much reliability as I can get.
(https://i33.photobucket.com/albums/d89/AJ67SS/DSC_1123_zpsjcude75s.jpg)
(http://i33.photobucket.com/albums/d89/AJ67SS/DSC_1120_zpsdheaoyhd.jpg)
Andy
#14u
MOVMX, AMA, AHRMA
Looking really great Andy! Good to see my old bike coming back to life again, congratulations. Mike
Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Penton
1976 MC5 400
1978 KTM 78 GS6 250
L78-79 MX6 175-250 KTM's
1976-78 125-400 RM's
2007 CR125R Honda
1977 MC250 Maico
2017 KTM Freeride 250R
Thanks Mike. I appreciate the opportunity you gave me by selling me the project.
I am making some slow progress, because I have had to re-do several things over; just didnt like the results the first time around.
I did buy aftermarket red side covers, but after some deliberation this weekend, I dug out the hammer/dollies and worked the aluminum airbox cover that you included with the bike, back into shape. Fits perfect now.
I also pulled out the fiberglass repair materials, and started in with plans to re-glass the right side cover. I will make repairs on the backside using a combination of cloth, mat, and some chopped fibers, so I can re-use that original cover. The wear and tear on it looks great.
Not sure I will use it, but I liked the down low torque of my 74.5 Jackpiner so much that for this 250, I found a flywheel weight for the HPI ignition. Testing will tell which route I go.
(https://oi33.photobucket.com/albums/d89/AJ67SS/edited-image_zpsbaamphxq.png)
Thanks again.
Andy
#14u
MOVMX, AMA, AHRMA
Nice Ignition, where did you find the flywheel weights?
Raymond
Down East Pentons
I would like to mention here another important and overlooked part of an ignition ground path.
An Ignition stator ground begins (or ends) at the frame of the stator.
A painted engine case or oxidized stator adaptor plate will disrupt the ground path.
This will cause weak or no spark at all. make sure all mounting surfaces are free of paint/oxidation between backside of stator and engine case.
Rain Man I have them for HPI ignitions. I am a dealer here in the states for their product.
Thanks Jerry, and I am on it.
Gary also pointed out the importance of a good case ground on the ignition, so I will be installing a separate ground wire from the stator plate to the coil mount, stopping at a head fin along the way.
Andy
#14u
MOVMX, AMA, AHRMA
Anybody own a Fluke?
Thanks Gary, I've been wondering if they have that specific ignition for Jackpiners too?
Raymond
Down East Pentons
They are the same for all KTM Penton motors. I have them in stock.
She is looking great Andy keep up the good work and I can't wait see her competed. I am getting some inspiration for mine through your build so thanks for the motivation.
Ron Sherfy,Ohio 1974 Penton Berkshire 100 1994 ATK 406 1976 Honda mr175 1974 Honda mt250
Thanks for all the questions/comments, I do appreciate it.
I have made a bit of progress this last week, here are a few more pics and some of my own comments and a question.
I went with a 520 chain. The chain guide/slider will need some adjustment as it isnt centered.
I did the Mikuni conversion. I know, Bing is the Thing on Penton, but I have 4 other vintage MX/HS bikes and they all have Mikuni carbs. Given my history/knowledge base/spares, I went with the conversion.
I had to do some fiberglass repair on the side panel and tank, but I drain the fiberglass tank on the other bike after each ride, so I think it will be OK with this tank.
I am guessing that the 250 exhaust spring length is around 95mm. All of my spare exhaust springs are for Hodaka's and an American Eagle Geronimo, and are shorter.
The Curnutt shocks are getting a rebuild.
First start up was pretty easy, 4 or 5 kicks, so far it has started after that with one kick (4 short heat cycles, low rpm in first across flat ground). The motor rebuild seems excellent.
I am not sure I like the extra flywheel weight on the HPI ignition. I will pull it off and do a few more heat cycles to the motor, just to see the difference.
I have added a separate ground wire (ignition case, head, coil mount, all verified with a Fluke).
I need to work on the cable routing a bit to free things up and secure them from tree snagging.
Last one is a question:
How does the end cap come off the pipe on this bike? I dont see a fastener anyplace; is it crimped on?
(https://oi33.photobucket.com/albums/d89/AJ67SS/Pics%20for%20Web%20Pages/20190412_174039_zpsut3ameoa.jpg)
(https://oi33.photobucket.com/albums/d89/AJ67SS/Pics%20for%20Web%20Pages/20190412_174023_zpsattvcbts.jpg)
Andy
#14u
MOVMX, AMA, AHRMA
Build looks good. Just checking out those fork boots. Are they new and where did you acquire them. I am in need of a pair for my Hare scrambler. William
Some of the end caps were retained with a spring but I believe that one is tack welded in place, as were some others originally. Careful grinding at the seam, and possibly around where the perforated tube sticks through the center portion of the cap will be required. Mike
Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Penton
1976 MC5 400
1978 KTM 78 GS6 250
L78-79 MX6 175-250 KTM's
1976-78 125-400 RM's
2007 CR125R Honda
1977 MC250 Maico
2017 KTM Freeride 250R
OK, thanks Mike. I will take a closer look at the silencer this weekend.
William: I got the fork boots from Al Buehner. http://www.pentonpartsusa.com
Al also has a ton of parts that don't show up on his web page, so call and ask.
Andy
#14u
MOVMX, AMA, AHRMA
Thanks Andy and looks like it coming together for you. Those air cooled two fifty's are thoroughbreds. Good luck William
Ok, so now I have a question for the POG collective:
I put the Bing back on the 73 250 HS and it seems to run great.
But while gathering parts, I ended up with a few Bing 84's (and a 74/75 MX1 250 Can-AM).
Anyway, a couple of the Bing 84's have some sort of choke or other mechanism screwed on to the carb body. Can someone explain to me, or tell me where to find, what it is and how it works?
(https://i33.photobucket.com/albums/d89/AJ67SS/Capture_zpsqs2cpm9y.jpg)
Andy
#14u
MOVMX, AMA, AHRMA