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Should I rejet my FCR?

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I have done some searching and I can't find what I am looking for..so here I am.

I recently installed a TT FCR 39 on my 08 Suzuki DRZ-SM. I followed the install instructions to a t and the bike is running much better but it still feels a little flat performance wise. It is also requiring a bit more throttle input when climbing even small incline on the highway to maintain a steady speed.

Riding/Jetting conditions are as follows:

600ft elevation,aftermarket pipe with open muffler, and e base gasket -

160 main jet

200 main air jet

EMN needle

clip 3

45 pilot jet

removed pilot air jet

EFS 2.25 turns out

Merge Racing AP spring

I have adjusted the AP timing so there is no bog at all. The bike idles fine however I have noticed a slight RPM hang when rolling to a stop. The idle might hang for 3-4 seconds at a slightly elevated RPM before settling into the 1500-1700 range. I am getting a machine gun pop on decel in the higher RPMs and there is the flat response in the mid to upper range. I pulled the air cover door and that resulted in plenty of power to lift the front tire in second without the clutch and the upper range has more perceived power. I say that only because I don't have access to a dyno or any other real way to test at this time. However, the butt-dyno does sense a positive difference.

Would it be advantageous to rejet to maybe a 158 main jet or to mod the airbox cover to allow more air in?


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Two different issues.

A 45 pilot at 2.5 turns on the FS should be fine, as well as the EMN needle. I suggest double checking the needle and confirm you did not have the EMR in by accident.

Based on your airbox door test, and assuming your 3X3 is truly 3" X 3", you main is rich. I'd put a 155 in and redo the test with the door off and again with 1/3 of the the 3X3 taped closed (seperate tests, of course) to confirm.

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Thanks, I will retry the door test after dropping to a 155 main. I checked the needle and I indeed have the EMN installed on the 3rd clip. I also have the airbox modded with at least a 3X3 hole, it is more like 3.75X3.25.

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