help with stalling & hard startups!

[moshachusetts]

I recently bought a 07 yfz450 with a motor that was built for mx racing. All I really know about it is that it has a ported head & cp piston. It was built by a very reputable builder so im confident that theres nothing actually wrong with it except its too much motor for me since I only rides xc/woods. Thing goes like a bat out of when wide open but trying to lug it thru the tight trails it stalls a lot & is then hard to get started again, like its loading up with too much gas. Any suggestions as what I can do to tone it down to make it more useable for my type of riding & ,maybe eliminating the stalling & hard start ups?

Thanks in advance for your help

[yfzrider310]

If its a high compression piston I have heard of people putting in a street bike battery in to help get more cranking amps (yamaha r1 or r6 will work). About the stalling you could probably put in a different flywheel and I don't know what kind but like either a lighter one or a heavier one....Man its hard to type with a broken thumb:ermm:

[NickG5755]

smaller front sprocket.. or a bigger rear.. that should help a ton in the woods... what gearing is on it now?

[moshachusetts]

i dont think the gearing is the problem.i think that its built to be ridden wide open and since im trying to lug it around in the woods that its loading open with too much gas , similar to 2 strokes where you always gotta be on the throttle

[Ryan]

Drive it faster then! :eek:




I would rejet it and see what happens.

[moshachusetts]

thats what my buddy says unfortunately i cant. jetting is what i fiqured but whats a good staring point

[Dr89]

jetting is only going to help if its jetted wrong to begin with...so check the plug and if its good then it wont do you any good to mess with it. as far as that goes tho have you checked the plug yet? could easily be gapped wrong or just in need of a new one...

changing the gearing WILL help some...try a 12 in front.

like yfzrider said try a bigger battery, i have an r6 battery in mine with a 12:1 piston and it fires immediately every single time.