Older 044 and large pin piston

[KMB]

I recently got another case/crank/bearings assembly (serial #1 30 XXX XXX = 12mm pin piston) for my 044 project. I took the piston off of my original case/crank/bearings assembly for curiosity (will be getting a new Stihl piston/rings for the new-to-me case assembly) and found that it fit on the other crank (of course with the needle cage bearing in place). The reason I was/am surprised is because my original case serial # is 1 25 XXX XXX, and after serial # 1 29 XXX XXX is supposed to be when the piston pin went from 10mm to 12mm. So my original piston should have been a 10mm pin. I measured the pin's diameter with my dial caliper and it said 0.4725 inches - which is 12mm. Also I thought that the 12mm pin crank would not fit in a older serial # case. Maybe it actually does. I don't know. Anybody have a better explanation? Not really a big deal, just curious.

Kevin

 

[Lakeside53]

What's the part numbers cast into your crankcase halves?

 

[KMB]

What's the part numbers cast into your crankcase halves?

On both crankcases the part numbers are the same - 1128 021 0702. In my IPL it says that the part number is 1128 020 2103 up until serial number X 25 454 553, and after that the number is 1128 020 2122.

Kevin

 

[thompson1600]

My understanding on the 044 was they changed the wrist pin size, and the crank radius size. The new cranks are larger than the old ones in spinning radius and aren't supposed to work in the older style cases, however they can, but will rub. I've run across a couple saws where people put that crankshaft in an old case. It really tears the inside bottom of the case up, but after it wears it away, it will work. Leaves lots of scraps inside the case to scratch stuff up too.

 

[Lakeside53]

The crank did change.

Enclosed is a tech note... It doesn't say it won't fit, just that you shouldn't do it...

 

[KMB]

I've run across a couple saws where people put that crankshaft in an old case. It really tears the inside bottom of the case up, but after it wears it away, it will work. Leaves lots of scraps inside the case to scratch stuff up too.

Thanks for that. Could be what happen in my situation. There is some stuff in the bottom of my original case. But the part numbers on the cases are the same for each - with serial numbers for different crank changes.

Kevin

 

[KMB]

The crank did change.

Enclosed is a tech note... It doesn't say it won't fit, just that you shouldn't do it...

Once again Andy, you da man! Thanks for that info. I measured the small end of both cranks (0.59") which proves to be the updated versions. Some part numbers are different between the IPL and the tech note.

Kevin

 

[Lakeside53]

The tech note show the latest part when written (95?); the IPL shows the latest parts in use when it was published (several times a year now). There can be several others between the IPL and the technote. I have a phone book sized cross reference for those... most of them...

 

[KMB]

The tech note show the latest part when written (95?); the IPL shows the latest parts in use when it was published (severl times a year now). There can be several others between he IPL and the technote. I have a phone book sized cross reference for those... most of them...

aaaahhhh, I understand. I learn something new everyday...most everyday . As always...thanks Andy.

Kevin