Small Engines (Lawn Mowers, etc.): Stihl BR 400, stihl br, stihl equipment

Question
I am writing about replacing the cylinder head, piston and rings for a Stihl BR400 backpack blower.  The oem parts are close to $200. My current blower is 12-15 years old and used in a residential setting. I bought it used 10 years ago from a lawn care guy that was going out of business; it has worked flawlessly all this time. Last month it stopped working, I suspected sabotage from my sons.  I changed the gas, new plug, new filter, still did not work, I bought a new magneto, cleaned the carb, it started right up. Worked twice then stopped again.  I took the unit completely apart and noticed that the rings are fused flush (5-7mm) with the piston wall around the left border of the exhaust port. The cylinder wall does not appear damaged; the piston has vertical lines at the fusion point between the 2  rings.  I wonder if I just replace the rings will they move freely enough to keep the same thing from happening again soon.  Should I? 1) Replace the rings 2) replace the piston/rings 3) Try to find a after market cylinder head/ piston combo  4) Scrap the whole thing a buy a new blower?  Would you happen to have any of the after market parts that would fit the Stihl BR400?  The cylinder head says stihl U4203 on one side and Mahle 41ZD1 on the other. The height of the piston is aprox 36mm the diameter is aprox. 46mm

Thanks  Dana
Dankers7@AOL.com


Answer
Hello Dana:

I Like the Older Stihl Equipment and have Enjoyed Many Hours of Good Service Out of the Stihl Equipment I have. That Being Said, I Suggest you Purchase a New Blower. There are to Many Possible Problems with this Rebuild. The Cause of the Ring Problem is the Oil Ratio was a Little to Light. I Use a 32:1 or a 40:1 Ratio in All my Equipment. Even if the OEM Suggest a 50:1 Ratio, I Start at 32:1 and Correct the Ratio from there. I Usually End up with a 40:1 Ratio. Almost All my Equipment is Now Using the 40:1 Ratio. With the Newer Oils that are Used in the Fuel Mix a 40:1 Ratio Seems to Work Rather Well. If you Do Rebuild this Engine, then Make Sure the Piston Grooves are Clean and the Piston is Smooth. Remember to De-Glaze the Cylinder Wall and Replace the Piston to the Crankshaft the Same Direction it was Removed. There Should be an Arrow or Dot that Faces the Exhaust Port on the Top of the Piston. If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. Have a Happy Holiday Season and May the All Mighty Bless You and Yours. Be Safe and Happy. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Thanks.

Respectfully

John