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Discussion Starter · #1 ·
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Originally posted by: 1111
well for me jetting the dual carbs is a maybe 20 minutes at tops for me i find it pretty easy i know i know others hate it but for me i have gotten good at it and frankly plan ahead depending on riding site and yes i have had the carbs out and on there top sides in the middle of a rideing day yes not what i want to be doing but for me i can do it lol again happy riding
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I prefer carbs over EFI myself. EFi is great for quick starts, alt and temp changes. But, if doesn't have an integrated mass air flow sensor, it requires recalibration after mods. Also, EFI is not a reponsive as a good flat slide carb with accelerator pump.

But, the Raptor CVT carbs are a major misapplication. These are street bike carbs. Yamaha should be shot. They are unresponsive and difficult to tune. The vacuum slides are designed for smooth roads, not off road. Bouncing slides make the bike sputter. Bouncing floats require periodic adjustment. I have been fighting these carbs since the bike was new. Finally, the torsional throttle plate return spring broke 70 miles from home in the desert. (I was WOT at the time...scary) Jury rigged the return with the brake light switch spring. This was the last straw for me. So, I just ordered the 39 mm FCR flat slide carbs...thanks to this thread. Should have done this a couple years ago. So, I hope the bike stays together for a while now. I am stuck with this bike for a couple more years now...which is just fine.


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2002 Raptor
Craycraft 690
CT Exhaust

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DuneMe
Pro Rider
Elk Grove, California

Posts: 3247
Joined: Jul 2002


Sat May 05, 2007 2:58 PM



You are going to love those FCR's. . . I was thrilled with the performance of them on my DS. . . Good comments on the stock carbs. . .

What some will have to decide is, do I want to put $1000 into carbs/intake/filters AFTER I spend a bunch of money on mods or should I go with the FI.

The FI does require re-mapping because it is not a closed-loop FI - Meaning - it isn't reading the exhaust gas O2 % and adjusting the fuel/air ratio as conditions change. . .

There is something in the inlet air plennum. . . I assumed MAF (Mass Air Flow) Sensor but, I guess it could be temperature sensor???

The Fuel Injection system on the Raptor 700 will compensate for changes in altitude (atmospheric pressure) and temperature. . .

If you modify the pipe / air filter to allow for more Air Flow - you need to change your fuel map (PowerCommanderIII is great for this.) It doesn't require any removal of plastics, spilling of fuel, dropping of jets, etc. Just plug your laptop into the USB port and fire up the bike to get the connection and download a new map or change the current map. I would suggest making changes to the map on your Laptop first then save it as a new file. Now you just need to connect and fire up the quad to get the connection and download the map to the PCIII and you are done.

Both my Wife and I could change the jets in the carbs in about 30-minutes. I think I'll be able to re-map the 700 in about 5 minutes. AND I won't have to get dirty or get out any tools!

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2007 Raptor 700 - Mine - How can I make it "Jetted" so I can go really fast!?!?!
2006 Raptor 700 - Wife's
2006 Honda 250EX - Daughter's
Tom Pro Mini-Rail - 300HP in a 900lb. ride. . .

2005 GMC Duramax pulling
2007 WWLE3905

Brotherhood above all else. . .
Except Honor!

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Discussion Starter · #2 ·
i just bought a 05 660.. dont know anything about fixing. now i'm alittle worried i'm going to have problems :unsure: sometimes the internet can be a bad thing :grin_nod: too much info you dont know who to beleive :help: :eek:
 

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Hey I recognize that thread. ;)

Don't be worrried, don't be freaked out. The carbs are not the most efficient and they can be difficult to tune. They're not as responsive as they could be nor are they as easy to get the bike started with as an EFI system.

But with all of that said they are reliable and anything short of running a full blown MX race or running through the desert at 80 miles an hour you're not likely to feel any kind of issues with the carbs losing vaccum. And even in those situations it's usually not debilitating.

If you're a weekend warrior or a recreational rider then you'll be ok with the stock carbs. Yamaha has sold so very many of these bikes with tens of thousands of happy customers that use stock carbs. It's just that on the internet you get a lot more people who are dedicated to improving their bike and making things better and faster than you're ever going to see on the trail and sometimes that can make some situations or parts seem worse than they really are for the average rider.
 

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Discussion Starter · #4 ·
hey mike, as always thanks for all your knowledge :thumbsup: what if i wanted to do a basic rejet , lid mod and exhaust :3question: is that a fairly reliable mod if you know what you're doing without any problems down the road :help: i'm talking the most basic rejet / exhaust swap. i have a guy that has a yamaha exhaust( forget what brand he called it/ its not yamaha i dont think) on his raptor that he's parting out.
 

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The carbs will work fine all the way up to about a 200 main jet. At that point they just can't get the vaccum to pull everything through.

You'll be fine with a rejet for a new exhaust. I ran stock carbs on two different bikes over the course of 3 years and never had any failures of the carb or its components. Now getting the jetting just right, that can be difficult but it's entirely possible. Most people can get it pretty darn close on their own.
 

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Discussion Starter · #6 ·
8) in regards to rejetting. there is alot of dyno tests out there that show very little gains. my question is this : can you know what part of the powerband/ or gear you will see gains or will it be across the board ? :3question:
2 - i know when you change sprockets you either get more top end or more bottom end. i was riding with a 06 yfz this past weekend that is piped and jetted and diff. sprocket. the gps was giving him about 10mph more top speed. if i were to change sprocket i could come closer to him top end right ? :3question: and not give up low end speed because of the rejetting ? :3question:

this is of course for my bike application stock 05 660 .. i do out weigh him though by about 75 lbs.


by the way : you know i was concerned about handling on the 660 and this was my first raptor what to expect post.. the trails were closed here in minnesota?? well, i took it out last weekend , and absoloutly loved it !!!!!!!!!!!!!!!! i was definetly able to power slide w/ the 1.5 " spacers although not as easy as with the 400ex.... thanks for all the anwsers :thumbsup:
 

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Discussion Starter · #7 ·
hey maddog just saw your post under 660 mods :thumbsup:. forget this last post. :grin_nod:
 

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stock carbs are fine. mine are jetted right and never fobble. Always starts right up even when not run in a while. maybe some just get lucky.
 

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I can easily say I haven't had any problems with my stock carbs. I rejetted when i changed my exhaust and air filter. I had a slight pop on the decel, so i bumped my pilots to 25s. I needed a total of two rejets to get the plug to the color i want.
 
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