Fuel Mix Ratios

Down_South · #1 01-15-2009, 04:49 PM

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...

MB-Monkey · #2 01-15-2009, 05:06 PM

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 · #3 01-24-2009, 12:29 AM

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.

svc · #4 01-24-2009, 04:09 AM

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 · #5 01-24-2009, 04:41 AM

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 · #6 01-24-2009, 06:00 AM

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.

Pablo · #7 01-24-2009, 07:55 AM

Plugs are so cheap. I don't get it.

Down_South · #8 01-24-2009, 12:57 PM

"...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.

Bikeguy Joe · #9 01-24-2009, 01:58 PM

#4 is hotter than the 6 or 7... I would try a new 6 and the clip at the second from the top, with a 24:1 mix.

Down_South · #10 01-24-2009, 03:19 PM

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.

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!!!