Stihl Piston

[sugarbush]

is the piston in a BR400/BR420 the same as an 028 Super piston?

 

[Dibbs]

is the piston in a BR400/BR420 the same as an 028 Super piston?

MS191T 46mm Piston is 1132 030 2001
MS270 46mm Piston is 1133 030 2001
BR400 46mm Piston is 4203 030 2001
034 46mm Piston is 1125 030 2002
028 Super 46mm Piston is 1118 030 2003
029 46mm Piston is 1127 030 2003
FS420 46mm Piston is 4116 030 2005

I can't see Stihl using so many different part numbers for the same piston, the first four numbers denote the unit (1118 = 028 Chainsaw), since the middle section is always 030 then you would assume (rightly or wrongly, I don't know) that means 46mm diameter, so, the question is about the last four numbers, I would assume the 2001s are the same, and assume the 2003s are also the same.

I just can't say for sure as regards to exact physical similarity, but as I stated the part numbers alone say they aren't the same.

 

[Freakingstang]

MS191T 46mm Piston is 1132 030 2001
MS270 46mm Piston is 1133 030 2001
BR400 46mm Piston is 4203 030 2001
034 46mm Piston is 1125 030 2002
028 Super 46mm Piston is 1118 030 2003
029 46mm Piston is 1127 030 2003
FS420 46mm Piston is 4116 030 2005

I can't see Stihl using so many different part numbers for the same piston, the first four numbers denote the unit (1118 = 028 Chainsaw), since the middle section is always 030 then you would assume (rightly or wrongly, I don't know) that means 46mm diameter, so, the question is about the last four numbers, I would assume the 2001s are the same, and assume the 2003s are also the same.

I just can't say for sure as regards to exact physical similarity, but as I stated the part numbers alone say they aren't the same.

First four digits are the model or series #, then the middle three numbers are the part designation on the saw, and the last four are actual part numbers

030 means piston/engine assy.

The fuel tank, carb, case, starter, clutch all have a set of numbers that designated where it goes on the saw and they are the same numbers for all models.

 

[Fish]

The ring on the 46 mm piston is part number 1118 034 3001, which also
fits a piston for the 029, 028, and 034, but the piston is different

 

[Lakeside53]

As Fish says...

If a Stihl part is the same on mnay models, it will have the same number no matter what model it's used in. In that case, the first 4 numbers would indicate the first model it was used on, not necessarily the model of current use.


Stihl really jacked up the price (like 40%) of the B400/420 piston recently. Luckily I have a stock at the old prices!

 

[BiodieselNC]

I am going to resurrect an old thread, because I am currently working on my personal Stihl BR420 backpack blower, and looking to do some mods while it is apart. It ran okay, but only blew 120psi compression, piston had some wear but jug cleaned up real nice. So now I am looking for a piston. I have not found an aftermarket piston, and can only imagine what a Stihl piston kit would cost. But I stumbled across the 028 Meteor piston, and with some modification I think it can work well. Here are the specs of the two.

Meteor 028 Super Piston
Bore 45.97mm
Height 38.5mm
Head Type: Crowned (3mm)
Piston Pin 10mm x 31.5mm x 6mm
Rings 46mm x 1.5mm
Compression/Pin Top to top of Piston 15mm
Compression/Pin Center to top of Piston 20mm

Stihl BR400/420 Piston
Bore 45.96mm
Height 36.25mm
Head Type: Flat
Piston Pin 10mm x 31.5mm x 6mm
Rings 46mm x 1.5mm
Compression/Pin Top to top of Piston 16mm
Compression/Pin Center to top of Piston 21mm

The latter of the two I measure with calipers, so they might be slightly off, for example the difference in bore might be from wear on my piston verses a new one. What sticks out to me is that the piston is longer, so I get more skirt length (and hopefully as much or more width) which will help cover the ports as I will have to drop the jug 1mm to get squish back to stock. Then, after milling the jug, I will take off whatever length I need from the intake port to get timing where I want. The longer skirts should adequately cover the exhaust port even with dropping the jug and removing the base gasket. Currently squish w/o the gasket is around .030"