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Hi!
My name is Chris and a have a Crf450r 2006 engine (in a 2012 frame)

Having some troubles to find the correct jetting. If anyone can give some advice will by great.
So, my bike parts is the follows

Fcr 41 (2006)
Hotrods crank with rod 617
Cylinder works cylinder (stock 96mm)
Cp piston 96mm for 13.5 CR
Stock head ( only some polished )
Stock gaskets
Stock cam (2005)
Stock exhausts valve set (new)
Steel intake valves with dual springs
FMF power Bomb header
Leo vince X3 dual mufflers modified to 45mm each.

Carb jetting.
(Im on sea level, 30C, supermoto use)
Pilot 48
Needle stock honda at 5th clip
Main 195
Screw at 1 3/4
Pump diagraf -2.5mm
No Oring mod.
Leak 50
Bowl level 9mm

The bike starts at first kick hot or cold without chock. I dont have backfire (if i lower the ar screw i have a lot of bf) but i have some blogs or pops to middle rpm and sometimes the idle stalling a little.

Thanx for your help.

45 pilot, just like the other CRF's, fuel screw 1 7/8 out, main jet 162.

Higher compression engines are more efficient, and since an engine is an air pump, it can pull more fuel through any given jet.

Thnx for the answer. Im gonna try this jetting in few hours and post the results.

I forgot to say, my bike run a little warm. I check timing, water pump and radiators plus hoses but all is good. And, if i turn the fuel screw lower than 2 turns i have bf. My max rpm is to 1 turn (with hot engine) but i have bf to much and the engine turns to cut down like "no fuel" or "thrash in pilot jet". I have install new oem connection on carb and new gasket on exhaust. No leaks. Double triple check. The carb is very clear inside, jets to. Valves are sets as manual , and no engine strange noises or something.

Ok, with this jetting.
Idle stable no heat
mid not prefect but no heat
Hi revs - full open throttle, over heating. Cap in radiator is 1.6 bar. Im gonna check the plug maybe i raise the main 5

Is it overheating while riding? All 450's overheat idling on the stand.

Is it overheating while riding? All 450's overheat idling on the stand.

Yes, while riding. I put a 180 main and the spark plug looking very good plus the overheating in f.o.t. stopped. Maybe i must change the needle 1 clip up. I open the right side of engine ang the water pump cover to ensure for leaks. All good. Maybe the opened boot of 2012 and the twin air filter acts deference from 2006 to the mix. I check the spark plug tonight again. But with 45 pilot and 2 turns, the idle are stable now with no b.f. thnx a lot.
One more, i have all the stock jetting of 2002-2008 X and R models 250 and 450. If anything gonna help anyone just show my the way

Problem solved. Leak from head gasket to cooling system. Deck ok new gasket and all perfect. 160 main 4th clip the needle and 45 pilot.
New problem. After this i install stage 3 hot cam. Cp is now 13.8. The problem is, when i put out air filter is running good except 1/4 1/2 but when filter is up.. is a very slow bike... I drop the main to 155 with out air filter and gain power. Im gonna raise the pilot to 48 to see the bottom end power (i dont waiting to see a lot of power cause the cam is for mid and high power. Just an easier starts, now needs 2 3 4 kicks). After i see the plug to 1/2 and to WOT to solve it. I post the results after for database.

Finally! For the records....

Pilot 48
Mixture screw 1 3/4
Main 150
Needle clip 5 (from top)

Running like the hell... starting with first kick and no bogs or back fire

Thanks for the feedback I am sure it will help others

It is starting first kick because your pilot is too rich. It will run, but a 45 is better.

Nop, spark plug is colored as ngk manual. Forgot to say i replace the oem air filter with KN free air filter. If im going to 45, getting hot, dont start if i dont pull the throttle one time, and i have back fire. I test 2 weeks the bike. 48 and 1 2/4 - 3/4 its top. I change the screw to a new one, and nothing.