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Discussion Starter · #1 ·
Just wondering if there's any precedent for adding just a little two-stroke oil to the gas in a CB350 -- particularly one that's ridden hard -- to help add a little lubricity to the fuel, which modern gas (especially with ethanol) lacks, and to help keep the top end happy? It's something I've done with other small, non-catalyzed four-stroke motors with no apparent ill effect.

Did a search of the forums, but didn't find anything.

Cheers.
 

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Won't hurt a thing, good upper cylinder/valve guide lube. Two cycle oil has detergents in it, so it doesn't leave ash deposits behind, like outboard motor oil. Also works as a gas stabilizer, in the off-season. ATF works good too, plus it tends keep the carbs a little cleaner.
 

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I use TC-W3 2 stroke in all my vehicles, with and without catalytic converters. Cleans up fuel injectors over time and doesn't stink like the usual fuel stabilizers ... especially noticeable when we owned a BMW Z4 roadster. Converters can handle the small amount of product used.
 

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The CL125 I'm working on hadn't been cranked up in like 10-12 years. The first gallon I put into the tank was 2 stroke for just that reason you're talking about: lubricating the top end. (I just used the chainsaw/trimmer gas that I already had mixed up in the garage). Worst thing that happens is it'll smoke a bit more out of the tailpipe.

Not that it matters, but I use Stihl HP Ultra 2 stroke oil with some Sta-Bil. You can choose whatever you want.
 

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I add MMO (Marvel Mystery Oil) to the gas regularly for that purpose and it apparently keeps the carbs clean(er).
 

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Just wondering if there's any precedent for adding just a little two-stroke oil to the gas in a CB350 -- particularly one that's ridden hard -- to help add a little lubricity to the fuel, which modern gas (especially with ethanol) lacks, and to help keep the top end happy? It's something I've done with other small, non-catalyzed four-stroke motors with no apparent ill effect.

Did a search of the forums, but didn't find anything.

Cheers.
How much oil do you add per litre of petrol?
 

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50:1 is what would be used for a 2-stroke, not a 4-stroke! I do not believe adding oil to the gas for a 4-stroke is a good long-term procedure. You would be better off using proper fuel additives like Techron.
 

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50:1 is what would be used for a 2-stroke, not a 4-stroke!
I know. That's the entire point. On an engine that hasn't been run in a long time, 2 stroke oil is good for it. The 2 stroke gas keeps the top end lubricated.

Once you put a tankfull of 2 stroke through the motor, you can then switch back to straight ETHANOL-FREE gas.

There is no way in Earth I would ever put ethanol into a small engine. It wreaks havoc on the carbs.
 

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What kind of havoc does gasoline with ethanol wreak? I have been using standard pump gas for as long as it has been available in motorcycles and other small engines with no observable damage to the carburetors. This is probably true of 98% of motorcycle and other small engine users. In many parts of the country, particularly away from where boating is popular e-free fuel is not available or costs $20 /gal in small containers. I have found that it is useful to run the carb dry if the machine is not going to be restarted for a week or more. This seems to improve starting and avoids having to drain the float bowl manually.

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There is no way in Earth I would ever put ethanol into a small engine. It wreaks havoc on the carbs.
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I have a side gig of fixing mowers and other small engines. When I get a tool in and pull the carb, I can instantly tell when the owner used ethanol instead of pure gasoline. The ethanol gums up the carbs, big time.

If you burn through a lot of gas, well, ethanol is okay, because it never in the tank and carb long enough to do any damage. It's flushed out constantly. But for weekend warriors, and especially in something like a mower or motorcycle that doesn't get used much if at all over the winter? OOF.

Just not worth it.

And, as an aside, gasoline mixed with ethanol doesn't make as much power as straight gasoline, nor do you get as good gas mileage with ethanol. It's true! A given volume of ethanol has less potential BTU output than a given volume of gasoline. This makes for worse gas mileage and less power.
 

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So the real issue is that E-10 only bothers carburetors because they have float bowls and people fail to empty the bowls if the machine is not going to be used within a few weeks.
It is true that ethanol mixed with gas will produce lower power (and less heat) if the engine compression ratio and timing advance are unchanged. By most measurements E-10 results in less than 3% power loss and mileage decrease. So called flex-fuel vehicles running E-85 can have a more than 10% decrease in gas mileage. Take a look at Indy cars to see what engines designed to run pure ethanol can do.
As far as carburetor gumming goes, I have been working with carburetors since before unleaded was required and way before ethanol. I have seen real gumming or varnishing in carbs that had been inactive for only a few months that was much worse and harder to clean than post ethanol carbs that had been inactive for several years.
Realize I am not a fan of ethanol mixtures. I believe it is another government construct to help a small group and penalize the majority. The current implementation is likely doing more harm than good. If we were serious about ethanol as a fuel we would make it from sugar cane and not corn and other relatively low sugar plants and we would design and build engines to maximize its benefits.
 
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