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Year 2008
Make CRF450R

Sea level riding, Mostly sand tracks, Temp between 59-80
No modifications all standard as per owners manual for New Zealand.
Current jetting, Main #178, Pilot #42, Pilot screw 1 1/2 turns, needle nkat , Leak jet#55
Starts fine. When running at steady throttle the bike surges/pops. Does not matter if it’s at 1/4 to ¾ throttle still surges/ pops. Accelerates fine if you open the throttle to full. No change from hot to cold motor. This bike has only had 8hours on it from new and ran fine until stored. Got it from a friend he rode it twice then it sat in his garage for the last 3 years.
Had the carb off cleaned it all looked like brand new
New fuel
Checked fuel filter in tank, all ok
Checked valves, all ok
Checked air cleaner, like new
Checked exhaust, all bolts tight no leaks
Took bike to bike shop they dropped the needle from the third clip slot (Third is recommended setting from new) to highest clip first (leanest) this did fix the problem. My problem is that I think it needs a different jet/needle set up or am I get thinking too much into it?

A wrong stator give on my 2005 the same result, find a specialized shop like RM stator and ship it to them for inspection.

If the bike ever run great with this jetting (in the same condition) stop focusing on it, the trouble should be otherwhere

You are running it way too rich. Stock main jet is way rich. Try putting the clip back on 3rd groove, 165 or 168 main jet, 45 pilot. The best thing you could do is find a local dyno shop, with a Wide Band Sniffer, and they can get the AF(air fuel) ratio set perfect for your area. BTW I'm running my 08 450R at 5280' elevation, 42 pilot, 160 main, clip on 2nd position, runs perfect. When it gets real hot I put in a 158 main, 42 pilot.

if ya bikes been sittin bro it is a fuel prob blocked jet(s) perished diapham talk to ken he will sort ya out

My problem is that I think it needs a different jet/needle set up or am I get thinking too much into it?

The 08 R except for very high altitudes.very cold temps is jetted great from the factory. Bikes that were jetted fine, had no modifications, running in the same climate, etc. don't just suddenly need jetted .

You are running it way too rich. Stock main jet is way rich.

Nope, the stock jetting on an 08R is good for most anywhere...except Colorado New Zealand unless very high in th emountains is hardly Colorado.
The sitting 3 years is the problem here. At a minimum the pilot jet needs thoroughly cleaned.
My recommendation is clean the whole carb,all jets,all circuits, and with compressed air too.Then restore the stock settings.
Make sure the fuel tank is spotless too.
Stabil is cheap and will keep this from happening again. Any storeage longer than a couple weeks should be done with Stabil in the fuel tank and having been run through the engine a few minutes. Then shut it down, drain the float bowl and you won't have this problem ever happen to you. Doug

[email protected] wrote:

My problem is that I think it needs a different jet/needle set up or am I get thinking too much into it?

The 08 R except for very high altitudes.very cold temps is jetted great from the factory. Bikes that were jetted fine, had no modifications, running in the same climate, etc. don't just suddenly need jetted .

You are running it way too rich. Stock main jet is way rich.

Nope, the stock jetting on an 08R is good for most anywhere...except Colorado New Zealand unless very high in th emountains is hardly Colorado.

"Good" is not optimal. If you noticed I didn't suggest he run "mile high" Colorado jetting of 158 main, I suggest 168 which is way too rich at my alt. as verified by the wide band sniffer. I was using 168, and it seemed to run very well, when I originally dyno'd. Sniffer showed it way rich, dropped it to 158 and gained 2 hp.