Eric Gorr YZ144 -- 2 Strokes ain't dead!

[lwsmithjr]

For all of you that think the 2 stroke can't be competitive in modern MX..........

My 19 year old son has been racing for the past 6 years. he started out on 80's, moved to a 125, then like everyone else, a 250F. At 15, the awful parent that I am, turned all of his racing expenses over to him. He paid for bikes, maintenance, practice and race fees. I got him to the track and back, but he handled the rest. (I did provide the lawn mowers for his grass cutting business just so you won't think too bad of me). He bought the 250F in August of '03 right before the '04's were released. He bought a Yamaha and for the most part, it held up to it's reputation as being reliable. He broke 4th gear twice in the 2 1/2 years he owned it, replaced the valves w/ Kibblewhite stainless, plus three top ends --$2400 to $2600 in engine maintenance.

January of this year, he decided it was time to return to the 2 stroke. Weary of $1k a year maintenance and trouble getting it re-lit in the heat of battle, he bought an '05 YZ125. Stock, it's a great 125. But in the world of 4 strokes, a less capable rider can turn faster laps. One slight lapse of concentration and the guy behind you is now in front. He was just about ready to go buy a 450 (forget skill, gimme horsepower!) I convinced him to look at the 144 big bore. For what it would cost by the time he sold the 125 and bought the 4 stroke, he would be out $1500. The big bore was $500. $1000 will buy a lot of stuff.

I pulled the motor and sent it to Eric. Ten days later, I had it back. UPS got a little rambunctious in shipping, so we had to order a couple of parts.

I finally got the motor put back in this past weekend. I rode it around the yard and thought the power was noticeably better right off of idle. But the back yard and track are in no way alike. Friday after Thanksgiving we went to the track and - Wow! What a difference! The acceleration out of turns is unbelievable. My son was able to clear a 70' triple out of a turn from the inside with no problem. He tried a few second gear starts and had to work to keep the front wheel on the ground. And I haven't even touched the jetting yet. It's a little fat in the middle, so I'm going to drop the needle. It can only get better! We're also going to go back to stock gearing (currently one up on the rear) so he can hold third a little longer. We lost some over-rev, but that was expected. The next gear will pull with no problem anyway. This thing pulled my 190lbs. around like a 250F. You don't fan the clutch, just flick it. I can't ride 125's worth a flip, but I could ride this one! It was much more than I ever imagined it would be. We went with mid to top porting, but this thing still pulls from the basement. No more excuses!!!

Excellent Work! If you have a 125, this is the best $500.00 you could ever spend. Thank You Eric!

 

[robwbright]

Excellent Work! If you have a 125, this is the best $500.00 you could ever spend. Thank You Eric!

Yep. Worth every penny. Now if I could just ride mine as well as your son seems to be able to. . .

It must be my stock suspension making me slow. ;)

 

[Eric Gorr]

I got a chance to ride my stroked 144 (155 total) last weekend during our Indian Summer. I rode with 2 of my friends who are better riders than me and they have YZ262F and RMZ262s all tricked to the hilt with cams and pipes. I stalked them for a while then passed them on a rough sandy straight.
I love 125s they feel like mountain bikes with engines!

Bruce Clapham brought his new RM125 out and I liked the way handled compared to my YZ. We're going to work on it for Bruce over the winter.

 

[SpDyKen]

Hello Eric,
When I noticed your 155 for sale I was wanting to ask about how well it worked. Thanks for the ride report. What porting specs. of yours did you use and how does the power range compare to stock now. Once I get some time on my new 06 YZ, I'll be sending it to you. I ride mostly woods with fast riders, I don't have any real problem riding a 125 now(03,) but more is always nice, right?
Please keep the great info coming; thanks for all you do here!
Ta Ta for now, Ken W.

 

[robwbright]

I love 125s they feel like mountain bikes with engines!

:nod: Hadn't thought of that, but I like it. :laugh:

 

[dirtracker]

I have an 02 yz 125 w/c I am planning to send it to eric to bore it to 144 this winter season.I dont know exactly what type of porting to choose.Maybe I go mid to top since I dont want to loose much top end , as you have said you have better off idle power and response.I figured it out that your midrange power is incredible with longer over rev.By the way was it set up to run on pump or race gas?

Thank you!!

 

[adam728]

I love 125s they feel like mountain bikes with engines!

That's funny. I just picked up a 125 the other week, and your quote above is exactly how I described it to a downhill mountain biking co-worker.

 

[lwsmithjr]

Maybe I go mid to top since I dont want to loose much top end , as you have said you have better off idle power and response.I figured it out that your midrange power is incredible with longer over rev.By the way was it set up to run on pump or race gas?

If you want to maintain the top end, go with mid to top porting. The overbore gives you more bottom. However, it did lose some over-rev. The bore to stroke ratio is higher than the stock motor so the extreme upper end of the rev range is affected (I'm guessing that's why Eric stroked his). But the pull of the motor is so strong, it is very obvious when you should shift - and when you do, it just starts pulling again.

We decided to stay with pump gas -- Eric said we could see even more gains had we chosen to go race gas, but we did not want to be stuck having to run race gas. If we were attempting to hit all of the big nationals with it, we might have thought differently. But we play as much as we race these days.

 

[dirtracker]

If you want to maintain the top end, go with mid to top porting. The overbore gives you more bottom. However, it did lose some over-rev. The bore to stroke ratio is higher than the stock motor so the extreme upper end of the rev range is affected (I'm guessing that's why Eric stroked his). But the pull of the motor is so strong, it is very obvious when you should shift - and when you do, it just starts pulling again.

We decided to stay with pump gas -- Eric said we could see even more gains had we chosen to go race gas, but we did not want to be stuck having to run race gas. If we were attempting to hit all of the big nationals with it, we might have thought differently. But we play as much as we race these days.

I would rather go mid to top porting and have it set up to run pump fuel.I agree to you that its hard to get stuck on race fuel when its not available.Im not a serious racer I play ride a lot.

I used race gas b 4 but my experience on stock compression motor it didnt make any big difference.I Would prefer pump gas with a spot on jetting.

 

[adam728]

I Would prefer pump gas with a spot on jetting.

That's the problem with pump gas, it's nearly impossible to get spot on jetting without rejetting all the time. Station to station and week to week there is a large amount of variability to pump gas. I run it anyway, I just know I am jetted slightly rich.

 

[MXP1MP]

I love my '06 YZ 144 eric did for me it's sweet go's even faster once I put that 14 tooth front sprocket I beat guys on it this summer at washougal who where on 450's!! You have no idea how awesome it feels to have guys on 450's look at you an freak as your going up horse power hill on that track on what apears to be a 125.

 

[robwbright]

I seem to have gained some top end with mo betta everywhere. Actually, it basically felt the same as my power spread before the overbore - just 20% more of it everywhere.

Eric recommended mo betta to me because I'm a C rider (on a good day). ;)

He seemed to recommend the mid-top for experts.

 

[CagivaWMX]

I did the 155 because I had a stroker crank in the ole storage locker that hadn't sold and thought what the heck, tro it in der!
Mine is set up for low to mid because that where I ride and make the most time. Bruce Clapham described it as a "growler". It revs ok but I'm taking Steve Simpson's advice and adding a V-Force 3 and a FMF Fatty and long silencer. I built an RM155 from an 02 model for my buddy Stevareno, and its a screamer because Steve is a former road racer and mostly ice supermotos it. It takes a while to wind it up but its scarey fast!
I'm riding now indoors at the Waterman International Raceway www.wir.com so I geared it down (12T) and use the PC pipe and shorty. People can test ride it and my KXF262 by appointment. [email protected]

 

[bclapham]

Hey Eric!!! dont get too comfy at the indoor track, it gonna thaw this week so i am hoping to head out to either Fred Bud or doublestuff next sunday, you in???? better bring some octane because with all that cold and sand you know we are gonna hear some chatter!!!:) i think 1 more ride on my 125 before i pull that engine out for the 144.

so here is my take on the bikes, the yz155 is a really nice engine but it was something like ive never ridden before- coming off a essentially stock rm125 that is all topend, the yz155 amazed me in that it never fell off the pipe like mine- infact, since its a 6 speed it can be lugged a bit like a 250 but without the wildness that a 250 gives. of course, it rails the corners like nothing else and flies through the air so you feel like superman. the biggest problem with the yz155 is that Eric has gone from a lazy 450 thumper rider that would run a few laps and curl up in his deckchair and gotten all aggressive and much faster and handed me my ass!!! :)

on my 125, i was actually amazed how fast and engine it is- the first time i rode it was a really long sand track, and with its screaching topend it was easy just to hold it wide open and go fast- infact i was going faster than on my 250 since you cant ride it slow, but 20 mins into the moto its all over since there is no 1/2 throttle solution.

at more tight and twisty tracks and places i am not used to is where i noticed the lack of lowend most- i think i must have cased every jump at walnut that my 250 would have made it over no probem. hopefully eric can set up the new 144 s that it wont loose that sweet topend since the big pile of wornout clutches and pistons in my garage dictates i am never gonna change my riding style!!!

 

[KX250Dad]

As with the original post my son and I have been YZ125-RMZ250F-YZ250 and late season back to the YZ125. The YZ250 holds its own against the 450F's providing your in the right race class so that stays. Refurbished then sold the RMZ, and when racing the 125 given riders of somewhat equal skill they pulled, not pulled away... simply their technology advantage was noted... one of those you pull two bike I'll make up 1 in the turn/jump/in/out things.

So, need a little help here... can I get a 144 "kit" to include all the trimmings, e.g, cylinder, piston, head, etc... for a 2003 YZ125 as once installed I'd send the OEM out?

Should I understand correctly can't race the144 bike in AMA mx amatuer "B" stock (taking a shot at Loretta's this year) although I did see the 144 2stk listed in the stock class. I can however run the 144 in the "B" mod class and I beleve the 250F's in this class are limited to the 250cc?

Do I assume the OEM carb stays and simply tune the jetting?

Can I assume the bottom can handle the additional pwr/trq?

Will the 144 run with the OEM pipe system? If not some recommendations would be helpful.

Given riders of equal skill in outdoor mx would the 144 pull with the 250F's in the higher gear sections (straights)?

In 2007 how much grief from the 250F guys will we get when we show up with a 144 realizing it's AMA legal but racing at outlaw mx... anyone with experience?

Thanks for the help men...

 

[lwsmithjr]

Eric's contact info - [email protected]

The question concerning the "stock" class is a good one. The rule states that the bike must start as a 125 and the increase in displacement can only be achieved by boring -- no stroking allowed. So, it really isn't stock anymore, but the only bike that comes stock as a 144, the KTM 144SX is not legal in this class because it didn't start life as a 125. If it were me, I'd make a call to MX Sports and get them to clarify it for you -- and send you a letter so you will have in writing what they told you.

My carb is the same. It seems a little rich in the middle but I think I can fix that with just the needle.

We are running a a PC pipe w/ shorty silencer and a V-Force 3. It seems to have really good snap off the bottom even though it's ported for mid to top. It would probably have more over-rev if we went with the standard length silencer. That snap off of the bottom really gives it a strong pull out of the turns though.

The 144 will not pull as long as the 250F. In third gear roll-on's, a 250F is virtually equal with a 250T. But the 144 makes it a much more level playing field. If a 250F rider complains about competing with a 144, he ought to go practice more.....

 

[likelite]

right on guys! :cool: 2 strokes will always rule in my world. :nod: i hope they make a come back.the president of ktm said in a cycle newsnterview they will continue to develop 2t's.talked about direct injection that will pass euro 3 emissions. :cool:

 

[hot125mod]

how long do your 144's usually last and what kind of c.p. do you get out of them being a big bore

 

[lwsmithjr]

We only have about 3 hours on our YZ144, so I don't know yet. I think Eric recommends rings @ 15hrs.

 

[burgunder]

lwsmithjr
What jetting are you running. I am waiting to get mine back and need a starting point. And if you don't mind what pipe? Thanks.

 

[lwsmithjr]

The current jetting is exactly the same as it was when we bought the bike. However, I don't know if it's stock or not. We bought used and the bike had a PC pipe and silencer and a V-Force 3. We are at sea level and the bike was perfect when we got it. After Eric did the 144 conversion, it seems a little rich in the middle, but probably just 1 clip position - not enough that I've even messed with it yet. When I pull it apart to move the clip, I'll check what's installed and post here - maybe before the weekend?!

 

[lwsmithjr]

Okay, here is my jetting ---

40 Pilot
420 Main
Needle 3rd Clip position (Was in the 4th)

The bike has a PC pipe, shorty silencer, V Force 3, and Power Now (air box side only). We ride roughly @ sea level and relatively high humidity. Bike is set up for pump gas. Hope this helps!

 

[KX250Dad]

Thanks to all of you on this post, especially lwsmithjr and Mr.Gorr.

After several discussions with Mr.Gorr and lwsmithr I did send my son's YZ125 to Eric and he did in deed have it returned to me as promised as a 144 in time for an AX race. My son raced his first "B" class at the AX and it was actually pretty cool being the only 2T. Prior the race the comments from a few of the 250F piolts were a bit disturbing which is typical of those my stuff is better than your stuff fellows, afterwards the 144 seemed to be a conversation piece (in a good way).

Nope didn't win... didn't even podium, but both rider and bike preformance were what I would consider impressive. Not one 250F pulled away, admittedly the 144 didn't close on the long straight (by AX standards) either. Point was the race was rider skill and the technologies appeared to me to be somewhat equal and that's what I was hoping to see from the 144. All I can say at this time is the 144 appears to have been monies well spent... The outdoor MX should prove interesting and perhaps most importantly my son no longer feels disadvantaged being on a 2 stroke.

Thanks again men........

 

[MXP1MP]

How can you been running stock jetting unless your running a low compression head My '06 YZ 144 I had eric do for me siezed on stock jetting within 40 mins on 114 leaded trick race gas. But I head the high compression head mod's done. I had to go richer up to on the pilot and 4 on the main jet when I got it back.

best mod I did to the bike was put a 14 tooth counter shaft sprocket on it after I got it back. I run 14/48 out doors and so far 14/49 seems to be working really good on the tighter indoor stuff.


I just got a new top end of gorr with the gasket kit and came with that damn moose gasket kit I ran one of those before this last top end and the damn cylinder base gasket leaked after awhile around the edge's the damn material they use is to hard no problems with the cometic or athena's they use a softer more rubberish material that seals better so I have to get another gasket kit.

 

[yz125rider21]

Eric a great guy and service was good, not here to bash but I also had poor packaging...if anything that is one area he needs to take a leap forward at :-)....his work on my bike though is second to none....love it