STIHL BR600 Decoke problem

[ricky86]

Originally Posted by piston slapper

I was hoping someone had come up with a caustic solution that would eat carbon and wouldn't harm steel or aluminum.
Guess I should just add it to my christmas list.
Thanx again Fish.
Posted via Mobile Device

The Stihl decarbonizer works wonders. The engine really has to be hot for best results. Depending on the amount of build-up, you can let it sit in the cylinder for 24-36 hrs cold. It won't hurt anything. Heat helps alot.

[DR J]

May try mechanic in a bottle, we use to decarbon pistons and valves on motor remans and 2 cycle remans very good prod. aslo use it in ultrasonic cleaner with heat to do carb rebuilds.

[DR J]

mechanic in a bottle. also use in ultrasonic cleaner with heat to decarbon pistons and valves on various units, works great also on carb cleaning before rebuild wonderful prod.

[piston slapper]

All of the 4 mix units in the bonepile have been run on the cheapest mix oil and the cheapest fuel.
The valves were never adjusted. For the most part, the local dealer told them they were blown up regardless of their condition.
In turn the dealer sold them about 50 units a year.
I may try some stihl decarbonizer, as the only way to heat them up is with a torch.
Posted via Mobile Device

[caranheim]

I would think lapping the valves in the 4Mix engine would be very difficut bcause even though it is an overhead valve engine, there is no removable head. You would have to remove and completely disassemble the engine to get to the valve heads by working through the cylinder.

[piston slapper]

Its not a 5 minute job.
Its just a little easier than repairing a ship in the bottle.
Posted via Mobile Device

[ed2hess]

Originally Posted by caranheim

I would think lapping the valves in the 4Mix engine would be very difficut bcause even though it is an overhead valve engine, there is no removable head. You would have to remove and completely disassemble the engine to get to the valve heads by working through the cylinder.

That is exactly why us guys who want units to run a very long time stick with 2 stroke. And you don't have to be a master mechanic to do the repairs.

[ed2hess]

Oh and besides not having valves they don't have a lot of other stuff the 4 mix has.

[caranheim]

When I called STIHL support to ask about decoking the BR600 4 Mix engines, I was told it would not be necessary if you use the STIHL Ultra synthetic oil correctly mixed with fresh 89 Octane gas. I mentioned that the Owners Manual for the new BR600 Magnum still recommends decoking the engine at 139 hours, and every 150 hours after that. He said the manual updates have not kept up with the current recommendations. I did not ask about checking valve clearances. I would think it still should be done every 150 hours. I found the clearance changed the most (Got larger) the first time I checked it. I checked it once each year, two times after that. The third check only showed a very small change in the exhaust clearance. Again, it was a little wider than it should be, using the STIHL feeler gauge. My STIHL dealer now only sells the Ultra oil. I may be wrong, but I suspect few landscapers take the time to decoke their SHIHL blowers. Here in Connecticut, the BR600 seems to be used more often than the other brands.