RM125 jetting help

[railer]

I have a 98 RM125 that I picked up a few months back (the bike actually used to belong to Buddy Antunez at one time), and it has a Bill's pipe and an exhaust which I recently re-placed with an FMF Turbine Core II, because I needed something with a spark arrestor. The bike ran great before I replaced the exhaust, with a 165 main, the needle at pos. 3, and I believe it has a stock slow jet in it. When I replaced the exhaust, the only thing I did to the jetting was take the needle up to pos. 4. I didn't like the way it ran, so I moved it back to pos. 3. I haven't ridden it yet, but I did start it up, and it seems to bog a little during the rev at high rpms, and it's smoking more than I'd like it to. It's a white smoke, and I feel that it's a bit excessive, but that could just be the way the bike runs, I dunno.

I rode it in the parking lot (of my barracks) for a brief minute and it seems like when I run it at low rpms, it's okay, but then when I take it up and let it wide open, it gets choppy. If I keep gettin' on the pipe, it will quit the choppiness and run good. What am I experiencing? Is this normal?

On 125 2strokes, is it necessary to stay in the high rpms range to keep from making high end throttle feel choppy and draggy when you do happen to use it?

Thanks for any input.
Brian.

 

[railer]

Well, I did some more searching today and found a lot of posts on this subject, so I guess I will try some different things. I didn't know I needed to run 40:1 in it. I've actually been running 60:1 and even 80:1 sometimes. I will try doing that plus maybe re-oiling my air-filter becuase I think I over oiled it last time I cleaned it. The bike runs good I guess considering I've been on the same plug since I bought it back in November '05. I guess I just need to stay on the pipe more too, since it seems that the low rpm ranges are screwing me.

One question about that I have is that, could the factors I listed above cuase it to bog during high rpm revs? I would still like to hear my bike scream, and I'm wondering if I should lean it out a bit more. At the same time I don't want to lean it out to much, which I think would cause it to "burn up." Is that what would happen?

Any comments would be appreciated, for I am still learning. My bike mechanical skills are far from honed so anything can help, but I just want to say that this is a great forum with some great people on it, and I'm glad I stumbled across it when I did.

Brian.

 

[Okiewan]

Read this:
http://www.ericgorr.com/twostktech/carbtuning.html

And yes, too lean is bad.

 

[mg89]

For a 1998 rm125 you need to run 32:1

 

[jdc9q8]

I run 32:1 on my 97 yz125

 

[dirtbikegeek]

32:1 is good for all two strokes

 

[+30]

80:1? :yikes:

 

[fallfactor]

with synth. oils go 40:1 any cycle shop will tell you 32:1 is a over kill put on new bikes fuel tanks for new riders - so if the screw up there ratios when starting out they have a safety factor there. But 32:1 is to rich - remeber carbon build up from rich oil mix is harmful to the motor and causes carbon ware on the cyld walls. Grap team green mixes at a little over 40:1 and those bikes are raced at high rpm and wide open
I ride with mechanics that run there bikes at 50:1 with good synch. oils for the life of there bikes and they have longer times between rebuilds then those running rich mixtures.