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two drz400sm's close to stock with noticable performance differences?

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Hi all,

I recently purchased two 2007 drzsms for my son and I. There is quite a bit of difference in performance between the two and I can't figure out why. Bike #1 is totaly stock except for a carbon fiber two brothers exhaust. Bike #2 is stock except for the 3x3 airbox mod and re-jetting. While both bike run good bike #1 has much better top end easily doing 70 in 5th gear without winding it out at all. Bike #2 with the airbox mod is past a good rpm range at 70? Both bikes have identical stock sproket setup, same tires, everything is the same except the pipe and airbox mod. I would expect the bike with the airbox mod and rejetting (also has k & n airfilter other bike has stock) to get better performance top end wise? Could the pipe make that much difference?

Tad Fitzgerald :ride:

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Both bikes were adult owned and according to the sellars broken in properly. Waiting to hear back from one sellar on the jetting with the bike that has the 3x3 mod. I will post when I hear back from him. Thanks for the feedback.

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Before I take the carb off and ckeck myself I'm waiting to hear back from the sellar, he said he had it it jetted for sea-level to 4000 ft specificaly for the 3 x3 mod. If the jetting was wrong I would have expected the bike to sputter or cut out which it dosent do, just the top end speed. I will post the exact jetting when I get it.

Tad

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When you say "winding it out" it sounds like you're referring to a difference in gearing. But if you're suggesting the 3x3 bike has less power at higher rpm, it may be jetted incorrectly. The only way to confirm this is to take the carb off and tell us what you see inside. I would suggest doing this as it's not only a piece of mind but you can probably get the bike to run much better.

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i will take "the jetting is wrong" for a $1000 alex.

The previous owner might have been cheap and tried running a 150 main w/ stock needle. Had a buddy running this and the top end was garbage. Speculation does not beat confirmation, though.

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The previous owner is my no means cheap and he's a stand up guy. I think what may have happened is when he returned the bike back to stock whoever did his jetting for the oridginal stock carb may have jetted it wrong. He had the fcr and full yoshi setup that he removed prior to selling it. So the stock carb needed to be jetted correctly for the 3 x3 mod. It's not running poor enough for me to remove the carb at this point since I'm going to put on an fcr and yoshi pipe anyway. Eddie correct me if Im wrong but it should be running a 155 main, stock pilot jet, and needle clip on 3rd position.

Tad

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The stock carb can stay in the boots on the bike to get to the slide and bowl. Just loosen up whats necessary and rotate as needed.

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are you saying that the rpms on one bike is higher than the other at the same speed in the same gear? cuz that's not likely at all unless someone changed sprockets or gears.

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Jetting is 142.5 main jet

25 pilot jet

2.5 turns out on fuel screw

Like every one has said, 142.5 mine is stock.

Stock pilot is 22.5

If your needle has clips as you indicated in one of your post then it is not stock. Does your needle have a red or blue color on the top of the needle?

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Thanks much for all the feedback. Looks like I need to re-jet it. Anyone know the best jet kit to use. I have the 3x3 mod, k&N filter, stock pipe. I'm assuming there will be directions in the kit in regards to elevation? I do the majority of riding at 2000-4000', occasionaly higher. Still thinking about just ordering an fcr carb from Eddie allready done and adding the mrd pipe. If I can't afford to to it all now what would best, get the pipe first and re-jet or get the carb and leave the stock pipe?

Tad

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