2001 CR125 jetting help

[Micahdogg]

Just picked up a used bike that appears to have never been worked on.  Was very hard to start, but ran and shifted fine.  Did comp test and showed 100 psi.  Bought a new pro-x piston, ring, wrist pin, mic'd cylinder and it was within spec and fairly decent (half cross hatch worn away).  So it got cleaned, pv decarboned and put together with at BR8ES.

New filter, new boyeson ss glass reeds, mikuni carb fully cleaned and changed jetting from 380 to 350 on main and from 45 to 40 on pilot.  Clip remains at 3rd spot.  Started right up, but couldn't dial a dead spot out right off idle.  The AS was 2.5 turns out as I lost track where I was (tuning in the dark) and when I turned it in to 1.5 turns it got much better, but when you whick it the thing will still innitially fall on it's face.

Runs good through the rest of the rpm, plug is burning very crips (light tan), no spooge, so I'm happy about all that.  Since the low end got better by richening it up, would you guys think I need to go back to 45 pilot, or adjust the clip a little richer?  I just can't understand why it would like going down on the main so much, but virtually stock on the pilot?  That seems weird to me.

Oh, gas is Klotz 32:1 with premium.  Mods are just fmf SST, silencer and the twinair filter + boyeson superstock reeds.  thanks.

[SachsGS]

Wait till Supertrucker sees this. In the meantime I'd go richer on the pilot. When engines wear out they require increasingly more fuel to the point where they are completely wore out (no compression)you have to lean them out again.

[Stusmoke]

when you wick the throttle, how far back are you pulling it? Your needle could be too rich.

[arnego2]

With an SST I would rather lean into the rich side of jetting than going leaner. I would try for a different needle.
Pistons, the pro x lite come in different sizes, at least for Yamaha, what brand is your bike?

[Micahdogg]

It's a Honda and standard bore.

When I whick the throttle it seems almost immediate.  I can't recall if it was 1/8th or 1/4, but it seems like you can't turn it fast enough to get into another circuit and let it recover.

[Stusmoke]

when you're going wide open, all jets are active. I think. If its fine up until the needle kicks in which I THINK is about 3/8s or something and then it dies, go leaner on your needle. DON'T over do it and bear in mind what arnego2 said. SSTs have a very steep angle and they've been known to melt pistons because the jetting was richened accordingly.

Be careful and don't thrash it until you're certain its not lean on any of the jets.

[Micahdogg]

Went back to the 45 pilot before even trying the clip.  The clip just felt like it would be a bandaid. 

Bike runs much better....there is no more cutting out when you wick the throttle wide open, and IMO it feels a little stronger on the bottom.  Everything is just better going up from 40 to 45 on the pilot.  Only thing that is weird is the a/s is 2.25 turns out and I thought the rule of thumb was 1.5 turns out.  The 40 pilot ran best at 1.5 turns out, but never ran well.  I don't really care where the a/s ends up being as long as the bike runs good, but everything I'm seeing still indicates the 45 pilot is too big - I just couldn't get it to run right on the 40.

[Stusmoke]

I have the exact same bike and 2.25 turns out is well within the adjustment zone. Standard is 2.5 turns out according to my service manual.

[Micahdogg]

Good to hear.  What sizes are you running on the pilot and main?

[Stusmoke]

I honestly couldn't tell you. I know its just a wee bit too rich, but overall its good. But I don't actually know the sizes. When I was cleaning out the carb I neglected to write the sizes down.

Aren't I clever?