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Discussion Starter · #1 ·
Can anyone help me. I am about to drag this sled soon. its an 04 mod 800 converted to the 05 mod system with the holes in the bumper for the ram air effect. Ive grew on main jet alot of times. im not sure what i am at no more now because i drilled out the jet little by little. now i am just to say as big as the tapper spot on the main jet. she is alot better than she used to be but still seems to cut out after a few seconds of full throttle on the river. Has anyone ever had this problem. Should i keep growing on the main jet? ive already contacted speedwerx and they seem as confused as i am.
 

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Had this problem once. First I would say buy new jets, if your on a low elevation id go with the stock size ( unless you changed others setting to require different than stock jetting) And of course your not really warm temps outside.

First Undo the nut on the bottom of your carbs to drain them

Make sure you have the updated carb needles, that could be an issue if you don't

Also make sure your fuel system is working ok ( i.e. both carbs getting fuel?)
 

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Discussion Starter · #3 ·
Yes both carbs are getting fuel. and the needles are stock for the mod i never touched them. no matter what size jet i put in it, it always seems to run good. plugs are brownish. but still always cuts out when on the river holding it open. ive tried restircting the air flow. and adding more air by removing the airbox cover and i always seem to have the same problem of cutting out at the end. im stumped. i dont know what else to try. my jets are far from 500's now. maybe in the 600's or even more. when i got it there were 470's in it and i couldnt even put it past 3/4 throttle it would start to bog down.. help.!
 

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Yes both carbs are getting fuel. and the needles are stock for the mod i never touched them. no matter what size jet i put in it, it always seems to run good. plugs are brownish. but still always cuts out when on the river holding it open. ive tried restircting the air flow. and adding more air by removing the airbox cover and i always seem to have the same problem of cutting out at the end. im stumped. i dont know what else to try. my jets are far from 500's now. maybe in the 600's or even more. when i got it there were 470's in it and i couldnt even put it past 3/4 throttle it would start to bog down.. help.![/b]
is there a throttle position sensor on the mods? i know we had a zr 800 at the shop a few weeks ago and with the throttle position sensor it was makin it cut out at about half throttle
 

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Discussion Starter · #5 ·
no i dont think its any sensors it always happens at top end. the engine is a speedwerx mod 800. 2004 from the factory with twin pipes. seems to me when i gun it from a stop its good until i start gaining some speed or in this case that you sayed maybe the bowls are running dry after that period of full throttle, could this be the problem. I guess maybe go to a smaller main jet and try and make the bowls keep a constant level? seems i guess like the prob that after a while i run out of gas in the carb bowls. either the pump cant keep up with the fuel supply or that some filters are restricing flow. i will check. what can i do to the need and float bowls then??
 

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Discussion Starter · #6 ·
eh boys i got my reply back from speedwerx and they sayed that the needle/seat assembly is not the problem and that there is only 1 size of those and its not the problem... so i dont know anymore im starting to scratch my head. someone must know my problem.
 

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Discussion Starter · #8 ·
there are no sensors and all gas lines are clean. some guy on another forum told me it was the pipes

Your problem is the pipes.. evey guy out here in NH that has tried to convert one, or drag one has the same issue, they have to open the stingers 3 mm minimu to get it to run wot for 5 seconds or more,, .

should i go ahead and make the modification? does anyway know for sure this is the problem. ?
 

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i hope you didnt hear that from tysqti, if thats how you spell it (hes an idiot). not alot of people here in NH are running mods, unless they have some underground acing syndicate, haha. the pipes are not the problem, speedwerx makes very nice pipes, if this was a problem they would have fixed it before they released the sled, and the throttle is help wide open for more than 5 secs on snocross
 

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Discussion Starter · #12 ·
no i did not hear it from tysqti. i have nothing much else to try. so i think i might upgrade to a couple mm bigger on the stinger part.
if you guys have any more idea's let me know. sled is parked. i dont feel like damaging it
 

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Discussion Starter · #13 ·
eh my man. i did the pipe mod like you told me. and she is still being a little bitch. here are the symptoms. if i give her full throttle from a dead stop i can hold it open for about 3 or 4 sec and she goes up to 8 000 rpm. if i gradually go up giving more and more fuel. i reach 7 000 rpm before she starts to bog out. we opened the pump. and there was fuel on the impulse side of the pump. weird i never seen that before. so we drained it and cleaned it and tighted everything up again. and she does the same thing.. anyone have any more ideas?
 

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I ran a BMP 800 w/twins and a ram-air style intake on my 03 F7 and had similar problems-finally I pulled the hood (had a Boondocker hooked up for amp. resistance) and let her breathe, and it ran like a raped-ape, so I went back to a stock air box...even though I had holes drilled through the nose cone it would pull hot air off the pipes. Just a thought.
 
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