Two Stroke Motocross
Two Stroke Motocross Forum => General Two Stroke Talk => Topic started by: MOMSMX47 on November 30, 2012, 04:22:30 PM
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After four years away from the sport I am finally getting back into racing. I spent two years on a four stroke and hated it with a passion, the whole valve thing took the fun away from things for me, I really missed my "roots" of just going out and having fun and ripping it on my two stroke so I went through and put through a deal for a 2013 YZ 250 should be in just a matter of days at this point i'm told, already have all the parts waiting for her . The list below is what I've put into it. Planning on having my co-workers here at the shop put in a port job on it as well as having the suspension revalved to my specs. Other than that, what other suggestions do you guys have for this thing. I've ridden Red my entire life and this is my first time EVER riding blue so any help is appreciated.
FMF Fatty
Powercore 2 shorty silencer
Pro Taper Contour Reed bend bars
Pro Taper Aluminum Throttle tube
Fork bleeders
Works conn. Rad. braces
Factory Effex gripper seat cover
Cycra Speed skid plate
ARC Unbreakable levers
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Add Vforce or boyesen reeds to the list as well. Cleaning up the porting wouldn't be a bad thing either.
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good on ya moms!
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was thinking of the boyesen reeds but I never was able to figure out what kind of power gain you got out of these
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1-3 hp through out the rpm range. They work great. Cleaning up the porting would make it even better.
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I have someone at my work that does porting he is excited to get into it and see what he can do , have you done port jobs on the YZ before and if so do you have advice what to do or stay away from as far as porting?
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No, I will be having mine cleaned up though after this winter. Cleaning the casting flaws will create better flow there for more power. There are people on here with experience with porting that should be able to chip in with more info.
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Might I suggest that you also get some head mods done for a little more compression while you've got your motor at a mechanic? Compression = power. It seems that you're concentrating your mods to get more low to mid power. Good call, 250s are monsters bone stock, adding overrev is crazy if you ask me. My 01 YZ250 being revved, with bald ass tires, stock expansion chamber and no engine mods that I'm aware of is... unsettling. Fun, if only because your blood just got six litres of adrenaline pumped through it
. Mid range power is also alot more tractable and controllable which is a huge advantage in terms of fatigue and traction.
Looking forward to some pics mate.
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BINGO!!! I had a few people that wanted me to add all kinds of stuff that will give it all kinds of top end speed, at the end of the day that would NEVER be useable power for me because the tracks around here combined with my riding ability/style never allow for that. At the end of the day I want a bike that is going to have max potential in all the areas I'm actually going to see the difference in.
I was suggested to think of a flywheel weight for it btw, thoughts?
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As flat and straight as tracks are today that over rev will save you on the straights. You could try a 36mm PWK, people are doing to their 02 up cr250's with great success for low end pull with out losing top end. As for porting, what I suggested would simply improve power all over, not drag port status. Head mod on this year is also crucial in that yamaha lowered compression in 2011.
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Great! Keep the advice coming, I will be talking to someone this week on what we can do to the head, first and foremost I want to ride it with the mods I have on it now and get comfortable on it and analyze what it needs. This will be the first time I have resources available to me to make changes on the fly like that so I'm certainly going to take advantage of it if I can
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As flat and straight as tracks are today that over rev will save you on the straights. You could try a 36mm PWK, people are doing to their 02 up cr250's with great success for low end pull with out losing top end.
This is a fair point. Where you should focus your power is greatly influenced by your track(s). I'll leave the decision up to you but you should still be able to pull the 250Fs on all straights even if it signs off at 9 grand. Its not like the YZ125 that pulls and pulls and pulls till redline.
With regards to the flywheel weight, it really depends on the track. I wouldn't want to slow down my bikes revs in the slightest unless the track demanded it. Hard packed dirt is where a flywheel weight will be worth its weight in gold. But when the dirt gets softer you'll be wishing it would disappear.
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i have to agree with stusmoke, having tested a fly wheel from hard pack and loam to sand it only feels right on the hard stuff.
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A flwheel weight does not loose you power anywhere in the rev range. That includes top end.
All it does is slow down the "Hit" when you get in the powerband.
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A flwheel weight does not loose you power anywhere in the rev range. That includes top end.
All it does is slow down the "Hit" when you get in the powerband.
I know, I wasn't saying that it did. I didn't meant to anyway.
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Well seeing how Southwick is my playpen out here in MA I'm guessing that it wouldnt be the best idea then
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Hehehe no probably not. The hit of a two stroke allows it to get on top of the soft stuff quicker and stay there. A huge advantage over the four jokes that sink like the titanic in it.
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I wonder why if thats the case no pro has run a two stroke out there in a while....wasnt a dude trying the SX series on a smoker a few years back?
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Unless you are an Expert or Pro rider, I would really concentrate on suspension and handling before major motor work. Pipe, silencer, light porting, and VForce reeds should be all you would ever need, head work might require race gas, big $$$!. I'm an old NESC racer from the '80's, Southwick was always my favorite track. But at my best I was a top C rider, even got my picture in Buckley's Motosport magazine a few times. At that, my lap times at Wick were always faster on my 125's than my 250's. More HP does not always turn into lower lap times, but better suspension always does.
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Thanks Russ! I am for the first time putting big money into my suspension this time around. Having C-cycle turn their magic on revalves for both front and rear for me and im going to stay up to date and on top of my suspension, something I neglected when I was on my 250F and 125. I think this will have a significant difference in my results this time around.