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YZ144 woods bike build.

By harvmushman,
in Yamaha 2 Stroke

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harvmushman

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I picked up a clean 2006 (first year of SSS suspension) YZ125 for a woods bike build. I have long been intrigued by the idea. My other bikes right now are a YZ250f (269) and a WR450f. The 125 is feather light in comparison.

I sent the engine off to Eric Gorr and asked for the bottom-end power option he advertises for arenacross and woods. Turnaround was within a couple of weeks. Since I sent him the whole engine so he could also grind the cases, it was returned to me completely assembled so I have no internal pictures of his porting or head work.

After install, it did feel like there was noticeable increase in compression at the kick-start. It fired up within a couple of kicks, and purred nicely with no extra noises than previously.

I leaned out the pilot and main jets 1 stop, because my past experience with a big bore (and the experience of others on the forum) is that the big bore actually needs leaner jetting.

The rear sprocket is one-tooth smaller to stretch out the gears a little bit with the change in power.

First impression:

I have only ridden it up and down the street. I will be taking it to a Grand Prix track later today, to get a full impression.

Right off the bat, this has an amazing amount of off-idle power for a 125. The flat spot down low is greatly diminished. The power builds in a linear fashion, with a diminsihed "hit" on the top. It signs off earlier, too, I think. I think it will be a very friendly powerband on the trail. We shall see.

In terms of overall power, it of course does not have the wheel lifting grunt of the YZ269f.

I will post more after a real ride.

IMG_4152.jpg

IMG_4147.jpg

Edited by mgouras
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harvmushman

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I rode it last night on some local trails. To recap: This is an Eric Gorr built 144 with his woods porting, pump gas. Here is my takeway:

_ The mid-range is much broader than stock. You can effectively ride the mid-range on the trails, especially flowing trails with no big hills. There is more bootom-end as well.

_ Big hills still work best riding the pipe.

_ If you fall much below the mid-range, it can get flat pretty quick! It is still a tiddler.

_ It builds to a nice top-end, I think. the hit entering the top end is fun, but not large by any fashion. More like a pull. Very good for the trails. It pulls longer and harder on top than I would have expected out of the porting option I picked. But it has less hit than stock and probably signs off earlier? Hard to say for sure.

_ The engine starts super easy. A half kick does it.

_ My friend was on a KTM 250 XC-W. We switched. The comparison? The KTM has much more down-low grunt, and really more power everywhere. The YZ144 weighs less, and can be more easily flogged and flipped around. What did you expect! I also liked the SSS suspenders better.

Edited by mgouras
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MANIAC998

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I got a chance to ride mgouras 144 today at Pipestone, Montana. Absolutely incredible! The bike has ample bottom end power to haul my 200 lb frame around, and has a very nice mid-range "push" as I don't want to call it a "hit" as it doesn't "hit" at all, it just starts coming on very well and has tremendous pull. And the top-end was very good too!!! All in all, I was so impressed, that I'm planning on doing the exact same options from Eric Gorr on my '01 YZ 125 and use that as my race weapon for this upcoming season. I might not get the greatest results racing the 144 versus my WR450, but that little Yamaha will teach me how to be aggressive again, and it's a HOOT!!! And racing a bike that will effectively be near 70 lbs lighter than my WR will be a blast too!!! Thanks mgouras for letting me take your bike for a spin, and sorry about running into you!!! ? Maniac

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Travis147

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I have an 07 Eric Gorr built 144 ported for woods as well. I have 3 full rides on it and absolutely love it. One ride spot is very tight and technical and the others are more open and flowing. Normally I ride a 450 in woods and do fairly well with it but get tired quickly. On the 144 I can't stop smiling the entire ride and have plenty of energy. The power is butter smooth and easy to control. I can abuse the clutch and it doesn't heat up. I left the gearing at stock, If I were going to do more mx with it I might gear it taller but with the 6 speed tranny- stock works great for woods. The only downfall is it guzzles premix. I need a bigger tank and will pick one up as the wife/budget allows. So far I'm very satisfied and recommend it to anyone considering this option!

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rjpjnk

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I also have an 06 yz125 that I am considering sending to EG for a 144. Trying to decide which porting option to go for (for light MX, backyard track and trails fun, older rider). I was talking with Eric yesterday and he told me the low-mid option can be converted to the mo-better option by just adding 2 additional base gaskets, but to go the other way would require sending the cylinder back in to get milled. He said the 3 gasket setup would be "very close" to the mo-better option but not exact.

I am leaning towards the low-mid porting because of this flexibility. My only concerd was loosing top end (which is really nice on the bike now). I would like to hear more about how much is left after the port. So 2 riders on here already have it and really like it? That is such great news! Feeling a little more confident about doing this now.

The OP rejetted leaner. How's that working out? Are you at 35 pilot now? main?

How about Travis 147? Any changes to your bike for the porting? Jetting/Pipe/Reeds/gearing?

Thanks so much,

RIch

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LazyWaffleman

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I got a chance to ride mgouras 144 today at Pipestone, Montana. Absolutely incredible! The bike has ample bottom end power to haul my 200 lb frame around, and has a very nice mid-range "push" as I don't want to call it a "hit" as it doesn't "hit" at all, it just starts coming on very well and has tremendous pull. And the top-end was very good too!!! All in all, I was so impressed, that I'm planning on doing the exact same options from Eric Gorr on my '01 YZ 125 and use that as my race weapon for this upcoming season. I might not get the greatest results racing the 144 versus my WR450, but that little Yamaha will teach me how to be aggressive again, and it's a HOOT!!! And racing a bike that will effectively be near 70 lbs lighter than my WR will be a blast too!!! Thanks mgouras for letting me take your bike for a spin, and sorry about running into you!!! ? Maniac

I had the 144 put in my 00 and I can say that its one fun bike on race gas and mid top porting. Its really seems like alot more power up top and everywhere with that old motor. Cant wait to hear what you think of yours.

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MANIAC998

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Well, mgouras's YZ144 actually isn't doing very well at all. He woke up to a garage fire this weekend, and he lost all of his bikes, including the EG YZ144!!! Two weeks before the start of our race season too!!! He's seriously bumming right now! As for me and my '01, I'll get the same Low to Mid porting option, because it is so flexible and truely can be ridden effectively off-road, and that's where I do all of my racing. And also because I've never been the type to be able to keep a bike "singing" on the pipe. I'm a lugger/torquer. Maniac

(now I don't feel as bad about running into him and his pristine YZ144!!!)

Edited by MANIAC998
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Travis147

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How about Travis 147? Any changes to your bike for the porting? Jetting/Pipe/Reeds/gearing?

Thanks so much,

RIch

EG ported it for MO beta I believe. I have a Fatty pipe and shorty silencer. There is a reed spacer that was in it when i bought it, I left it in. Jetting is 45-430. I'm at 500'. I run Spectro SX2 32:1 with minimal spooge on premium pump gas-no ethanol. I run ATF F tranny oil. The only issue I have is the idle is tough to get dialed in. It seems to always idle fast or not at all. I may have a small air leak, possibly at the reed spacer that could be contributing to the fast idle.

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