kx112 jetting help

[SAPPER]

We just finished my sons kx112 build. Trying to get a base jetting setup. stock pilot is 45. main is 138. On and initial run on the stock stuff cause I know that the kx100 is factory rich. It was pretty lean. So I went up 1 size on pilot (48). Then to get some color on a new plug went to 145 main, then 150. 150 seemed to get a dark gray, gettin to brown. The needle is still at 4th down.

The main problem is it loads up if it idles for a few seconds then will clear up if I hold it wide open. BUt it also lost all top end rev. It's lacking alot on the top.

If anyone out there has or had one, I'd just like to know what you had for jetting. My el. is 800'asl

 

[fisher54]

My daughter has a KX 100 a 2008 we bought new. It is still stock except for the gearing. She has bumped up her ridding skill level several times since we got the 100. Each tim I had to rejet. She quite literally operates this bike at full throttle max rpm. I still use the stock 45 pilot but have had to go to a 152 main to keep her plenty of fuel and to keep the engine cool. Her bike does very well and does not load up and idles very well. you might try the stock 45 pilot again and adjusting the air screw 1 1/2 - 2 1/2 turns out . It is hard to compair 1 bike to anoyher because of how the bike is ridden. Being more aggrissive will lead to needing jetting changes. When the bike idles it uses the pilot jet, arround half throttle it uses the needle jet and beyond thet it uses the main jet . Thats how to start , at the bottom and work up to the main jet to get it correct. Again I would put the 45 pilot back in and go from there since your problem is not at full throttle.If the bike blubbers at full throttle the main is to big. If it falls flat like boging on top ,then you need more main .Jetting is time consumeing but nessassary.

 

[whenfoxforks-ruled]

Adjust the air screw till it idles the highest, shut it off and count how many turns out you are at. No top end, the main is incorrect. If you see color, with out a plug viewer or cutting the plug open, you are likely way rich. Lean is real erratic revs, not necessarily a dry plug. See post #17, http://www.dirtrider.net/forums3/showthread.php?t=172481&highlight=spankys+jetting+guide . Vintage Bob

 

[SAPPER]

Well, here's the update. I got the jetting pretty much lined out. 155 main, stock pilot, needle on 3rd position. Here's the kicker. The rings didn't seat. had too much blowby. So, off came the cylinder, Honed it, new rings. She screams.

If anyones interested, Lilse make a hone and stones especially for nikasil coated cylinders http://www.northernautoparts.com/ProductDetail.cfm?ProductId=2104

The bad part is, the tool itself is pricey $150.