Running a tad rich

[RagMan]

Which way to tweak the carb, to lean it up a tad. clockwise or otherwise???

[Leonard]

Which way to tweak the carb, to lean it up a tad. clockwise or otherwise???

Are you talking about the idle/pilot jet?  If so this quote from Snidal"s manual would apply:
"The pilot jet is an "air bleed" - tightening it makes for richness, loosening leans it out."

Leonard

[RagMan]

Thank you, that sounds like the thing.  Being somewhat ignorant of technical matters, and foreign, I have no clue what the correct names of things are. The idle is marginally high, which makes starting easier, but running tends to be a bit sooty, and deceleration causes minor soft 'pops'  Unless I am totally wrong, which is possible, such symptoms can be made by a rich running engine.

[deejay]

You can lower your needle too.

[RagMan]

Thank you, deejay, how do I do that..  My P Snidal book has not arrived yet.

[deejay]

I removed my tank to get to the top of the carb. Screw the top of the carb off by hand, then you can remove the cable, and the slide. Under the slide sits the needle, take it out, there is a clip on the needle that you can move up or down on 5 or 6 notches. If the clip is on the bottom notch, it is raised to the maximum, allowing more gas to pass by it. If the clip is at the top notch on the needle, it is at its lowest position, allowing less gas to pass by it.

This may seem confusing, but when you have the top of the carb off, it will become painfully obvious how it works.

[RagMan]

Thank you. That sounds logical. I will try the idle jet tweak, if it still pops, I will mess with the needle. If I am not careful, I will turn into a bike mechanic.

[justin_o_guy]

I thought "Pops" were generally a lean burn indicator. If the inside of the exhaust is dark sooty, then rich it is, but if its got very little soot & its a lighter color, then rich it isnt. A look at the plug might be a good idea, too. Much less expensive then a scorched piston.

[RagMan]

Real sooty exhaust...  someday, when it arrives, I will read the Snidal book cover to cover, at least 10 times, so that I turn into a knowledgeable person..  I unfortunately have limited mechanical experience, most of which was over 30 years ago.

[deejay]

Best way to tell is a plug chop. Make sure the plug is new.

[RagMan]

I will be getting a box of plugs this week so will have me a look see then.

[gapl53]

Remember;
Idle adjustment affects how the engine runs from idle to midrange, changing the needle clip position affects the midrange. The high speed jet effect the engine from 3/4 to full throttle.
The high speed jet should be correct before making any other adjustment to the carburetor.
If the high speed is correct, then adjust the midrange, low speed mixture and idle speed in that order. Just don't have the idle set over 1200RPM when adjusting the low speed mixture. At about this point, depending on needle height, you will start the transition to midrange.

[RagMan]

Thank you for that clarification - I have the Snidal manual on hand so I will be reading a lot from now on.

[gapl53]

For future reference, popping or a backfire in the carburetor is an indication of a lean running, or to far advance timing. Popping or a backfire in the muffler indicates a overly rich condition. But a single back fire in the exhaust when you suddenly close the throttle is normal. This is due to the fact that when the carburetor is suddenly closed for an instant it causes an overly rich mixture because the slide blocks the air flow. The overly rich mixture will not combust in the cylinder under compression due to the lack of oxygen needed. But once that mixture is moved to the exhaust pipe where there is more oxygen available, it has a chance to ignite from the following combustion stroke.
 
I love the art and science of tuning.

[RagMan]

Reading this manual is giving me a warm feeling.. sounds silly, but I think I am going to be able to do this stuff without too much problem.