New 125 6B rod kits

[Marc Biro]

With the ever increasing need for "new" Penton parts, I took it upon myself to reproduce the 6B 125 rod kits. These kits are made to a much higher standard than original, and carry a retail price of $110.00.

The rod itself is "I beam style" for greater strength all around, and allows you "high RPM/speed freaks" to increase HP without sacrificing reliability. The kit includes: rod, upper pin, upper bearing, lower pin, lower bearing and thrust washers. Kits are in stock! Dealer inquires welcome.

Thanks

Marc Biro
Builder of the 125 "METTCO Replica"

[john durrill]

Marc,
 Would it be possible to get a kit with a shorten lower pin? What would is cost to have that done? Having a pin shortned localy with out damaging the polish on the bearing surface and keeping the ends square is not easily done for most.
 How thick are the rod thrust washers?
The reason i ask is that this rod would work in 100/125 A , B and 175 engines. The 175 uses a thinner thrust washer .025 as apposed to the 125's .053 but the same rod as the 100/125 and the A rod a shorter pin buy about .060 to .065 as the kit you show.
 The 175 rod kits are very hard to find.
Thank you for you efforts,
John D.

[Marc Biro]

John D,

I had taken into consideration all the issues you mentiond prior to making the rod kits for the 6B motor. The actual lower rod pin length in my 6B rod kit measures 54.5mm allowing it to be used for either the A or B motor. With the 54.5mm length pin used on the 6B crank, it is 0.75mm shy from flush on each end of the crank halves, and do not cause any problems such as crank halves rotating out of balance. SACHS new what they where doing when they designed the pin/crank with a taper allowing for a very snug fit! I have run my kit on my personal bikes with great success. I am about 2 weeks away from receiving the 0.75mm thrust washers that you are requesting.

Thanks

Marc Biro

[Tony Price]

quote:Originally posted by Marc Biro

John D,

I had taken into consideration all the issues you mentiond prior to making the rod kits for the 6B motor. The actual lower rod pin length in my 6B rod kit measures 54.5mm allowing it to be used for either the A or B motor.
Thanks

Marc Biro

Mr. Brio,

You are a credit to Pentonkind.



Tony

[Lew Mayer]

Marc,
I've E-mailed you. Have you gotten it? How do we get these kits and how do we pay for them? Credit card? Money Order?
Thanks

Lew Mayer

[Mark Annan]

How does the weight of the new rod kit  compare with the original stuff?  Will it be necessary to rebalance the crank,rod,piston assembly?

Now we need a good supply of the main bearings.  

Thanks,  Mark

[Kip Kern]

Mark

You can get the  M-20 main bearings through Applied Industrial Technologies.  It is a standard 3 piece magneto bearing available at roughly $40 per copy the last time I looked.  I am sure that other bearing jobbers can get the same;)

[Marc Biro]

Mark,

I will weigh the kit tomorrow and advise.

Thanks

Marc B.

[Mark Annan]

Kip,

I think they have an office fairly close to me.  Do you have their stock number or some other ID number they may recognize.  Last time I tried to get a guy to look up a M 20 "magneto bearing" all I got was a blank stare.

Mark

[john durrill]

Mark,
 I don't think you would need to worry if the rod is a little heaver than the NOS ones.
 Here is what we found out from the 175 conversion on the 125 Sachs lower end.
 The Sachs and Penton engine repair manuals have a balance factor of 80 to 83 % listed as the thing to shoot for.
 Knowing the 175 Piston was 1 and 1/2 ounces heavier than a Sachs 125 piston we thought that weight would have to be added to the A crank we used. We contacted Falicon and went through what we had and what we needed. They recommended that a 60 to 70 % be used when building our a crank. That is a very big difference so we double checked with Martijn in the Netherlands on what his 125 Sachs Road Racer was balanced at. He confirmed what Falicon had told us. He is using a 66 to 70 % balance factor.
 We went with the balance factor Falicon recommended. Over 2 and 1/2 years  the crank has worked fine. No difference in vibration over the stock 125 Sachs or the 175 KTM engine in my sons Piner.
 Anyone else that has more experience with cranks or some better idea's Please offer what you know here. Doug , Ron, Bobby , Kip , anyone please chime in here. This is an important Bit of knowledge that everyone will gain from.
 John D.

[firstturn]

John,
  I will see if I can find my notes on the reed valve engines and other pistons that I have drilled.  I had to change to a B crank assy on the cut pistons(for port timing) due to cutting weight off the piston(making it lighter).  When I get time I will look it up, but I thought mine was around 72 to 74%(with the lighter crank)?

Ron Carbaugh

[BrianTaylor]

Mark when looking for the M20 Bearings it is best to tell the bearing supplier it s a "Consolidated M20 "   Consolidated is a bearing importer that always have them in stock ... Manufactures like SKF and FAG dont seem to keep inventory on these low use bearings . If you order a Consolidated you will probably end up with an FAG brand .
Brian Taylor ( OP MGR Canadian Bearings )

Brian Taylor

[Marc Biro]

Mark,

The weight of the new "I beam style "125 rod is 4.8 oz. Stock rod is 3.6 oz. Weights of all other components are the same. Once the kit is installed I true the crank assembly with a crank trueing jig that incorporates a dial indicator. Hope this is helpful.

marc

[firstturn]

Marc,
  It looks like you have done your homework.  I hope to install one of these soon on the next race bike that needs a rod kit.  Thanks for all the hard work.  I will try and keep you updated on any feedback.  Thanks.

Ron Carbaugh

[Lew Mayer]

Ron,
I've got one coming for a 5a motor. I'll let you know how it works.

Lew Mayer