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how can i tell if its jetted?

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so i got a 400sm a while ago.. the guy said it had the full yosh exhaust, 3x3, and rejet.

obviously i can see it has the full exhaust, i popped the seat and saw the 3x3 hole cut..but is there a way.. without taking the carb off to tell if its actuall been rejetted?

im not very mechanically inclined, but i want to learn.. part of me kind of hopes its not, so i can take it all apart and do it.

anyways, thx for any tips.

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runs fine, at least as far as i can tell... its my first drz so i dont have anything to compare it too. backfires a bit on deceleration.

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decel pop is normal for a bike with full pipe.

you have to take the carb out and check your jets to see..my guess is that if the PO took the time and money to buy a full pipe and do 3x3 then they must have re jetted the bike. but pull the carb and look at pilot and main jets and look for a tampered fuel screw

edit: un the bottom of the carb the fuel screw came from the factory with a brass plug hiding the screw. if its not there that would ba a good indication that the carb was jetted

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decel pop is normal for a bike with full pipe.

you have to take the carb out and check your jets to see..my guess is that if the PO took the time and money to buy a full pipe and do 3x3 then they must have re jetted the bike. but pull the carb and look at pilot and main jets and look for a tampered fuel screw

edit: un the bottom of the carb the fuel screw came from the factory with a brass plug hiding the screw. if its not there that would ba a good indication that the carb was jetted

What he said ^^^^^ It sucks but at least you will have peace of mind what the jetting is.

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check the screws on the bottom..if they have been changed to allen heads then most likely has been re jetted

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it looks like this

Yk6XQ.jpg

well as said above usually the float bowl screws get swapped out when jetted as the stock screws are butter soft. they look like they have never been touched but i could be wrong, so its best to check. plus the drain screw looks like its un molested as well,

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After doing the 3x3 mod my bike would not run correctly at all. If it runs like a japanese bike should, It has been rejetted.

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so i got a 400sm a while ago.. the guy said it had the full yosh exhaust, 3x3, and rejet.

obviously i can see it has the full exhaust, i popped the seat and saw the 3x3 hole cut..but is there a way.. without taking the carb off to tell if its actuall been rejetted?

im not very mechanically inclined, but i want to learn.. part of me kind of hopes its not, so i can take it all apart and do it.

anyways, thx for any tips.

Remove seat and tank, you can get a screwdriver to the top screws and remove carb cap, spring and slide will come out with a bit of work.. remove needle cap (pull straight up.. no rocking motion or you will break the plastic fingers that hold the needle cap in place) if the needle is adjustable (has different clip positions) you have a jet kit, as the OEM needle is not adjustable...

All that said..

If it is running well, forget about it and ride.

If it's not running well, you’re going to need to know what size jets are in it, as well as needle position and flue screw setting..and all that means the carb comes out.

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Remove seat and tank, you can get a screwdriver to the top screws and remove carb cap, spring and slide will come out with a bit of work.. remove needle cap (pull straight up.. no rocking motion or you will break the plastic fingers that hold the needle cap in place) if the needle is adjustable (has different clip positions) you have a jet kit, as the OEM needle is not adjustable...

All that said..

If it is running well, forget about it and ride.

If it's not running well, you’re going to need to know what size jets are in it, as well as needle position and flue screw setting..and all that means the carb comes out.

Yeah..that's the easiest way to tell....As Eric said, If it is running well, forget about it and ride. ..:smashpc:

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ok thx a lot guys, ill keep on riding!

just did my first oil/filter change on it. and for the hell of it a coolant change. i like piece of mind knowing when it was last done and the right stuff is in there.

i think todays project will be adjusting the throttle freeplay. and figuring out why my clutch lever isnt fully releasing when i let go... i think its just getting caught up in that rubber boot...maybe the cable needs to by lubed.

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