Should I rejet my FCR?

I have done some searching and I can't find what I am looking 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?


It sounds like you solved your own problem, do the 3X3 on the airbox and see how she runs. good luck!

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.

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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