Oil fuel mixture (more is not better)

tyrslider · #1 10-02-2008, 09:58 PM

I see a lot of threads of people using too much oil. This is not adviseable. If you use too much oil w/ out using a larger jet you are actually running leaner. Only so much mixture can go through the hole in your jet, so if you have a higher ratio, i.e. more oil in your gas, then less gas is going through (lean condition is the enemy of 2 strokes). So even though you have more oil you can still sieze your motor and even if you don't sieze, your motor will run hotter, you will probably lose power and you'll have to service your motor more often. The appropriate octane gas, burning properly will also regulate engine temp. I'll leave it open to others w/ more "bicycle motor" experience what gas is better, But I would think w/ only 6:1 compression 87 octane (regular) is best. But just as an example I built a Yamaha rd 350 w/ 70 hp, 10:1 compression (stock is 37hp) and ran 110 octane leaded gas at 33:1 mixture. More is not necessarilly better!

CalgarysFool · #2 10-03-2008, 02:40 PM

An RD 350 with double the original HP? I'd love to see that -- Not ride it myself, but see it. That is one of my most favorite bikes of all time!

I'm a tad worried about oil mixture now. Spookytooth advises 20:1 at break in and ever after! I've read many alternate suggestions here, but this is the first time I've read that my 20:1 plan may be a bad idea.

I'd really like to hear more about this, so I can be better informed as I get beyond my break in period.

Thanks in advance, guys and gals, for any contributions here.

Brenton

OSCAR383 · #3 10-03-2008, 02:57 PM

i ran 20:1 my first 2 gallons , 4 tanks, and now i run 32:1 on good ol 87 octane

MrLarkins · #4 10-03-2008, 03:15 PM

i put 4oz oil to 1 gallon gas.

FileStyle · #5 10-03-2008, 05:31 PM

4 oz. to the gal.

misteright1_99 · #6 10-03-2008, 06:13 PM

Yep 32:1 quality oil........

old motorbike · #7 10-03-2008, 11:31 PM

I'm using 16:1 oil the first week and it still 4 cycles some of the time, mostly at higher revs. (isn't that too rich?)

misteright1_99 · #8 10-03-2008, 11:59 PM

Quote:

Originally Posted by old motorbike

I'm using 16:1 oil the first week and it still 4 cycles some of the time, mostly at higher revs. (isn't that too rich?)

No that is what the instructions recommended for my engines also. It helps get everything seated and broken in..

tyrslider · #9 10-04-2008, 01:37 AM

Calgarysfool my RD did 3rd gear wheelies (no lie). You could pull up in 4th goin' 60 next to some guy on a modern sport, drop a gear, pull the front off the ground and start shiftin up before she flipped over on ya.

A guy I was trading parts w/ in AK was putting 100 hp to an RD 350 Drag bike.

I hope no one understood me to be suggesting any particular ratio. It's just that I seem to run into the misconception of more oil is better in the m/c community and I noticed it a little here. These are obviously not high mileage motors but it sure would be interesting to know how far some of the higher mileage motors have gone and what their owners did to make'm go that far. There are a lot of factors in choosing a ratio and I don't claim to be any sort of expert on the subject, I just have a rudimentary understanding. On unmodified engines, the manufacturers instructions should be accurate. However, That being said These motors are made in China and Indonesia and probably other local's as well. Poor translation into english , quality of oil available in that particular region compared to quality of oil you use, petro vs synth, these are just a few complicating factors. In truth you want to use just enough so that it doesn't seize no matter how you ride within reason. You should use the highest quality oil you can afford and that is readily available to you i.e. don't switch oils often, find a good one and stick w/ it. Some of the race quality oils will give you guidelines to follow. Just like a 4 stroke, your plugs should be light brown but not tan and power should be crisp. If thats the case and you've been ridin' around without seizin' your probably fine.

I haven't read of any seizures so far!

**Bikeguy Joe** · #10 10-04-2008, 05:59 AM

Quote:

Originally Posted by old motorbike

I'm using 16:1 oil the first week and it still 4 cycles some of the time, mostly at higher revs. (isn't that too rich?)

That's too much oil.

If it 4 cycles with that mix, it will surely 4 cycle when you go to 24-32:1 mix.

Most of the "instructions" that come with these bicycle motors suggests using 16 or 20:1 because that would be the correct mix with ancient, 30 wt. motor oil.

Too much oil will cause rings to stick (really bad) and excessive carbon build up.