jetting.

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coryv4

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Sep 29, 2011
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Michigan
ive been posting a few threads the last few days but winters coming lol. this is definitely a a prob that should have been addressed last january. hold tight this is a long post. ok it all started when i went to the U.P. the eleavation is 700 feet higher than where i live so if anything i should have ran leaner. anyways the day before we left i was ripping up and done my field the sled ran great plugs nice light brown. i get it up north and same the plugs were nice brown and ran awesome. on the 3rd day up there we took the trails about 200 miles with plenty of breaks for scenic pleasure. right around 100 miles is when it all went down hill. it ran great up till 100 miles but then it started getting doggier and doggier on topend then i started fouling plugs left and right. thank god i brought 10 plugs or i would have never made it back to the trailer. so i got it home at the end of the trip did all the common check ups. pulled the carbs they were clean as a whistle. checked the comp with 2 guages for accuracy and both read 140psi. pull the intakes the reads were tight and no cracks that i could see. theres obviously no air filter in the box so that throws out the dirty air filter ideas. my oil consumption stayed the same and the people i baught it from had a local shop adjust it to the manual. i went from getting 8-10mpg to 5mpg. any help would be awesome this is my only nice sled if i cant get this solved im stuck to riding the old blizzard mx.
 
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another thing i should add the temp stayed in the 15 - 25degree range the whole weekend.
 
Hell I do it all the time with my sx 700 and dont have any trouble going from 350 ft my town to 3600 ft the mountain we ride on.
 
your subtle elevation change isnt the issue, unless your jetted on the ragged edge. more importantly, what did the fouled plugs look like? oil fouled? fuel saturated?

good be an issue with the floats, could have been bad fuel, you could have been leaking fuel, but that wouldnt affect the plugs unless it was a total lean situation.
 
FJViper said:
Shot in the dark here but have you checked your plug caps? They can certainly cause problems if they are worn out. Was it all three cylinders fouling plugs? Make sure the carb vent line is still in the airbox also. Here is a link to a plug cap thread.
http://www.totallyamaha.net/forums/showthread.php?t=75436&highlight=plug+caps
Click to expand...

^X2^ Should cost you around $10-12 to rule this out. Swap out all 3 or fire up sled and see which pipe/pipes are getting hot and which arent. 700ft shouldnt make any differance, i cover bigger differance on just about every ride.
 
its a twin lol. anyways it fouled out both plugs everytime they were more of a wet fouled then oil fouled. i honestly do not think the elevationn had any play because it ran fine the firs 2 days up there. i ran what there pumps claimed was 93 oct.
 
Twins occasionaly had oil pump prob that would let oil pump run wide open all the time did one once, a 1997 vmax 600 twin my cousin had. Is oil cable adj right?
 
i would check and confirm what the floats are doing and being set at 24mm. from there make sure you have the vent hoses oriented properly. should be running down between the carbs and the engine towards the pulse line ending up between the engine mounts. the carbs can be sensitive to atmospheric pressure but usually the effect is opposite, more lean than rich, but doesnt hurt to double check the routing.

another thing that comes to mind, if your using the ngk's with the removable top insulators, loosening of those can create issues as well. usually appears as black carbon like residue on the head.
 
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