4 mix advice

[billy110]

Hi all.

 

I have just bought a BR500 backpack blower off eBay and am looking for a bit of advice. The previous owner ran it on a 25:1 mix for some reason. Is there anything I can run through it to give it a blow out without damaging it or should I just run it on a 50:1 and leave it? I should add it has only had very light use and runs perfectly, just seeing if some preventative maintenance was in order!

[GardenKit]

Just run it on a good quality, low ash oil at 50:1. It may smoke for a while but will eventually clear up and dry up. Only if you have running trouble in the form of not reaching full revs will you need to think about de-coking the exhaust.

[pleasant]

If the oil you are using states a dilution ratio of 50:1 then 50:1 it is. Most, good oils from Stihl Husqnarna etc are 50:1 rated. Cheap, generic mineral rubbish oil from Halfords, b& q etc won't have a ratio stated on the bottle and that's where people go wrong. No need for a "blow though" (whatever that may be) just drain off and re-fill with known quality oil and fresh unleaded.

[billy110]

Thanks guys, I'll drain off what little fuel remains and put the correct through it. Regarding a blow out, I thought there may have been a treatment I could put through it to clean the carb after excessive oil has been put through. But as you say, I won't worry unless I notice a drop in performance. Thanks!

[pleasant]

Never use a proprietory treatment- not recommended.

[Gareth Dalzell]

Stihl hp ultra is the one we were recommended to use after screwing up 3 br550 blowers one after the other. This was the advise given to us by our local stihl dealer as recommended at their last stihl dealer update. haven,t had one go since. Although I wouldn't,t buy another 4 mix engine again. The 2mix ones seem to be going fine - so far and we,re running them on normal two stroke

[TimberCutterDartmoor]

Yes indeed, synth 2 cycle oil is recommended in this case; many a 4-mix engine has had valve probs due to lubrication issues... or so the dealer tells me...