Is it possible to get an accurate plug chop when running Opti-2?

GoldenMotor.com

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Petcock/fuel flow has little to nothing to do with plug color.
The old myth that a "high flow petcock" improves or effects performance is only in the minds of those who say it.

Look at it this way and try this experiment: First fill your fuel tank. Disconnect the fuel line from the carb, open the petcock and drain the tank into a container while timing how long it takes to drain. Now compare that time with how long you could ride your bike before you run out of fuel.
I will guarantee you that the tank will drain in a whole lot less time that your engine could burn it.

My point being that the engine can only consume so much fuel per hour. Increasing the flow will have no effect on how much the engine can use. The carburetor float and needle valve controls the fuel flow, not the size of the petcock orifice..
As long as the petcock/fuel line will flow a steady stream, not dripping, it will deliver sufficient fuel.
With this in mind I can only assume that you were running extremely lean do to a lack of fuel in the carb because of the "partially restricted" petcock. That would explain a lean reading on your plug color inspection.
Tom
 
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ToxicAz520

New Member
Mar 11, 2011
288
0
0
Tucson,Arizona
i am using a bh6s plug. its about 100 degress daily in az so i havent tried a hotter plug yet cause i think it would increse the runnning temp of the motor it already runs so hot if i bump my leg on it i get stripes on my leg it dnt blister but it is a little uncomfortable for and hr or so.
 

Goat Herder

Gutter Rider
Apr 28, 2008
6,237
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N.M.
I won't wear shorts on my bikes. Too many BMX stunt accidents as a kid acting indestructible. Plus those hot little china motors got those surprises.
 

onanysunday

New Member
Apr 21, 2011
51
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0
St. Paul
(here we go again) I did not have steady fuel flow due to a clog and chose to replace my petcock, it turns out sickbikeparts had one available and it just happened to be a high-flow version. I understand these bikes run on a drop of fuel with the possible exception of WOT conditions (which is how I normally ride) the problem was I wasn't even getting that. This is petty and I shouldn't have to explain/defend myself because it's not the Spanish Inquisition (although I am Latino). Good luck Toxic, sorry my advice didn't work for you as well as it worked for me-just trying to help (if that's still allowed) Good luck on finding a solution.
 

skitchfish

Member
Oct 27, 2010
222
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Michigan
This blows my theory! I am a newbie and mean no disrespect. I thought my carb bowl was emptying at extended wot thus losing power and coming back on when regaining fuel. I improved fuel line and petcock and problem was resolved but i did do other things. If it is impossible to empty fuel bowl I have misinterpreted the problem and solution.
 

Goat Herder

Gutter Rider
Apr 28, 2008
6,237
20
38
N.M.
This blows my theory! I am a newbie and mean no disrespect. I thought my carb bowl was emptying at extended wot thus losing power and coming back on when regaining fuel. I improved fuel line and petcock and problem was resolved but i did do other things. If it is impossible to empty fuel bowl I have misinterpreted the problem and solution.
Read this thread then. http://motorbicycling.com/f34/your-bike-losing-power-top-speed-24880.html

'''The O.P. are not quite referring to this as their problem''' I think because they say they ruled it out. 2door I think gave a accurate description as well.
 

NorthMi

New Member
Jul 5, 2011
21
0
0
Wexford County, MI
Your plug looks really good, I have a 66 Grubee and it would not run with the original jet size opened up to #66, I have been running the B6HS also but mine is very light tan to white, bought Rec gas (No Alky) and mixed the last batch of Opti2 at 50:1 and the color did darken a little. Have now went back to my old standby Klotz R-50 mixed 32:1 and plug looks like milk chocolate, and the Klotz smells just like when I raced flat track and TT in the 60's, I will try Opti2 in my next build a new but 2yr old 50cc Zoom.
Thanks for the info,
Mike