Motor mods for MX

[moto50]

My yfz is stock and extremely reliable and I have a Wr crank and a 13:1 Wiseco piston to put in it and some people are telling me not to put the high compression piston it it because it won't be reliable any more.
Has anybody been running a Wr crank with a 13:1 Wiseco piston? is it reliable? I was also going to do the cam mod while I did the crank and piston. does anybody have any other suggestions. I have aslo heard a dyna ignition works great.

[red33quad]

Put your money in suspension. You dont need any motor work to race on a yfz unless your racing at a Pro level. Put a pipe on and jet it right and practice. Its all about the rider. You start working on the motor and thats all you'll be doing , Working on it !!
Good Luck !!

[EvilJester400EX]

13:1 and a WR crank is a bad idea, all of my friends who have done that have been blowind head gaskets left and right. I'd recommend 12:5:1 with the WR crank. The dyna ignition is good, but I run the GYTR and have had no problems with it, also dont' have to drop 300 bucks for it.

[atva_63]

when I got mine built I was told when you bore them to the true 450 is where you will begin to have issues mine is at stock bore with 13.5:1 JE piston. As far as your crank I have no Idea

[EvilJester400EX]

You won't begin to have problems by boring it to a 450, however, boring it to a 470 will make it an unreliable 4 wheeler for motocross riding.

[atva_63]

Originally posted by EvilJester400EX
You won't begin to have problems by boring it to a 450, however, boring it to a 470 will make it an unreliable 4 wheeler for motocross riding.

I am not saying you are wrong, or judging your knowlege but. What you said is true. With my experiences with puting mods on a motor for mx anything you do change thes reliability that you have over a stock motor. with the compresion I have and the factory crank, boreing it would of made it less reliable than what it aready is.

p.s a person deose'nt need a 470 for mx if they know how to ride it

[Warnerade]

Originally posted by atva_63
p.s a person deose'nt need a 470 for mx if they know how to ride it what do you think kory ellis has?

[EvilJester400EX]

ATVA, I agree with you- when you bore a YFZ engine you run into overheating issues because of how close the cooling jackets are to the head of the engine. The stroker crank is the better way to go anyways, more power all around.

[MXRACER86]

Originally posted by NacsRacer027
what do you think kory ellis has?
A 450!

[daddio]

Originally posted by MXRACER86
A 450!

but is it stroked or bored to 450?

[moto50]

Stroked
http://www.albaaction.com/motors/pages/YFZmotor1.htm

[muff]

its funny reading some of these posts on here...

anyways since you have the wr crank sitting there I would definetly recommend running that. however I would go with the stock yz piston instead. I ran the wr/wiseco in mine for around a month or so, until I saw 2 other wisecos blow, the first came with an improper oil ring cap, and the wrist pin failed in the second. (both for the yz) I decided to throw the yz piston in and have been running that since. (No headgasket problems with either)

I would say the wiseco ran with a little more grunt and you were able to lug it a little better, but with the stock yz it revs right up with plenty of power

As for ignition, I'm still running my stocker. I have a GYTR sittin here but havent gotten around to tryin it out yet. Your best bet would be to put the wr setup in, run it, and go from there. but I think you would be better off adding a few suspension modifications before messing anymore with hp

[moto50]

I have long travel Burgard a arms and long travel Elka's.
My motor has been really reliable stock and I just heard about some guys blowing head gaskets with the high compression piston. I have heard there are oiling issues with the stock pistons too.

[atva_63]

[QUOTE]Originally posted by muff
[B]its funny reading some of these posts on here...

anyways since you have the wr crank sitting there I would definetly recommend running that. however I would go with the stock yz piston instead. I ran the wr/wiseco in mine for around a month or so, until I saw 2 other wisecos blow, the first came with an improper oil ring cap, and the wrist pin failed in the second. (both for the yz) I decided to throw the yz piston in and have been running that since. (No headgasket problems with either)

it is possible that your wrist pin failed due to the oiling issues
You can get this fixed for about $50 and 2-3 weeks turn around, with you breaking down the motor. I would recomend this if you are tearing it down anyway.

moto50 since I am out you can aford to loose a few points and give your bro a chance to win:D :D :D