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07 crf450 supermoto 498 big bore jetting suggestions

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Hi, I have a 2007 crf450 that is in supermoto trim and I'm looking for some suggestions on the jetting for an engine i just got done building.

Here's the list of the engine mods, carb specs and riding conditions.

07 crf450

engine mods

Hotcam stage 3 shimmed to .004 intake and .008 exhaust

ported head with stock size TI valves

Ice cube 498cc big bore

12.5.1 comp ratio

k&n filter with air box sides removed

full PC exhaust

vertex 10 position cdi

falicon crank

CARB

stock bore fcr41mm but im looking to get it taper bored to 43.5mm (suggestions on this)?

crfsonly fuel screw 1-3/4 out

main jet-178

pilot-42

needle- NJYR

clip- 3rd

leak jet-50

Riding conditions

altitude- 1800-4000

temp 60-90f

fuel-93 pump

supermoto style riding mostly street with track occasionally

Any suggestions on a good jetting baseline would be greatly appreciated!!

thanks,

Matthew

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Big bore jetting is often leaner than standard bore. You should have been at a 162 main for 2,000 feet and above. You are drowning it in fuel right now. start with a 165 for the colder temps and see how it runs.

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ok I orderd a 165 main from the stealership and it will be here in the morning. Is the NJYR needle a good needle to stick with and should i just leave it on the 3rd clip?

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OK I put the 165 in and got the fuel screw 2 turns out and it runs like crap up top. Pulls good till around 7 or 8k rpm's and then it falls on its face, put the 178 back in and it fixed the top end but it doesn't sound as (crisp). Any ideas why it wants a fat main jet?

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