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What Jetting For My Mods?


J-Madd

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Just thought I'd let ya'll know. I think the slides ARE in the wrong carbs. I put them back in the same way they came out. I think they were in wrong since I bought it. The cut away portion of the slides were towards the cylinders, not towards the airbox. Isn't that the opposite of what it should be? I'll put in my 240s and fix the slides and let ya know.

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It runs great now.

 

I raised the needle clip position, put in 240 mains, air screws 1.5 turns out. It screams through every gear. EXCEPT now its too lean at all throttle ranges. I think I could even go bigger on the mains. I haven't done a plug chop, but it sounds and feels lean at WOT. It is also lean at idle to 1/4, and 1/4 to 3/4. Running MC1 @ 40:1 and no smoke coming out of the pipes once the motor gets warm. It definitely does NOT sputter at any part of the throttle.

 

What do ya'll think about going to 27.5 on the pilots, 250 on the mains, and moving the needle clip back down a notch?

 

(Reminder: my only mods are K&N, airbox with holes in lid and snorkel removed, Boyesen Power Valves and Pro Series Reeds.)

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Try raising the needles back up to the 3rd clip then....right now your at the 2nd clip from the blunt end right? Go back to the middle clip, stay w/ stock pilots...Do a plug check after running it wide open throttle in 6th gear for 5-10 seconds. pull over and check the plugs....white or tan is lean, brown is perfect, black is rich....might want to adjust air screws for throttle response....remember, the stock pipes don't pull very well on top end, so you can't expect much there... another set of pipes will REALLY wake it up on top and bottom w/ the right pipes..

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Try raising the needles back up to the 3rd clip then....right now your at the 2nd clip from the blunt end right? Go back to the middle clip, stay w/ stock pilots...Do a plug check after running it wide open throttle in 6th gear for 5-10 seconds. pull over and check the plugs....white or tan is lean, brown is perfect, black is rich....might want to adjust air screws for throttle response....remember, the stock pipes don't pull very well on top end, so you can't expect much there... another set of pipes will REALLY wake it up on top and bottom w/ the right pipes..

Yah' get some pipes dude. It's like the wake up call of wake up call's. Your shee is sleeping right now and you need to hit in the head with some Toomey's or CPI's or somethin'. I just did that and it's like Dr. David Banner turning into the freaking Hulk, Jeckle into Hyde, you get the idea. Best thing you can do, man!! If money is the issue go to ebay and get some FMF's. You can get a good deal on them there, used, whatever.

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I can't thank everyone enough for the help.

 

I plan to get pipes ASAP, get it jetted, then put in my new Wisecos, I want to get the jetting dialed in on the old pistons, before I put the new ones in. I ride trails and climb some hills, but I LOVE top-end and acceleration. What pipes should I get? I know Toomeys are killer on top end, but I heard that they lack a little on bottom. The way I ride, I like to "keep it on the pipe" anyway. Wouldn't T5s or T6s be ok if I keep it at high revs most of the time anyway?

 

By the way, the needle clip is now on the 2nd notch from the blunt end. I'm gonna put it back to the 3rd pos. I'll do a plug check when I get a chance, and dial in my mains.

 

Thanks again

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Just about any pipe out there will give you way more top end power and speed over stock...the stock are that bad....for your type of riding, I'd get either Ptr mids, fmf sst's, dmc, bills, in that order from most midrange and low end to midrange...you wouldn't regret any of them and would gain top end as well as more low end and midrange...the top end pipes are only better for long running areas, you won't gain anything in trails over midrange pipes....

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Never mind about the pipes.........I just bought some T5s on ebay.

I need to know where to start with jets.

 

Current Air/Fuel settings: air screw 1.5 turns out. #25 pilots, 240 mains, needle clip (soon to be) at 3rd position.

 

Mods: K&N, holes drilled in airbox lid, Boyesen Pro Series Reeds, Boyesen Rad Valve Reed Cage.

 

Elev: 300 ft

 

Temp when I get the pipes: hell......could be 50 or could be 15 the way the weather has been around here. We'll say 45 degrees. I won't ride if its any colder.

 

Thanks for any info. I think "Jetting FAQ" says I'll need around 340 mains, but I'm not sure.

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Lid w/ holes is vague and could affect jetting by 2-3 sizes....Cut the last 1.5" off the end of the lid or get a K&N w/ adaptor plate and remove the lid, then jet it at 300-310 to start and do a plug test...Needle in the stock middle clip to start, stock needles and adjust air screws to throttle response and highest idle....

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HOles in lid: about 8 half quarter in diameter holes evenly spaced along the top. But I will cut the 1.5'' end off, as you recommend. I had to get the T5s, I love top end too much, and they will still have lots more midrange and low end than stock. Ya'll may see 'em back on ebay if I don't like them.

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  • 2 weeks later...

Try a 380 main and go from there....I don't think 2 sizes will make enough difference if they are that light....As far as starting hard....thats odd considering you have a 30 pilot....try turning the air screws in to .5 turn from seated...make sure you didn't swap the carb bowls..only one carb bowl has the little jet and brass tube for the choke of the left carb......

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J-Madd right on with the pipes. I payed 350 clams for mine on ebay and they are in great shape, and the guy through in the O-ring clamps for free. I'm running 340's & 30 pilots right now with my few mods and temps are in the 50's usually. It's just that i don't use an airbox.

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I'll have to try #350s. I have every jet listed from magicracing.com. #350 seems to be the biggest size. Is there somewhere else I can look?

 

Also: Which carb is supposed to have the brass tube in the bowl? I know I haven't switched them, but they could have been switched when I got it, just like the slides were.

 

Thanks Banchetta, sheeweet, spoin39.

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I'll have to try #350s. I have every jet listed from magicracing.com. #350 seems to be the biggest size. Is there somewhere else I can look?

 

Also: Which carb is supposed to have the brass tube in the bowl? I know I haven't switched them, but they could have been switched when I got it, just like the slides were.

 

Thanks Banchetta, sheeweet, spoin39.

I got mine from the stealership. Yamaha stealer can get every increment you ask for and they are Yamaha manufactured to Mikuni specs, so you need not question the quality of the factory jets. I got my summer jets and my winter jets, 320's through 350's.

 

Oh and the left carb has that choke tube in the bowl.

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