[Dgrdurham88]

Bike runs really pretty good for the first hour, then acts like a bike with fouled plugs, and sure enough when I pull the plugs they are covered in black deposits. A quick clean and voila all is well again for another hour. I bought the bike last month, and after cleaning the carbs I find it still has the stock jetting. 35 pilot, 68 & 105 mains. I live at roughly 7000 feet, and that coupled with the heat of summer is the problem I’m sure so I order new jets from Jetsrus.com. I’ll be trying 62, & 95 mains. There wasn’t any smaller pilot jets available unfortunately. Any of you ever seen plugs that show obvious heavy fouling but stark white at the tip like mine? That is from a 20 min ride all over the throttle range. Once I get the new jets in, I’ll do a true WOT plug chop. Just FYI valves are adjusted, cam chain tensioner adjusted, and timing checked with a light. It is advancing properly. Still running points. I would greatly appreciate any sage wisdom from you gurus.

 

[Dgrdurham88]

Here’s the other plug. Also forgot to mention compression is acceptable. Both cylinders within 2 psi of each other.

 

[J-T]

Your WOT plug chop will only tell you your condition at WOT. Few of us spend most of our time riding there (though we might wish to).

You need to do a series of plug chops after a thorough tune up and ensuring stuff like the float settings are correct.

1. You need to adjust your idle mixture screws to achieve highest idle and ensure your carbs are properly synchronized. (procedure discussed here many times, but we can explain if necessary).

2. With the bike thoroughly warmed up, put in a new set of plugs, start if, and let it idle 5 minutes. If carbs are properly synchronized and mixtures are adjusted these plugs should look perfect. Depending on how subsequent plugs look, I might not get real uptight about idle plug readings.

3. Put in another new set of plugs. Ride for 5 minutes at a speed that has you operating on the slow jets, perhaps 1/4 throttle in 3rd gear. Chop.

4. Put in another new set of plugs. Ride for 5 minutes at a speed that has you operating on the primary main jets, perhaps 1/2 to 2/3 throttle in 4th gear. Chop.

5. Put in another new set of plugs. Ride for 5 minutes at wide open throttle in highest gear to ensure you're operating on the secondary main jets. Chop.

Reading each set of plugs can tell you where your problem is.

The 350 gurus may have better suggestions as to how to ensure you're checking each set of jets but this is the general idea.

 

[outobie]

youre on the right track...also make sure your air filters are clean and new