Blow-by

[breno]

How much blow -by is considered acceptable??

I have the K&N air filter on it so the blow-by just spews out all over the frame.
In a 20min ride I have 2 stroke oil on the seat pole. Looks messy...
Cant say the bikes running bad doesnt tend to like holding the same speed as it will start to 4 stroke but a small adjustment in the throttle and it pulls straight out of it.
Im running 15:1 fuel to oil. Oil is Castrol Active 2T and the fuel is BP 98 octane. Plug looks a coffee colour. Carb 2nd slot from the bottom.

 

[bairdco]

15:1 is a rich oil mixture, and that's what causes the mess. the only way to stop it is to use a different oil and a leaner mix.

i use opt1-2 at 100:1 and there's no mess at all.

 

[breno]

I have done approx 1200km's now. Had been thinking of trying a dif. oil and leaner mix.
Last night I bought some Castrol Active TT-R fully synthetic oil.
Has anyone tried this oil?? Is it any good??
Anyhow I managed to stuff up at the servo and put 200ml into 2.2L. Works out to be 11:1 ooops..
I checked the plug after riding around for an hour or so and it trully didnt look like it was running that rich :/
I'm wondering if the fuel i'm using being 98RON is too spicy.
I reckon if I was to run even 25:1 it would probly give me a white plug.

 

[skyl4rk]

Oil content doesn't have anything to do with running rich or lean. Rich or lean is the fuel to air ratio.

 

[breno]

so is the fuel to air ratio what determines the colour of the plug??

 

[bairdco]

for simplicity's sake, i saId a rich mixture. i guess i coulda said "...an oil rich mixture..." to keep people from correcting my terminology instead of trying to help with breno's problem.

the color of the plug is determined by a few things. the ratio of gas to oil, the effectiveness of the combustion charge, riding style. etc.

the main thing is how well the fuel mixture burns, and that's mostly dialing in your fuel to air ratio.

 

[breno]

thanks bairdco. I think I'll try running 20:1 mix and check the plug again. Being fully synthetic I'd like to think I wont end up with a white plug. Worst case like you said I can always move the clip to the bottom (down 1) adjusting the air/fuel mix and see what happens.

 

[2door]

Oil content doesn't have anything to do with running rich or lean. Rich or lean is the fuel to air ratio.

Just to clear the air, or confuse the issue even more, oil content does effect the fuel mix. The more oil the leaner the fuel to air ratio because there is less fuel (gasoline) to air. The more oil, the less fuel so the fuel mix ratio is leaner than with less oil. The oil, or the majority of it is not burned during the combustion cycle but is there mainly for lubrication. An oil rich fuel mixture will run lean where as using less oil will richen the mix. Confusing, I know but the terminology and the difference between a rich mix and an oil rich mix is important to understand.
Tom

 

[breno]

makes sense.
On another note can too much oil be bad for the motor setting aside it will give a leaner air to fuel mix in the top end.

 

[2door]

Yes, for a couple of reasons, one of which is theory. Fouled spark plugs can result with too much oil and there is good reason to believe that excess lubrication can effect the correct seating of the piston rings to the cylinder walls. Or the so called break-in of the engine. As I said, that is theory and you'll hear conflicting thoughts on that. Nevertheless, using the proper fuel/oil mix is important but not an exact science. You'll see many opinions based on the users success with whatever they have found that woks for them. Like Bairdco, I'm a confirmed Opti-2 @ 100:1 user and have had good luck. I do not however recommend that avenue to anyone; its just what works for me.
Tom

 

[breno]

Thanks Tom. It appears theres alot of people using the opt2 and arent having any probs.
I wouldnt mind giving it a try.
Did you find any increase performance wise from the standard 2 stroke oil?

 

[2door]

breno,
Instead of me giving you my opinion, just take the afternoon and read this> http://motorbicycling.com/f3/100-1-mix-9850.html
I'm sure you'll be able to decide from the information in that thread if you want to experiment with the controversial Opti-2 blend. Lots of pros and cons to look at.
Tom

 

[breno]

Ended up going to 25:1, plug still looks like its got a bit more in it to go to 30:1. The blow -by issue is still present but I think it may have improved a little. I'm not to keen on thought of running 100:1 just yet i'm concerned that I wont be getting enough lubrication through the bearings. Usually I ride at the mid to top end of the rev range.

 

[breno]

turns out that i'm blind or stoopid. found the problem it was slightly leaking from the banjo fitting connection to the carb. I cant believe I didnt see that. Resealed the connection and WA-LA problem solved. DOH!!

On another note the bike is running gr8 atm. Will be running 30:1 on the next tank hopefully it works out to be a good mix. I dred going through so much bloody oil its expensive stuff when u gotta fill up every day.

 

[Alson]

i believe 25:1 is fine for synthetic oil, some people go to 32:1 with good synthetc. I like 25:1 cause I run most of thr time full throtel. Good synthetic oil stays on thr piston walls longer

 

[flybytaco]

breno you can run that castrol 50:1 all day long man you dont need to switch oil 2.6 oz to a gal