Jetting help..

[Joe_148]

Heres the deal..I got a new 2005 CR125. The first few rides it was running really rich, fouling plugs etc. I put in a #50 pilot (stock #55) and a 420 main (stock #430), I also leaned the air screw out .5 of a turn. I didnt get at the needle because the 05 has a throttle position sensor attached to the carb that im not too sure about and I thought I would just see how it ran with the new jets. I was riding last night and it was running great, however I checked the plug a few times and it was greyish on one half and white almost on the other side (this was a plug that didnt foul but was rode with when I had the rich jetting) I was however riding in deep sand, but after I seen the plug I stopped and just cruised around because I thought I was going to seize up..then what do you know, after just messing around/looking for new lines and jumps it fouls!! After that I just rode normal (not in the sand though) and it ran great, but a few times when I was cruising again, it loaded up and almost fouled, but I managed to clear its throat and save the plug. On the way back to the truck theres a long straight trail and I decided to test out the main. I rode in 5th gear pretty much tapped for about 3-4 seconds, pulled in the clutch, killed it etc..the plug was the same as before, white and gray..however this was with a used plug..but still Im so afraid this new engine isnt getting enough lube..but then it loads up a bit when Im just playing around..think putting the air screw back to stock (1.5) would help a little? I really dont know what to do because I experienced both extremes yesterday (lean and rich) so Im pretty confused.. how good of an indicator is the plug end..because the bike ran great besides the one foul..thanks for your time

 

[rm_racer]

To read the main you have to look at the bottom of the ceramic.

Plug Reading 101 Read this, good info on jetting and plug reading.