cr125 front lower engine mount hole diameter?

[Michael Taksa]

Here is one for you technical guys....
What is the diameter on front lower engine mount hole on cr125?
I am using 3/8 there now, seems that the hole is a little bigger.... Are there any rubber inserts? 10mm bolt does not fit, 3/8 is loose and the bolt keeps braking. NOW THE BIG question.... If I drill out a hole to be exactly 10 mm would it create a problem in a way of going through cases to crankshaft chamber? As it is now it started chipping the aluminum little by little, because the bolt is less diameter then the hole.

[Bill Givens]

I just measured a case. It was 8.5 MM and Honda psrts manual says to use a 8 MM bolt. Sounds like yours has grown somewhat. Looks like you can go to 10 MM. Be careful...it's almost 5" across and will take an extra long drill bit. You'll have to drill it from the left side since there is not enough room on the clutch side for a drill chuck.

Check your motor mount and make sure it fits the case. Some mounts require some shimming to get a tight fit. If it's loose it will allow the motor to move a little and cause the problem you are having with breakage and eating up the cases..

[jessica]

Michael, the hole is actually tapered. Because you are using a 3/8" bolt I am going to assume you have '01 or '02 cases. From '99 and before a 5/16 bolt was pretty close. At PSR we use a softer bolt (closer to grade 5) because we have found it is better for the bolt to deform than to break. It is very important that the bolts both front and rear have a minimum of 'play', and that when tightened, they apply sufficient clamp load on the cases to eliminate movement of the cases on the bolt shank. Call us if we can be of further assistance.

J.R. Clasen, Power Source Racing
(760) 736-4007

[Michael Taksa]

Thanks for replies.
My question was mainly for engine builders to find out if there is enoguh "meat" in the cases to go to 10mm. It started out as 8.5mm and slowly grew in size to 9.3 now. I am also going to make the Engine mount holes larger and use some kind of dampers/spacers there to make sure the the bolt is realy snug in the motor but a the mount has some spring resistance to it. This is the way the rear is set-up. My theory is that not aloowing any movement in the front is the source of the problem, the motor is vibrating and therefore the mount hole gets bigger and bigger. I will limit any side to side movement, but I am thinking of drilling the motor mount holes to 12mm and using either hard rubber or bronze inserts there. let the inserts take the beating instead of the engine cases.