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Discussion Starter #1
I have an 800 twin and have seen alot of posts referring to the lean spot between 6-7000 rpm.I know the needle has no adjustment on it so why cant you just add a shim or two to give it more fuel in the mid-range.I have an EGT 5/20 needle shim kit that i used to fine tune my triple with so why would it not work on the non-adjustable twin needles or am i missing something here.
 

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The needles are pressed into the slides. They can be changed with ones with grooves from the 2000 MXZ800.

The problem is that you can get the pilots perfect, and the WFO perfect, but it is lean in the middle. Fix the middle and it is real rich on the top. Start messing with compression/ and or timing and it gets even more critical.
 

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800 X,
You should be OK to experiment with the shim kit. On my 01 800, the needles are not pressed in just the needle jets are. I have not tried shimming the needles myself, but I've talked to people that tried it. No one has had complete success yet in getting the results they wanted. Let us know if you find the right combo. :D
 

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I assumed that the needles were pressed in, cause for 2002 Doo had a recall on them to verify where the needles were positioned. Just an assumption from the info I was told.

To me, the fix might be using a power jet system. Work on the timing of the sytem and you could "squirt" the gas in the midrange.
 

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I think mxzwfo tried that ,and I dont think he had any luck.
 

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DAMON from GLH RACING has found the culprit and knows how to fix it. It is the jet needle i believe and when he gets done with the grass drags he will have the new jet needles available.
 

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I believe this is the adjustable needle number that works, it came out of the early release 800's.
Ski Doo J8-9HIY01-52
 

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Discussion Starter #8
Good info guys,i've been running a speedwerx head and had no idea about the leanspot until i saw it on here.I will have to rejet my sled to be on the safe side.The head is useless so i might as well take it off.Has any one tried one of Cudney's heads he sells on his website?
 

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I have one on my "02" Summit, the only advantage is being able to jet down, Im running 440 mains, with the J8-9HIY01-52 needle in the #2 position, because of jetting down my milage is up, also noticed an increase in power. I think the lean spot is not an issue, its  more of having the EGT probes mounted in the wrong position.
 

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Hard to say what is happening, at trail cruising speeds the exhaust could hang up on the egt probe and give a false reading.But I tend to beleive what the egt guages tell me.I believe glh racing said he was going to try his fix when he can field test it on snow and then let us know. 800x, give bill a call he has alot of info on the 800 twin .pick his brain
 

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If you move the probes 6" from the cylinder it will read true, the only problem is than your into a single probe position because you are behind the Y pipe. I found this out doing testing with a Stutter Box. I ran through all throttle positions stock and that went off those readings. And your right when I tested in the Y pipe I did read high in the mid range.
 

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I have found through dyno testing as well as trail testing that the ski-doo manual is very close.  At 1350 on the temp guage I started to detonate.  I use the manual as a strict guide and after enough holed pistons with probes in the center position I decided to believe the temps at their recomended position.  This has kept performance and piston troubles at a minimum.  I tend to jet on the safe side for lack of noticable performance when on the edge.  Just my experience.

GLH
 
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