1975 model year

[Larry Perkins]

Ted,

Kobe; and I think I am spelling it right, had hardened chromed shifting parts and adjustment instructions that took into account the fact that MXers tend to shift harder on the upshift than on the down side.  I have not seen one of these kits in a long time.  You could have the parts like the selector key chromed.  The selector rod is already like that when new.  The trouble is the key was designed to wear and when it doesn't then there are more gear troubles down the road than with the stock key.  I think if you adjust like the Kobe and replace the key fairly often and have a good selector rod it will be as optimum as the design allows which is far from perfect.  That is a big reason they allow such a new bike in Classic class.

I think gearing can range somewhere between 12-52 and 13-64 depending on track.  I like gearing better with the 13 countershaft sprocket because it does not wrap the chain up too tight.  The chain throw problem is lessened.  Be sure and run a case protector with these bikes if you race them you will save cases sooner or later.

Chadwick?  I would sure love too but I am supposed to go watch 4 of my pigeons race in Oklahoma City this weekend.  It is a Futurity Race with about $10,000 prize money.  Now everybody knows I am a freak.  Just another one of my hobbies guys.  If I don't go Ted, I would love to show you guys around some of my favorite parts of Chadwick.  If not then another day.  Thanks for the invite.

 

[Mark Annan]

I have the pictures, but no scanner at the moment.  I'll see if I can get my wife to take them to work and scan them for me.  From what I can see in the picture it looks like the bike still uses 32mm forks, I thought it would have 35's.

 

[OUCWBOY]

Hey guys,
A note on Larry's commit on the chrome shifting key........If you have it done, make sure you find the best chrome guy around. Nothing worse than the chrome peeling off and messing up everything else. This happened to us a long time ago. Chrome pieces in the bearings are not too good. However, if they are done properly, they should not peel and will help with the shift key wear.
Donny

[imported_n/a]

Larry, as part of your "Fastest and Most Reliable" recommendations, what is your preference for the carb?  I don't know what the "D" engines came with or what they were fitted with for optimum breating.

Glenn

 

[Larry Perkins]

I always forget some things.  Age and too much fun will do that.  

The 28mm newer style Bing(Type 84) is what most of those used.  There are two types and two types of cylinders.  The slide over type with the fiber throat bushing and the pop in type.  

The best set-up is the cylinder that has the rubber mount that looks like a Mikuni mount.  This requires the pop in spigot mount Type 84.  

The next best thing is a reamed out spigot to match the 28mm better with an aluminum sleeve over it so the slide on Type 84 will work.

You can run a 30mm but it is alot more work down low and I think most of the ones that did had the boost ports in the back.

Okay now I will put in the parts plug since it relates.  Sorry always the salesman.  I have some of these carbs used and several NOS shells.  Also have one real used cylinder that will need a sleeve soon of the type with rubber spigot carb mount.  In case anyone desires them.

 

[john durrill]

Larry,
 do you have one of the old instruction sheets from the kobe shift kit?
 If you do i would like to get it posted in our Library.
John



Edited by - john durrill on 08/27/2002  09:24:48 AM

[imported_n/a]

Larry, do you mean that running a 30mm causes a shorter powerband than the 28?  I've got a like-new 30mm Mikuni that came on my junker Jackpiner (the owner thought it needed a new carb, but it was the Motoplat!)
I have a slip-on adaptor for the Sachs cylinder to fit the bolt-on carb.  Do you have any experience with the Mikunis?

 

[Larry Perkins]

John, I don't have any of those instructions but basically instead of adjusting throw even on the up and down you adjust with less throw on the upside.  I think Doug Wilford could perhaps explain it better and confirm my thinking and memory.  He is the master.

Glenn, I think the larger the carb the more top and less bottom.  I know it begins to be harder to ride and more clutch work is necessary.  Of course clutch feathering is a part of HOT 125 racing both back in "The Day" and now.  John Durill has more the rocket science brain and could explain the physics of this and confirm whether my thinking is right.  John?

 

[john durrill]

I have Trouble walking and chewing gum at the same time guys.  chuckle chuckle
 so my rocket science would look like the first days of Nasa trying to get a satellite in orbit!!!!
 Your Right Larry,
 The larger you go in bore size on a carb the less vacuum you have at lower RPM"s. the Carb doesn't meter as well and it makes it harder to ride at low rpm settings.  the transition between circuits in the carb is not as smooth.
 I had a big single Honda street bike ,a GB 500 that we bored out to 600 cc . it came with a 42 mm Kehin CV carb. I Need to change the carb and got a 40mm Mikuni RS. thought it was smaller so it should run fine. The guys at Sudco tried to talk me out of it and into a 38 mm. the 40 mm RS flows like a 44 mm CV.
 well the upshot was I never could get the 40 mm RS to run right. I would have had to change the cam  for a full race one to get it to work . that would have made it a bear to drive in town.
 Now if the 125 Glen has was reed kitted with a reed off say a 250 now then the 30 mm would work fine I think. the reed would allow you to run a bigger carb and not loose too much in the bottom and mid range.
 the stock 27 and 1/2 works good. and 28 mm mikunis work good on the 125.
 skipperclyde has one on his sons 125 sixdays and it runs great. he can give you the jetting info and how he addapted the intake and air boot so it fits right .
 John & Peter

 

[Larry Perkins]

Be aware that with AHRMA if you use a reed valve the bike automatically becomes a Sportsman class bike and is no longer a Classic class bike.

 

[Rocket]

I have a 77 100, Sachs motor, that has 3 shock mounting holes in the frame and 3 on the swingarm.
Rocket

 

[john durrill]

Rocket,
 It sounds like you have the very best Sachs engine powered Penton / KTM made. the reliabillty of the little Sachs motor. the good power it makes with long time between rebuilds . And all the travel front and rear most folks need to run enduros and trail ride.
 i would hang on to that one.
John

 

[Rocket]

John
I believe the 77 100 will be a keeper for my collection, seems like it may be a rare animal!!
Rocket

 

[imported_n/a]

Larry, do you have the LA Sleeve part number for the D GS sleeve?  I e-mailed them and they were drawing a blank without a part number.  

Thanks.

 

[Larry Perkins]

Glenn,

I think I have a couple yet.  I don't know if they still make them.  E-mail me Monday to remind me to look.