Is my fuel air mixture good based on spark plug?
- Thread starter StrontiumEthics
- Start date
a/c man
Member
Looks a little on the rich side to me.
How's it running in your opinion?
Is it 4 stroking or stuttering at full throttle?
The picture would tell a little more from a side view of the plug.
You want a chocolate tan color on the insulator.
I'd probably lean the main jet a little.
How's it running in your opinion?
Is it 4 stroking or stuttering at full throttle?
The picture would tell a little more from a side view of the plug.
You want a chocolate tan color on the insulator.
I'd probably lean the main jet a little.
StrontiumEthics
Member
Its Very funny. I just adjusted the Needle and took that last picture from the first post. Before that point the engine was stuttering @ Full throttle when I rode. I was getting the idea that it needed a little more fuel. So I lowered the e-clip to the 3rd out of 4th slot on the needle, and tested it. I didn't really get a chance to test it with the engine on the 3rd notch (The two attached pictures) because it began to get dark outside. But while the engine was on the 2nd notch it stuttered while riding at full throttle. Here is the picture from the side you requested.
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a/c man
Member
Oh yea, way to dark and oily. You'll foul that plug quickly that rich.
Remember that the needle jet will only regulate the fuel mixture to about 2/3 throttle. You can move the clip to the top notch and still be running too rich at wide open throttle with too large of a main jet.
When you did your plug chop test at wide open throttle the needle jet didn't even come into play.
I really think it's time to play the which size main jet do I need game. Experimenting by soldering the jet shut and re-drilling is the easiest, quickest and cheepest way.
There's lots of posts here about that or e mail me if you want.
I've got mine just right and the difference is remarkable.
Tim
Boell4grumpa@aol.com .....if you need to
Remember that the needle jet will only regulate the fuel mixture to about 2/3 throttle. You can move the clip to the top notch and still be running too rich at wide open throttle with too large of a main jet.
When you did your plug chop test at wide open throttle the needle jet didn't even come into play.
I really think it's time to play the which size main jet do I need game. Experimenting by soldering the jet shut and re-drilling is the easiest, quickest and cheepest way.
There's lots of posts here about that or e mail me if you want.
I've got mine just right and the difference is remarkable.
Tim
Boell4grumpa@aol.com .....if you need to
StrontiumEthics
Member
Wow! Really? But very strange. When I had the E-clip on the second notch and did the same test the spark plug came out pretty dry, not so oily. So do you recommend going down on my main jet? I don't mind getting some jets from SBP? But from what do I start with? which jet do I have now?
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The most common jet size is a 70.
I say most common size because the actual jet size seems to vary a little with different kits, manufacturers, and the particular day of the week that the carburetor was assembled.
I say most common size because the actual jet size seems to vary a little with different kits, manufacturers, and the particular day of the week that the carburetor was assembled.
a/c man
Member
I really should have asked what ratio you are mixing you gas and oil.
A "thick" mix will look darker than a 24:1 mix for example.
Like GearNut said stock is around #70 (.027 inches)
Most stock jets run too rich.
Try a #68 jet see how it works.
If you want to try drilling here's the resource I use for converting
drill size to both millimeters and decimal inches.
It's about half way down the page .DRILL BIT CONVERSION TABLE
http://en.wikipedia.org/wiki/Drill_bit_sizes
A "thick" mix will look darker than a 24:1 mix for example.
Like GearNut said stock is around #70 (.027 inches)
Most stock jets run too rich.
Try a #68 jet see how it works.
If you want to try drilling here's the resource I use for converting
drill size to both millimeters and decimal inches.
It's about half way down the page .DRILL BIT CONVERSION TABLE
http://en.wikipedia.org/wiki/Drill_bit_sizes
motorpsycho
Active Member
yes, also remember that when you go to a smaller jet, one number size difference can make a huge difference in the air/fuel ratio. you may have a 70 jet now, but if you drop to say, a 65...that's dropping way too many sizes all at once. when you lean out a carb by changing the jet size, you need to go in tiny increments.
like a/c man said...if you have a 70 jet, only drop down 2 sizes to a 68 and try it.
i think i need to re-jet one of my carbs too, but i am running 16:1 gas/oil mix for the break in period so i won't really know if i have to lean it out until i can drop to 20:1 or 32:1 gas/oil mix.
like a/c man said...if you have a 70 jet, only drop down 2 sizes to a 68 and try it.
i think i need to re-jet one of my carbs too, but i am running 16:1 gas/oil mix for the break in period so i won't really know if i have to lean it out until i can drop to 20:1 or 32:1 gas/oil mix.
StrontiumEthics
Member
As of now I am running a 20:1 ratio and I put the notch up to the Second to first notch. and ran the engine for quiet a while and then let it cooled and took this picture of my spark plug. Tell me what you guys think. I was going full throttle a lot while riding.
PS: Something strange started to happen. While riding when I release the throttle it took a little while longer for the bike to idle. Perhaps an air leak in the carb?
PS: Something strange started to happen. While riding when I release the throttle it took a little while longer for the bike to idle. Perhaps an air leak in the carb?
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a/c man
Member
It looks better.
How did it run?
How did it run?
