# Question about new string trimmer



## Ryan'smilling (Jun 8, 2016)

After lots of research, I just purchased a Tanaka tcb-230sf trimmer. I'm very pleased with it so far, and I'm really glad i got one of the Japanese models instead of the new Chinese ones. 

Anyway, it has a non-adjustable carb, which is a bummer, but I'll get over it I guess. My question is, the manual calls for 50:1, but I run 40:1 in everything else I own. Will running 40:1 instead of 50:1 lean out the mix too much since I can't adjust the carb?

I asked the guys at the shop where I bought it and they insisted that increasing the oil will "richen" the mix. They did say that running more oil will make the engine run hotter (right, guys, because it's leaner). 

So, that's my question, can I safely run 40:1, or do I need to keep two mix ratios on hand? Also, how would I know if it's rich enough? Would I run it with no head to see if it 4-strokes at WOT?

THANKS!


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## catbuster (Jun 8, 2016)

No. 40:1 vs 50:1 will effect it negligably. Just go run it with what you have. Don't run it without a head, just go use it and stop worrying about it. It's not a rocket ship, submarine, racecar or ever a boom lift truck. I've worked on all of them, trust me. It's a string trimmer.


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## Section VIII (Jun 21, 2016)

The technicians are right 40:1 (40 parts gas to 1 part oil) IS richer than 50:1.


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## Ryan'smilling (Jun 21, 2016)

Section VIII said:


> The technicians are right 40:1 (40 parts gas to 1 part oil) IS richer than 50:1.



I don't think that's correct. Yes, 40:1 has more oil in it, but it makes it so that there's less gas in the ratio of gas to air that the engine burns. My understanding is that anything that you add to 2-stroke mix, whether it's seafoam or extra oil will make the engine run leaner. For example, a saw tuned for 50:1 will run leaner (at a higher RPM) on 25:1. 

This is info I learned on arboristsite. If I've been led astray, I hope someone can correct me.


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## GrassGuerilla (Jun 22, 2016)

Affirmative. 40:1 gives a richer oil to fuel ratio, but a leaner air to fuel ratio. As long as it's not puking oil out the muffler you should be fine with a simple 2-stroke. If it has a spark arrestor screen in the muffler I'd yank it.


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## Cycledude (Jul 13, 2016)

Why not just switch everything over to 50-1 oil ? that's what I've been running in all my 2 strokes for the last 40 years or so without any trouble.


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## fordf150 (Jul 13, 2016)

Tested this exact thing a few times in my shop....rpm change is so negligible between 40:1 and 50:1 that it's not worth mentioning or tuning for. Fill her up with your 40:1 and run it


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