MESSAGE BOARD

tom42m · Joined: 12 Mar 2010 Posts: 82

Just fininshed my `75 125 Elsinore. Rebuilt motor, FMF cyl, DG sand cast head and pipe, 34mm carb, thor swingarm. Two runs down the driveway, really fast. Two revs before I shut it down and the rod decides to exit thru the bottom of the crank case and is now in plain site sittng on the driveway. Well At least half of it is. I`m sure I can find some cases, but what about the rod. What do I replace the rod with? Thanks, Tom

rspkwalt99 · Joined: 31 Dec 2008 Posts: 21

Tom,

Man hate to hear that. I thought that only happened to me and on new 4 strokes. I'll keep my ears open for parts. Any luck with Sam and your motor stuff?

Take care.

Bob

mkcwiggy · Joined: 14 Jun 2009 Posts: 16

- - Wow-- -Did you ever hear about proper motor break in procedures? Really Fast? Who did your motor work? - - WFO- - - Wig-Kat

Doug Childress · Joined: 28 Dec 2004 Posts: 359

I'd have Bill Clem put it back together with one of the big rod kits he uses. Have some buddies who have gone that route and no more problems.

tom42m · Joined: 12 Mar 2010 Posts: 82

The rod clearance was good so I didn't replace it. It broke both sides of the cylinder skirts off too!!! Guess that will be going to NW Sleeve. Hey Bob hope all is well. No I haven't heard a thing. Last I heard was his brother was maybe going to help.

Tom

cr125ted · Joined: 19 Mar 2009 Posts: 40

have to ask you

" It broke both sides of the cylinder skirts off too "

were you running a 74-75 cylinder on a 76-78 bottom end ?

74-75 cylinder have a smaller cylinder sleeve base o.d. than 76-78

and 76-78 lower case's have a larger i.d crank hole than 74-75

(He said crank hole Bevis)

ted1 · Joined: 04 Jun 2010 Posts: 3

I have a 1975 lower end I would be willing to sell. I don't know the condition, but the cases are in great shape! I used to race the 76-77 CR's when I was younger and have recently been collecting all of the old parts I can find to build a complete 76 for a personal collectable. I have NOS crank shafts for the 76-78, NOS center cases for the same, and complete NOS transmissions. I also have many other parts, including frames and swing arms, wheels and other NOS and used pieces.

melmark · Joined: 04 Apr 2009 Posts: 27

A big rod kit is probably the way to go but if you want to use an oem rod you can always pick up MT125 cranks on the auction site. They have 3 or 4 listed now. I picked one up for a rebuild of my 75 CR and it was just like new from a very low hr MT. I got the whole crank for 35 bucks plus shipping. The crank is different but the rods are the same.

davidgoat · Joined: 31 Dec 2008 Posts: 207

tricampbell · Joined: 31 Dec 2008 Posts: 12

Have new rebuilt engine with large rod kit - $1500.00

Reed Inducted Engine
DG Milled Head
Ported and Polished
etc......

Ready to Blast.....

melmark · Joined: 04 Apr 2009 Posts: 27

tom42m · Joined: 12 Mar 2010 Posts: 82

Thanks for all the help. Ted1 can you email me please for parts ?

tom42m@hotmail.com

Thanks, Tom

jrobertsonracing · Joined: 27 Jul 2011 Posts: 2

Hi Tom, The big rod kit uses the 1980 cr125 rod. They install them with either a stepped crank pin or machine the crank halves to fit the larger pin diameter, dosnt seem to matter which method they both hold up. Bill Clem did all of ours I think your buddy JP puts them in also. I have cases also if it dosnt work out with the other guy. When the rod goes they almost always break both cases and the bottom of the sleeve off, weve broke em all, on both 74/75 and 76/77 cases. No failures after putting in the big rod.

Jeff Robertson

tom42m · Joined: 12 Mar 2010 Posts: 82

Thanks Jeff. Can you email me about cases? tom42m@hotmail.com

cr125ted · Joined: 19 Mar 2009 Posts: 40

and yes the MT 125 crankshafts will work just fine in a CR 125, if you check the online parts fiches you will see that Honda superseded the CR part numbers with MT part numbers