Stihl BR500-BR700 Rebuild Center
The Stihl BR500, BR550, BR600 and BR700 backpack blowers all share one 64.8cc 4-MIX engine. This page covers the part numbers our parts replace and the checks that get you the right part for this engine.
At a glance
| Blowers | Stihl BR500 · BR550 · BR600 · BR700 |
|---|---|
| Engine | 4-MIX, 50mm bore, 64.8cc. Same engine in all four. They differ in fan housing, blower tube and air output. |
| Piston | Replaces 4282-030-2003 (superseded to 4282-030-2005) |
| Rings | 50mm standard bore, replaces 4282-034-3000 |
| Valves | Intake: 4282-025-1801 Exhaust: 4282-025-1903 |
| Valve clearance | 0.10mm (0.004 in), intake and exhaust, checked cold |
| Crankshaft bearings | 9523-003-4301 (two per engine) |
| Crankshaft seals | 9638-003-1581 and 9639-003-1585 (flywheel side and clutch side are different parts) |
| Not these blowers | BR800 family (piston 4283-030-2003) · BR350, BR430, BR450, SR450 (48mm two-stroke, piston 4244-030-2006) · BR340, BR380, BR420 (two-stroke) |
Check these four things before you order
- The model on the frame plate. The BR800 piston number is 4283-030-2003. It differs from this family's 4282-030-2003 in the fourth digit and does not fit. Check that digit on your parts list. Where to find the tag
- 4-MIX or two-stroke. The BR350, BR430 and BR450 are 63.3cc, close enough to look like a rounding difference. They are 48mm two-strokes with no valves. If your engine has no valve train, it is not this family.
- Which seal you need. The two crankshaft seals are different part numbers and are not interchangeable. Match the number on your parts diagram, or get the set with both.
- Why it failed. These engines have no oil sump. Everything, valves included, is oiled by the fuel mix at 50:1. Straight gas wrecks the valve train and the piston. A hardened seal, cracked intake boot or blocked fuel filter will score a new piston too.
Which kit do I need?
- Scored piston, gaskets and seals are good: the 50mm piston kit (piston, ring, wrist pin and circlips). Line up the painted timing marks on the cam gear when it goes back together.
- Rings only: the 50mm standard bore ring set.
- Low compression from a burnt or worn valve: the intake and exhaust valve set, or a single intake or exhaust valve. Set clearance to 0.10mm cold on both.
- Bogging, running lean or won't hold an idle: the crankshaft bearing and seal set (both bearings, both seals), or the seal pair. If the case is split, do all four pieces and pressure test before it goes back together.
More on measuring before you order: Measure before ordering rings and pistons.