try your needle on the 4th or 5th clip, but also jet up at least one size and see if that will color your plug a little darker!

 

White plug is not good. Jet up before you lunch your engine. Do not lean anything until you darken up your plug color. Is that 11/1 piston actually a 10.75/1 JE?

 

The 686 Kit is from MAX POWER. It is a weisco Piston. They say it is 11:1. Check it out.


http://www.maxpower-engines.com/

 

OK....I went ahead and pulled it down again. I can't find anything wrong.

The rod and wrist pin feel good.

I measured Piston clearance. At the bottom of the skirt there is .002 clearance. At the top of the piston, there is about .015 clearance. In the middle of the piston about where the wrist pin is located, I get .010. Obvisoly, the piston is tapered at the top. Is this normal?

Also, the comp rings are rotating in their grooves when it is running. The gaps are not in the same place that were when I installed the cylinder. Is this normal?

The Cylinder ID at the top is 4.015 at X and Y measurements.

At the bottom of the cylinder, I measured 4.015 and 4.020. The 4.020 was the measurement front to back with respect to the bike.

Is there anything else I should check?

 

The clatter was piston slap. A cylinder bolt pulled out and tweeked the cylinder out of round. I think this happened because I did not check my ring gap. When the cyl heated up, it grabbed the ring and pulled the cylinder bolt out.

Got a new cyl, checked the gap this time...had to do some filing. Sounds good now.