Any info from people around here? I have settings for the race gas head but I'm running the pump gas head. Taking it out for the 1st time this weekend and would like a good starting point.

I'm the one who gave you my spec's for the race gas setup for the gorr 144 they maybe a little rich for ya but it will get you close may have to go down like one on the main. Your gonna have to dail it in with some trail n error when you big bore the 05+ yz 125 it needs richer jetting spec's over stock. There was some bad info on there guys said I could run stock jetting with my 144 some crap about bigger bores requires less fuel.

I took their advice and it seized the bike in under 30 mins of run time lucky it was a light one sent the jug back to gorr to have it honed and he gave me a new top end kit for free and said to go up at least two on my main jet. So if my specs are too rich and you foul a plug be glad you didn't have to deal with what i did.

I have been running my bike as a 144 since jan of '06 and it has been reliable for me.

Just ask waunch I am currently rebuilding my 144 right now I had eric remove my orginal crank from the bike and when he pulled it out said it was still good. I have had the bike since July of '05 and have put MANY hours on it mostly moto laps.

Go back on thumper talk and re-read some of the current 144 posts and you'll see that the guys who didn't properly rejet siezed their crap up like me. I told them to go richer and they didn't listen and learned the hard way.

They also got the 14t front sprocket thing from me as well and running the V3 etc. as the first one to run the TiN ring in the 144. But for some reason they hate on me cause i'm not all trying to sound cool cause i'm not out measuring everything.

I have a lot of hours on my bike I would say it had easy 300 hrs and now that it's rebuilt it's ready to rip again for just as long! I was one of the first guys on thumpertalk to 144 his 125 at the time I knew of like two other guys on there that had done that to their '05's.

This message has been edited. Last edited by: joe439,

Thanks yeah I put the 460 main in, 50 pilot, stock needle 3rd position. But I also bought a 440 and 450 main and 45 pilot. I'm running castrol 927 40:1. 14-49 gearing. Bought the 125 for 2600 2 months ago and ended up being trashed I've put 2k into it so far.

I also run 927 at 40:1

If you really want to dial it in, do a google search for wet line jetting. The best way to jet a bike. Takes a bit of time but it works. After that, it's a matter of math to tweak the jetting for various temp and humidity.

How'd it go?

I took it out to riverdale this last weekend. By far funnest bike I have ridden in a long time. That jetting was nearly perfect it ran awesome and really crisp. I brought a 45 pilot and 430-470 main with me but stuck with the 50 and 460. My plug looked safe. Only complaint is how short 2nd gear was going out of corners, guess I'm just so used to carrying 3rd through them in my built 250f. I was running the 14 49 combo.

I had so many issues when I bought this thing. New cylinder, piston, clutch basket and hub, carb float and float needle, reed petals, cables, tires, had wrong wheel spacers on the front, wheel bearings, ace hard wear bolts all over it, tranny bearings, new crank, chain and sprockets, suspension bushings-seals and oil. I could go on but pretty much I got screwed on this one but after like 2500 its all fresh. How often do you change your ring and piston?

To bad I didn't know ya needed a clutch hub I have the oem one from my bike that was prefect shape took it out long while ago and i'm using gyt-r hub now.

Top end life will depend on a little bit on the piston your using and ring.

I have only ever used gorr's 144 piston in my bike. It is his design you can only order it from him. It is similar to the wiseco GP pistons but not the same. The top of the piston dome is coated. The intake skirt is shorter even compared to the wiseco gp piston the gorr piston has a shorter intake side. He also says that the lug area's on the inside of the piston are alittle bit bigger and thicker then a standard piston.

He claims this is to help keep the piston from wanting to knock back n forth.

The biggest wear point on the piston is going to be your exhaust port side. Especially where the cooling holes run parrell with the exhaust port bridge.

What you will see if cause when gorr ported it for mid/top he made the exhaust port smaller in width. So the piston ring will tend to wear a flat spot on in this area only! the rest of the ring seems uneffected.

When I was running the standard non TiN ring I could get maybe 30 hrs out of the top end if I pushed it but the pistons didn't come out looking so awesome.

I was getting vertical marks on the piston and it was starting to leave small bits of the piston on the cylinder wall I was having to clean up every top end.

It was never really an issue for me but I could usually tell it was at that point cause compression would drop off.

I send my cylinder back to gorr along with like 3 pistons and all he did was hone it out for me. Said everything was within spec but said I should be swapping the ring out every 10 hrs.

At that time is when the TiN ring had just become avil for the 144 piston. I ran that piston with that TiN ring as hard as I could for 30 hrs.

I pulled the pipe off cause I was getting parinoid expecting to see blow by like usual. But there was no blow by at all the piston looked clean and the bike was running great. So I threw the pipe back on and ran it for at least another 20 hrs.

I finally pulled it apart cause I had go twice as long as usual and thought I was gonna squeak the motor.

I was pleasantly surprized the piston showed minimal wear marks. There was a wear mark you could see on the piston where the exhaust bridge was but there was no actual scratch / mark on the piston.

The only wear was in the exhaust bridge spot on the ring the TiN coating had started to wear off and was almost all gone and the ring was starting to get that flat spot again.

So I am gonna stick with the TiN coated ring even though it cost more it is worth the cost. It's also why I have 3 standard rings unopened

Here is a pic of the last top end from the bike it only had about 35 hrs on it. As you can see in the pic the vertial mark area i am talking about. That mark is only visable I could not feel it by hand not like with a standard ring it would of had marks into the piston.

Wow well I will be goin with that TiN ring next time. Going to swap out the ring at 10hrs then piston at 20 hrs.

take some pic's of the ring and piston when you do wanna see how it is wearing. don't clean the piston pic's and some of them of it cleaned.

I just pulled my pipe to replace water pump seals for the 2nd time in as many rides. Shined a flash light up there and mine has some vertical marks on the piston. Is this bad? Only has 2 hrs time on it. Jetting is rich if anything still running a 460 main and 50 pilot. I tried to get a good pic but couldn't with my phone. The bike runs awesome by far funnest bike I've had!

Yea it's bad I saw your pics on TT and all I have to say is you didn't properly heat cycle the bike.fresh bore like that you should of let it just warm up and idle and keep rpm's low so that way an initial expansion of the cylinder and piston can happen.

But from what i saw on tt you warmed it up and then went ripping on it lucky you don't lock it up.'jetting is fine you made a rookie mistake there clean it up and take more care in warming up the bike an if you hone the jug those dark heat marks will not go away.

probably wont help but I always ran a castor based bean oil (Blenzall) in my 125's. I found I could go way longer between rebuilds. The difference was fairly dramatic. I was always surprised how little wear on pistons/rings when I measured them. The various castor oils today are degummed so it prevent power valve gumming etc.