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FI MX motor build

2K views 6 replies 3 participants last post by  awheelock67 
#1 ·
Hi,

I´m new to yamahas and I have a couple of questions.

I have yfz450r 2010 fuel injected and I race MX only so I´m looking for mid end top end power


**Camshaft

I have stage 3 cams exhaust and intake, stock 06 cams intake and exhaust and I have 08 cams exhaust and intake. I heard of people using carb cams but are they better than hotcams ?
Should I put the carb cam in the intake or the exhaust ? Anyway whats the difference

***Head
Deck head is worthy?
I head of people going +1 intake and exhaust valves and I heard of people going +1 intake and +2 exhaust? Which set up is better for mx racing
Polish the exhaust?
 
#4 ·
id have mixxer port the head and send your throttle body off to maxbore. larger TB should help top end. Id try just 08 intake cam. exhaust cams are the same, im pretty sure anyway, except timing mark is better on the efi's.
 
#5 ·
X2 on John aka mixxer on here for the head work if you don't wanna break the bank I have his head work on my efi and couldn't be happier. 08 intake cam, bored tb (sredrum), fci, msd or vortex ecu. Although that all said I'd get some good suspension first that'll make you faster before motor mods etc
 
#6 ·
I just bore my throttle body to 44mm but I have seen people go to 45 mm

I´m going to put 08 intake cam and hotcams stage 3 in exhaust and I ´m going +1 valves overall .

I called john at racers edge and he told me that going bigger than stock in the thottle doesn´t work
 
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