Fuel Mix Ratios

Down_South

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Aug 28, 2008
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Hey, I'm wondering what the fuel ratio range is for these engines. As far as I know, people "break in" the engine with 16:1, then they start using a tank of 20:1 followed by 32:1 in some cases. The engine still smokes considerably with 32:1.

How much smoke is nominal?

Too much oil is just as bad as too little?

What is the best way to measure the temperature of the cylinder and how hot does it get?

600°C - 700°C (1,112°F - 1292°F) is the range where the spark plug reaches self cleaning temperature or that's what I read on NGK's web site.

Let me know what you think...
 
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MB-Monkey

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Nov 19, 2008
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i ran 20:1 for the first 2 tanks
then moved to 32:1
I would run conventional oil during breakin
switch to synthetic after

Smoke is common with 2 strokes some oil mixes are better than others and synthetic normally burns very clean.

Too much oil is just as bad as not enough oil for sure.

engine paint starts at 650* so i would imagine a freshly used engine would rise above the "self cleaning" temps of the plug although i would never trust it to clean itself a little sand paper goes a long way

My two cents anyway
 

Down_South

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Well, I fooled around with the carburetor throttle linkage tonight. I adjusted the E clip to the highest position on the shaft that goes in the primary jet/nozzle. I noticed a profound difference in engine performance and noticed lower emissions. I've been using some fouled up plugs and it looks like the engine temperature is getting high enough now to clean off some of the carbon fouling.:D:D:D
 

svc

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Jan 10, 2009
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smoke is good. If you have no smoke you are completely burning you're fuel AND oil. Its not like a 4 stroke where smoke is a bad sign.
 

svc

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Jan 10, 2009
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to add to my last post. If youre plugs are fouling on a mix of good 2 stroke oil after your motor has run in, I would suggest raising the clip on the needle at the end of your throttle cable 1 setting. After run in use a good quality oil. black plug raise the clip (lower the needle/ lean out) grey or white plug lower the clip (lift the needle/ richen the mix). You are looking for a nice chocolate colour.

While you are running in your engine it is hard to tell from just a spark plug. So do some km's and then get a high grade oil before you touch anything.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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CODE BLUE!!!!! aluminum melts at a little over 1200F, so don't even try to "self clean the plugs".

Using fouled plugs will cause all kinds of problems, and new ones aren't very expensive.

If you HAVE to clean a bad plug, use a torch, not by torching your engine.
 

Down_South

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"...You are looking for a nice chocolate colour..." OK. I have a carb needle with 5 positions and the default setting was in the middle (3rd one down). I'll have to put it on the second one from the top and see how well it does. The important thing is that I learned how to control the jet. Have any of you had a spark plug that looks "wet and oily"? Running the needle on lean has naturally kept the spark plug dry with no carbon build up.

I have an NGK 4, 6, and 7 as my heat ranges. The #4 plug was being fouled with the default needle setting and began running clean (white ceramic) on the lean setting. I'd like to stay with #6 plugs.
 

Down_South

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10-4 Joe!!! I'll do that. I went out earlier today and adjusted the clip to the second position. That's when my old woman started hollering at me to cut down a big old honking holly bush in the yard. I had fun, I was covered in red berries and thorny leafs for about an hour but I got my revenge with my two cycle chain saw and an old mulching machine.:D I've got to go out later and refill my 2 gallon gas can. What's the best oil? I'm using Wal-Mart SuperTECH Universal TCW-3 (I can buy that stuff by the gallon for about 10 bucks) How do y'all feel about fuel additives like STABIL? I've wondered about it and the only thing I can think of is that it might "protect" the fuel from gumming or leaving varnish/residue in the carb. It says it'll work in 2 and 4 cycle engines, so I figure I'll give it a shot. Tell me what other (if any) additives you've used and how well they worked. I'm working on a software program that tells you (based on input) how to mix a desired ratio and what cost will be. I've got lots of the program complete but I need to put in a few logic controls so it won't try to calculate unreal data values and then crash. I've got some physics projects that I have to finish up for school and I probably should get to it. THANKS TO ALL for the AWESOME advice, I'll keep you up to date and look forward to hearing (or reading) from y'all!!!
 

svc

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Jan 10, 2009
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the oil im using at the moment is silkolene 2T 'kart racing'. synthetic with castor oil blend. All i really look for is the cheapest synthetic i can find.
 

Down_South

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Ya, I like pinching pennies too ( good 'ol Lincoln has a clean nose for sure [no boogers] LOL :D ) I took a break from physics homework and ran my bike around the block a couple of times before the sun went down. Runs good, the plug (#7 IridiumIX ) was a little wet {but it wasn't an intolerable amount}. Emissions were low and temperature was decent. I've used the synthetic stuff that comes with a Weedeater and it's ok. I haven't done my homework on differences in price between synthetic and conventional. I'd also have to weigh the cost benefit (can you tell I'm a little Jewish?). Synthetic supposedly burns cleaner and protects better, but is there any scientific way to prove it (I've seen lots of "Snake Oil" products on the market)? I've used synthetic motor oils before, but if it works for years just fine on conventional what am I really buying? Cheap insurance? I guess, but is it really worth it? Some companies have fooled around with marketing, calling a 50/50 mix of conventional and synthetic simply "synthetic" motor oil and other times marketing "100% Synthetic" motor oil. Not trying to criticize anybody I just need to do some homework. What has your experience been with synthetic? Is it really justified? What about MPG? Speaking of which {sorry for getting a little off topic} Tires --- Is it a good idea to run with tires a few (-2 to -5) PSI lower to prevent skidding in an emergency stop?
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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up north now
Super Tech 2 cycle oil- I haven't used it, I honestly didn't know ST made a two cycle oil. I DO use Super Tech in ALL my other vehicles, including my motorcycle.

But...as long as it is for air cooled engines (weed wacker, chain saw, ect), and NOT FOR OUTBOARDS you'll be fine.

I use the Penzoil for air cooled engines. (non synth.)

Now, about Stabil- awesome stuff but in a two cycle ONLY USE IT WHEN YOU NEED IT, not all the time (waste of money unless you plan on letting the fuel sit for awhile) Don't use too much, it makes your 2 cycle engine run like crap. Use slightly less than the recommended "doseage".
 

Down_South

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Aug 28, 2008
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I've used the outboard stuff, but only because it states clearly on the back label that it can be used for motorcycles, mowers, etc. But I guess you're right TCW is designed for water cooled engines (hence the "W") but I've been using it on air cooled engines for years with no trouble.
 
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toytime

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Mar 20, 2008
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A bottle of the best synthetic is under ten bucks and lasts for months and it is the most important thing in a two stroke.
 

Down_South

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Aug 28, 2008
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That oil from Polan/Weedeater is impressive because it's designed to not smoke. I guess there are certain folks who like smoke and those who don't. I heard one fella call his 2 stroke engine a "two smoke" engine LOL rotfl I'll try some of that synthetic stuff some time, but in in the meantime I'll have to use up that universal stuff from Walmart. I just wish Walmart would have a larger selection of 2 cycle oil. I live out in the sticks and the nearest Walmart is at least 10 miles away. Do any of you know who sells universal 2 cycle oil by the gallon (55 gallon barrel would be Oil for life - Anyone got a barrel tap? LOL). wally's only has the gallon size of outboard oil and it works OK, but I'd rather not risk it for too much longer. Anyone use that Itasca stuff at the BP gas stations?