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I'm building the motor on my old mxz 670 and was wondering about how well the ufo's would work. Modd's include cylinder porting, tunnle porting, crank shop rv cover, and twin pipes. I'v read that the ufo's add awsome throttle response and more mid range and top end, so with what i am already doing to the motor they should give me a little extra. But i'v also read and heard that if not set up properly you can melt your motor real easy, anyone with any experiance with them i would love your input, thanks.
 

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I installed UFO's on my 2000 Formula Z 700( blue printed, ports ports polished and chamfered, head milled,MBRP Trail) and I love the throttle response. They give you a templet to shave and shape your carb slides. You must drill a hole into your slide and tap it. You must take your pilot jet out and put one in that is half(45 TO 22.5) the size. Yoy can drill a #55 hole into your needle jet( hepls in fuel milage), you may want to start smaller to be careful because you can damage your engine in a heart beat. I dropped my main jet one(300 to 290), run it and check plug color and piston wash. You can also call Thunder Products and they will help you with dialing it in. Just make sure to take time and read install directions. They helped me out.

Just my .02



FZ700
 

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UFOs are like 60 bucks or so, i bet you could find a good set of flat slides(used) for a few more dollars, then once you have those set-up, you don't have to worry. you already spent the cash on the engine work, why not spend a few more on some true flatslides
 

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I never sen a set of flat slides on any Rotary engine! It takes alot more than bolting a set of flatslides to engine! Dennis kirk $169.99 per carb.

FZ700
 

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I dialed in and used UFO's on my '97 Mach 1. I had awesome throttle response and acceleration but only 4-4.5 mpg even after drilling 5/16" hole in middle of UFO slide, so I took them out for winter trail riding and only use them for summer grass drags now.
Just my experience with them !
 

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Ihave UFO's in my 670 and love them. Excellent throttle response! You have to watch your jetting until dialed in and then forget about them. They improve low and midrange, not so much top end. Drilling the hole in the needle jet will improve you fuel mileage they say, although Thunder Products did not recommend this for 10,000 ft on the 670. I did not drill the hole and have the exact same fuel mileage
 

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This is the set up in my 98 Form Z 670 that I'll be trying this winter with twin pipes ! 2.5 ufo's with 25 pilots, 224 aa-3 needle jet , 7 edy1 and 4th clip position from the top . My 95 SS has a similar set up with a single pipe . Last winter I was using 1 to 2 gallons less per fillup than my buddies 2000 MXZ 700. On the lake it wasn't even a contest , had 6 to 8 sled lengths on him. Oh yea I used EGT's to get dialed in . Good luck
 
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