Fuel Mixture

[Mike Korgan]

I've have a 1977 MC5 250. I'm using Spectro and mixing at 32:1. I've got a lot of oil coming out of the pipe. Is anyone going leaner on your mix?

[Bob Bean]

Your jetting is too rich
Bob

1986 ISDE Italy
1987 ISDE Poland
1989 ISDE Germany

[wfopete]

I think Bob's right; it's jetting. Today's oils burn pretty clean but I haven't done 32:1 since the early 80's.  Shoot I'm currently running 40:1 (Maxima 927) and that is considered rich by today's standards.  I'm about to move into the 50:1 arena.


Pete Petrick
175 Jackpiner
Slow but Good

[Mickey Sergeant]

I have used yama lube at 32:1 for years.I race my Berkie and Six Days hard.If you want these old engines to last you need to be on the rich side.If you have oil coming out of pipe I would say your to rich on your jetting.You want to see some smoke.PLug should be a chocolate brown.

[rob w]

Spectro 40:1 for me

[OUCWBOY]

Just to show how the mixtures have changed, we used to run 20:1 back in the 60's..

Donny Smith
Paragould, AR

[johnborn]

I have always used golden spectro concentrate mixed at one 12oz bottle to five gallons of gasoline with no problems whatsoever.which is 53.3 to one. I have used this oil since hi- point went away in every bike i've had.I also used the same ratio with the hi-point oil  (sine 1972) I also use the old gas out of my bike in my powered lawn equipment.In my opinion if you are using the spectro concentrate at 32:1 it is way too rich,however if you are using the spectro s/x i believe it calls for a richer mixture.

[Kip Kern]

I'm with John B.

[Mike Korgan]

Thanks everyone, I'm currently running 1 bottle to 4 gallons, I  was thinking the bottle was 16oz. So it's actually 42:1. Sounds like I can go a little leaner in the mix.  I still have 20:1 stuck in my mind. Thanks again.

[Bob Bean]

If you go leaner on the oil mix, your bike will get richer..
Bob

1986 ISDE Italy
1987 ISDE Poland
1989 ISDE Germany

[wfopete]

quote:Originally posted by Bob Bean

If you go leaner on the oil mix, your bike will get richer..
Bob

1986 ISDE Italy
1987 ISDE Poland
1989 ISDE Germany

and with the cost of 2T oil, if you go leaner you'll be richer too!

Pete Petrick
175 Jackpiner
Slow but Good

[Ron]

The oil burns when the combustion chamber temperature is high enough to reach the oil's flash point. Reducing the oil to fuel ratio is not a fix.
Gasoline is what cools the engine and oil provides lubrication.
If you have excessive oil coming out of the pipe your combustion chamber temperature is not high enough.
I've seen dyno test where an engine made its best power at 16:1. The down side is excessive carbon build up. But lubrication makes a difference.
When your jetting is to rich the excess fuel is cooling the combustion chamber temperature below the flash point of the oil and raw fuel and oil is going right out into the pipe.
Most people understand jetting, so you don't seize at wide open throttle, but don't consider that most of us don't stay wide open for very long.
Quite often its the low and mid speed range (closed to three quarters throttle) where we ride most of the time and jetting in those ranges is just as important as high speed jetting.
Just having a pilot jet that is to large can cause excess oil coming out the pipe over time.
Checking the plug color at 1/4, 1/2, 3/4 and wide open, will control excess oil with any oil or ratio you choose.

[brian kirby]

Ron is exactly right, excess oil at the exhaust really has nothing to do with the oil type or ratio, its completely a result of too rich jetting, almost always too rich on the needle/needle jet.

Here is a picture of my modern Honda CR500 running 32:1 Maxima 927 castor.



Absolutely zero smoke at any throttle setting other than idle, and its because its jetted perfectly. If you look right at the tip, you can even see the heat mirage, but no smoke.

Brian

[Speedy]

quote:Originally posted by wfopete

I think Bob's right; it's jetting. Today's oils burn pretty clean but I haven't done 32:1 since the early 80's.  Shoot I'm currently running 40:1 (Maxima 927) and that is considered rich by today's standards.  I'm about to move into the 50:1 arena.


Pete Petrick
175 Jackpiner
Slow but Good

I have used OPTI in 1962 at the ISDT with a mix of 50-1
In 1970 OPTI came to Canada and since then I ( we ) use it mixed 100-1. Yes times have changed.Oil and materials are so much better.
I use SHELL Super,the only company in Canada who does not have methanol in his high test gas.

In any case,proper carb adjustmend is a must.( easy with a Lectron) Lolol

[wfopete]

Speedy

Have you seen these?:

http://www.powerapt.com/smartcarb.php

It's like a Lectron on steroids.

Pete Petrick
175 Jackpiner
Slow but Good