05 cr125r jetting

[8950]

hey, i just put a fmf fatty pipe and silencer on my 05 cr125 and i keep fouling plugs. i dropped the main down from 430 to 420 and i still foul plugs. anyone out with an 05 and pipe? i live in chicago and never had to deal with jetting, fmf does not list an 05 jetting chart... any one know how low i have to go on the main and do i have to change the slow jet also? it does load up on me when it idles.thanx

 

[8950]

Anyone?

 

[Rich Rohrich]

it does load up on me when it idles.thanx

Then you should stop worrying about the main jet and work your way up though the circuits starting with the pilot jet.

http://www.ericgorr.com/techarticles/carbtuning.html

 

[MXP1MP]

my friend has an '06 same bike as your's so far we have dropped the pilot two size from #55 to a #45 and went to the next size leaner needle in the 3rd clip air screw at 1.5 turns out and it's starting to clean up nicely now oh ya btw it has an FMF pipe too. He said that was a waste of cash but just didn't want to smash up the stocker since they are so expensive.

 

[canadian-dirtbik3r]

I just installed the fmf fatty with turbine core 2 but havent runned the bike yet. My pipe came with a jetting guide thing with jetting recomendations from fmf. Should i use it as a starting point? This is what it is

Main Jet: 172
Pilot Jet: 58
Needle: R1468N
Needle Position: 3RD
Air Screw: 1.5

And any tips for the colder weather that is coming our way? What am i susposed to make leaner?

 

[Sayntmatt]

When I got my 05 CR125 earlier this year it started fouling plugs so I dropped the needle one notch and dropped the main and pilot by one size each and it was pretty good at that. Recently tho I have put a full system on although mine is a DEP system. This made it run a bit leaner so now I have raised the needle back up one, gone one bigger on the main and left the pilot alone. It seems to have done the job! When first started tho and after just sitting on the gate with relatively low revs it does need its throat clearing but after that and especially when on the pipe it has made a good bit of difference!

 

[MXP1MP]

Stock jetting the plug comes out black before the bike was even ridden dropped the pilot to a #45 to make it leaner you can hear it clean out and pick up sooner. With the rest of it left stock the plug came out black still but not as bad. The tried moving the stock needle to the 2nd clip alittle bit better but the plug was now more like a dark gray. Thats probably why your bike loads up on the line man and has to be revved up to get cleaned out your loading up. Still haven't gotten quite to the TAN color you want yet with the bike but need to do a new test run with the leaner needle on a fresh plug to double check how close it is. It still has alittle bit of bog hesitation after hard landings and sometimes it spills gas out of the overflow tubes going to make sure the float height it right also.
ahh the joy's of jetting :)



Current spec's
PJ #45
Needle # 1369 in the 3rd clip position (stock is a 68) you go up in numbers to get leaner (it might be 1468 is stock and he went to 1469) not my bike but you get the point. I dont have the manual in front of me.

Main #430 - that is stock

 

[8950]

Hey, I Dropped The Main Down To 410(stock 430) And The Slow Down To 50(stock 55)didnt Have To Mess With Needle, The Plug Looks Fine And The Power Is There. If Someone Put A Pipe On And Didnt Notice A Difference, Something Isnt Right. I Feel A Big Difference From Stock To A Fmf Fatty....

 

[MXP1MP]

haha I know what i'm doing the stock honda pipe is damn good it's hard to beat me and the owner of the bike concur it did nothing or very little he's ridden it more than me he "thinks" it might come on the pipe a tiny bit earlier but I couldn't detect any difference just felt the same to me. The jetting mades the biggest improvement.

 

[marcusgunby]

That is true so much of the time, $150 pipe does almost nothing but good jetting can give you about 3hp more and save you $150 in plugs, a little ironic me thinks.