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Yes, this is often the case Leo Vince. It's more a matter of them not requiring jetting, vs others that may require jetting to run well.
 

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For the DRZ, the header is the biggest restricition in the exhaust system, so unless you change that to a better flowing header, there's no additional flow to compensate for by adjusting the jetting. In other words, a slip-on for a DRZ does nothing but make the bike sound different. You're further ahead to save up a little more money and go for a full system.
 

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but for the time being if you cant afford a full system why not buy the slip on for some good looks and start saving for the right jet kit and a good head pipe. most people cant afford everything right away so thats what i plan on doing. get the powercore4 now and then mate up a nice head pipe when the money starts flowing again.
 

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but for the time being if you cant afford a full system why not buy the slip on for some good looks and start saving for the right jet kit and a good head pipe. most people cant afford everything right away so thats what i plan on doing. get the powercore4 now and then mate up a nice head pipe when the money starts flowing again.

yeah - that is a good idea for sure - might go the same route myself
 

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Keep in mind some headers (and full systems) have head pipes no larger than an E header. For example, all FMF DRZ specific head pipes are identical in size to an E header. While better than an S/SM header, they are still not optimum. Do your homework before purchasing. Most slip-on's are close to 3 bills. You can get a full Yoshimura exhaust system for around $450. You'll have more than that invested by the time you purchase your slip-on, head pipe, and midpipe (if needed). I maintain it's best to save for awhile longer and live w/ the stock exhaust system until you can purchase a dedicated full exhaust system.

The right jet kit for the Mikuni carb. is the James Dean jet kit (part #JDS005). Excellent product, w/ much less complaints compared to the Dynojet (and all the rebadged Dynojet kits~Moose, FMF, etc). It seems 90+% of those w/ Dynojet kits installed complain about surging/hunting at steady throttle cruising.
 

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Keep in mind some headers (and full systems) have head pipes no larger than an E header. For example, all FMF DRZ specific head pipes are identical in size to an E header. While better than an S/SM header, they are still not optimum. Do your homework before purchasing. Most slip-on's are close to 3 bills. You can get a full Yoshimura exhaust system for around $450. You'll have more than that invested by the time you purchase your slip-on, head pipe, and midpipe (if needed). I maintain it's best to save for awhile longer and live w/ the stock exhaust system until you can purchase a dedicated full exhaust system.

The right jet kit for the Mikuni carb. is the James Dean jet kit (part #JDS005). Excellent product, w/ much less complaints compared to the Dynojet (and all the rebadged Dynojet kits~Moose, FMF, etc). It seems 90+% of those w/ Dynojet kits installed complain about surging/hunting at steady throttle cruising.
I wasn't aware of the head-pipe cost - good points - I was saving for the performance mods this winter anyway - Think I'll stick with that plan and probably do the Yosh RS-2, airbox, and j-kit altogether.
 

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Discussion Starter · #9 ·
so i do not have to rejet if a slip on is my only mod???????

i am convincing myself more and more for the JD kit with 3x3 and K/N just sucks i am between jobs right now and not extra cash laying around.....i like the look of the big thumper mufflers i know some dont but i do and the leo vince looks bad ass i think...

a local shop has a leo vince on hand they will gimme 15 percent off on since its a display model.

i just wanna make sure i can stick it right on with stock jetting(no other mods except i let out the pilot screw about 1/8 turn.
 

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No need to rejet w a slip-on, and I can't see any reason why you would have to fool w/ the pilot circuit. The mixture screw is sealed anyway, so you'd have to remove the carb to drill out the cover and access the screw. If you do the 3x3, you need to rejet. Otherwise, don't tinker w/ the jetting.

3x3 = additional airflow, requiring more fuel flow to compensate, so larger jets are needed.

Slip-on = No additional exhaust flow due to restrictive headpipe, so no need for larger jets.

Make sense?
 

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I installed fmf full exhaust,air box vents and JD jet kit what a differences over stock. Much more low to mid power no problems at all with this upgrade nice package. Sounds like a 450 dirtbike if looking for that brrraaapppp.
 

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Discussion Starter · #12 ·
so let me get this straight, any slip on to the stock header requires NO jetting????


the previous owner said that he drilled out the plug and let out the pilot screw 1/8 of a turn and it runs a tad cleaner...maybe since it was a tad lean from the factory?
 

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Yes, they are a tad lean from Suzuki to meet EPA emission standards. No, a slip-on provides no additional flow because the header is still restrictive, so there is nothing to compensate for by rejetting. Even if the slip-on muffler is less restrictive than the stock muffler, w/ the stock header in place it makes no difference. You must rejet when you do the 3x3 because it does provide additional airflow into the intake tract.
 

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x2 on that!! after wanting to get better sound for a long time and then reading pages and pages on tt there is no other way than save up and buy the whole thing. but im impatient so i buy things in pieces and work on a full house.
 

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I installed fmf full exhaust,air box vents and JD jet kit what a differences over stock. Much more low to mid power no problems at all with this upgrade nice package. Sounds like a 450 dirtbike if looking for that brrraaapppp.

I'd like to see those "air box vents" by the way.
 

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Discussion Starter · #16 ·
ok so if i do a straight through slip on like a yoshi, hmf, or muzzy i do not need a rejet or other carb mods? i thought with a straight through muffler it will run to lean......
 

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the drz comes from the factory already lean for smog so if that is the case then it wouldnt do anything to the stock carb. sound and weight savings i believe is the only thing you'll get out of a slip on, which works for me.
 

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Discussion Starter · #18 ·
sound and weight is what i am after, i will rejet and 3x3 much later down the road, right now i just want a slip on but have a hard time beliving no jetting is required for just the slip on, even my DR needed a rejet after a slip on only.......doesnt sound right.......
 

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The slip on might be a little less restrictive (than stock) hence the noise Db note, but not enough for re-jetting. Again, it's the stock midpipe that is the "restrictive" culprit. I've yet to come across a slip-on for any bike (unless it had NO baffle at all) that required re-jetting. Even then, it might not be warranted. Just the way it is......
 

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Discussion Starter · #20 ·
well these pipes like the HMF, muzzy, and some yoshi's are straight through with no baffle, just preforated holes with fiberglass packing.

should i look for a more restrictive non straight through slip on like a FMF?

powercore4 maybe? how many of you use slip ons with stock jetting???

right now i removed the spark arrestor and enlarged the exhaust tip, and it improved sound alot but i am wanting more sound now.
 
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