Do I need new piston/rings

[Bjbarsted]

Ok so now im at #105 main #40 pilot and 1 full turn out on the mixture screw it idles fine i can give it quick successive revs fine just randomly i will get a backfire or bog down at the start of the rev.
Running heaps better now turned the idle screw in another 1/4 turn and the backfires are minimal and only a tiny stumble barely noticeable. Now i guess i just need to be able to take it out for a proper ride and try it out.

Thanks heaps for your help.
Just for future reference what are the main things to look for to tell if its to rich or to lean?

 

[my67xr]

Popping and hesitation can be too lean off idle
Popping can also be valve/rocker clearance's being too tight.


Too lean at 1/4 - 3/4 throttle the engine will sound deep and die off (to fix, richen needle, lower the clip onto the 4th notch down or bottom notch of the needle)
Too rich at 1/4 - 3/4 throttle it will stutter/cough and splutter (to fix, raise the needle clip to the 2nd notch from the top or top notch on the needle)


Too lean in the top end (wot) it will sound deep and die (main jet too small)
Too rich at wot it will stutter/cough and splutter etc

 

[Bjbarsted]

Awesome thanks again that will help to work out what I need when I go for a ride
I might also check the valve clearances just to be sure

 

[Bjbarsted]

Thanks heaps for your healp in this thread my67xr i finally had time to tune the carby today. I have gotten it to a ridable point still needs a little fine tuning but i am actually getting some where with all the info and help you have given me.
One other thing i have noticed with it though is it holds its rev for a second or two after i have let the throttle off. Now i know the slide is returning straight away is there any thing you could think of that may be making this happen? I have gottwn it to a smooth rev range right to the very top end of the rev range but thats just a matter of playing with the needle and main i can work that out but i have no idea what would cause the slow return of revs

 

[gottagetacheaperhobby]

Thats either an airleak or your pilot jet is lean..

Sent from my SM-T110 using Tapatalk

 

[Bjbarsted]

Ok thanks. I'm fairly sure I don't have an air leak so I will go a little bigger on the pilot

 

[Bjbarsted]

Now so i have finally got the bike to run smooth through the entire rev range all that is left is to be able to do a wot chop and see how the plug is.

I ended up at a #38 pilot and a #98 main it sounds really low considering what i hear every one ells running on a lifan150 with the 26mm oko flatslide but its what is working and the needle is in the middle.
I started at 105main like suggested but at the bottom of the needle i couldnt even get to half throttle without it bogging down.
I moved it to the top and i would get to about 3/4 throttle and it would bog down. I just slowly changed to smaller jets move the needle back to the middle every time and then the top to see if it would bog down later in the rev range until i got to 100main and it reved out at the top of the needle so i dropped in size once more and ended up at the midle of the needle with a clean rev range through all gears.
Is this the way ya normally test and tune. And does it sound like there may be some other issue with having the lower size jets?