How To MCculloch MC100 parts help

[brandonstc6 temporary one month membership. member needs to add real name to membership to become full member. contact administrator for help]

Does anyone happen to know the part numbers for Standard seals to replace the 3 used on a mc100 kart motor? Also are there standard rollers to replace the needles on the connecting rod. I am hoping I can get the parts from an industrial bearing and seal supplier.

[Richard Stamile]

Does anyone happen to know the part numbers for Standard seals to replace the 3 used on a mc100 kart motor? Also are there standard rollers to replace the needles on the connecting rod. I am hoping I can get the parts from an industrial bearing and seal supplier.

you better hold on to the needle bearings that you have don't loose any and count how many there are
from what i hear on this site that is a big problem with vintage MCculloch engines and using them

[Scott Kneisel]

Yes, the needle rollers are a custom size that McCulloch had made and used in most of there engines.
I contacted a needle bearing supplier a few years ago and they required a minimum order of 60000parts  to tool for them so I dropped it. They are getting difficult to find but you can re-use them if they are not worn too much. I measure each needle and if the diameter is worn less that 0.0004" I re-use them as long as the rod and crank journal are not worn much either. It is the total clearance between the needles, rod and crank that is important.

The seals are still made and are off the shelf items.

PTO seal for an Mc100 is SKF 7829 or 7821

Flywheel side inner seal is a 17x30x5 mm seal and can be found with many suppliers, SKF6763 for the inner seal
The outer flywheel side seal is 17x30x3mm, SKF 6762  that may be tough to find, I have NOS of that type if you need a couple.

Good luck,
Scott

[steveohara]

OEM McCulloch Needle bearings $25
OEM Mc 100 seal kit (3 parts)  $15
Shipping $7.20 USPS Priority Mail
Payment via PayPal or check
Steve O'Hara
steveohara@msn.com

[Dean Richards]

Hey Scott, Just curious what the diameter of the needle bearings should be on mc100,and mc 101's. I have a 101 that I need to go through. Thanks, Dean Richards.

[Scott Kneisel]

Hey Scott, Just curious what the diameter of the needle bearings should be on mc100,and mc 101's. I have a 101 that I need to go through. Thanks, Dean Richards.

Dean,
The nominal diameter of the needle is 0.0944"
I have never measured a new one that varied more than 0.0001" off of that number.

I use them down to 0.0942"  and even 0.0940" depending on the crank and rod diameters.

Have not had an issue so far.  

[Al Hasenfratz]

So how do you arrive at the final, measured running clearance?

[David Luciani]

take stock measurement for crank diameter , connecting rod i.d. in bore and bearing size.
add crank dia and total bearing dia together.
the difference between those two and the i.d. number of big end of rod is the acceptable amount of clearance in set up.
in most parts you will find them a little undersize on the crank surface and bearing surface.
the rod will be slightly oversize .
to much wear in all the parts will make for a loose engine.
may be fast but won't last long.

brian santee is working on different project.
he may have figured out slightly bigger bearing source.
maybe he'l post his findings if he reads the thread,

[Scott Kneisel]

Al,
Rod ID - (Crankpin OD + 2x needle bearing OD) - This gives total clearance which works out to 0.0032" for new nominal size parts.

I think that can grow to about 0.005" without problems.

Like Dave said, if it gets too loose it will be fast but engine life will suffer but I do like to run them loose.

Good luck,
Scott

[Al Hasenfratz]

Thanks, guys....