Ran well during break in-hard start after leaned out mixture. . .

I have a Grubee Skyhawk that just had a cylinder and piston/rings replaced. I've been running 24:1 for nearly 2 gal tanks, keeping it under 20mph for at least 1.5 gals. It was running very well. Started like a top on the first clutch release every time and didn't kill. I started to open it up toward the end of the 2nd gal and I was getting great throttle response and about 30-33mph out of it consistently and was running intermittent WOT for the next 20 miles or so. I had at least 100 miles of taking it relatively easy.

I leaned the mixture out after that to 32:1 and lost some performance and had harder starts. I figured it might be bad carb adjustment. I understand that leaning out a mixture generally allows more gas through, so I initially adjusted the needle down one notch (moved the clip up). I was able to get it started, but it started very hard (only after pedalling a ways with clutch engaged) and had much poorer performance. Now only about 25mph and sluggish. The plug seemed to look rather grey. However, since performance went from bad to worse, I adjusted the needle the other direction, moving the needle up (clip down) to the position just below where I had it for break in. I am now on the bottom clip position on the needle. It will again barely start. Anyone have any suggestions?

FYI: You might also like to know . . . when we were installing the new piston, it was bottoming out on the cyclinder head. The new piston was apparently taller than the old on. We had to install a couple of extra gaskets and shave some aluminum off of the head to get it to fit. After this, it seemed to be running fine till I switched the fuel mixture.

Any help is greatly appreciated!

Well . . . I may have found (a big) part of my problem. The guy who fixed my piston and cylinder didn't lock tite the cylinder head bolts and they loosened up, resulting in a massive leak. I plan to get a torque wrench in order to lock tite them and tighten all to the same torque. Then we'll see what happens!

Does anyone know how tight those nuts should be?

Also, regarding the mixture, my plug was actually very dark at first the the carb needle in the 2nd highest (clip on 2nd lowest) position with 24:1, but looked closer to grey when I moved the needle down one notch (clip up one notch) and ran 32:1. Theoretically, the leaner mixture should let more fuel through the carb, which would make potentially give me too much fuel at the same setting, right? However, I'm guessing if my cylinder head had a massive leak (I could feel it all around the cylinder on my legs) that would mess with the carb tuning, right? I did notice some fuel had leaked out of the cylinder head gasket. Any other thoughts on this situation? I'm hoping things will be ok once I get everything tightened, torqued, and locktited.

When I had the cylinder head off, I ran my finger around the cylinder and could not detect any areas of scoring or irregularities. It looked pretty good. There may have been some light scratching, however. I'm not exactly sure what the cylinder is supposed to look like.

Any help or opinions offered regarding this situation would be great. I'm learning a lot about these engines lately, but don't want to learn more the hard way!

Thanks!

Eric

Hmmm . . . Could I trouble for another question?

Wayne-Thanks for all of your responses so far-I appreciate the input.

I got the cylinder head bolted back on and took the bike out for a couple of miles.

I put the carb needle all the way up (with clip as far down the needle as possible). This should give as rich a mixture as possible, right? I have the triple pronged spark plug and am now running 32:1 Penzoil 2 cycle oil. I still can't seem to get the ceramic on the spark plug to turn any darker than like a darkish grey. Doesn't this seem funny, or am I adjusting this wrong? It seems like 32:1 is a very common mixture. Everyone on here says to go by the color of the spark plug for carb adjustment, however this doesn't seem to hold true for my bike. I've also lost about 5mph top speed, which seems funny. The only changes lately are re-tightening the cylinder head, replacing a leaky exhaust gasket with a new one, and changing the fuel mixture from 24:1 to 32:1 as described above.

Do I need to run more than 2 miles before re-evaluating the spark plug, or is something else going on?

I know this is a lot to read. If Wayne or anyone else could take the time to offer a newbie some suggestions as I work through this, I would really appreciate it.