SXR 700 Perormance Question

T

tcdesignguy

New member
Joined
Sep 8, 2010
Messages
99
Age
50
Location
Lakeville MN
So in removing my airbox to get to my jackshaft I notices a lot of oil/gas sitting at the mouth of the carbs. This motor runs great but I have been chasing a weird intermittent issue where if I hold it wide open sometimes it will just go flat at 105 and if I keep holding it, it will noticably slow down. If I let off and crack it, it'll come back up to about 105. Other times, it gets to 105, then will pull again to 110-112 (on speedo).

It feels like its running out of fuel but at 7mpg I doubt thats the problem :)

Would the extra fuel/oil getting spit back out be caused by reeds not closing properly?
Plugs are cardboard brown for the most part - no snow to test this year but my recolection from last year.
I can sping my rollers on the primary without squeezing the clutch.. is this normal?
If I grab the primary at 3 and 9 i can rock it slightly, but only till a roller hits a weight... Can others do this. is this normal??
I now have a bad secondary bearing thats being replaced, but this problem has been around since before the bearing went out. I know i don't have a lot of drag on the driveline since I can turn my secondary with 2 fingers and spin my track.
It never bogs or coughs

Thanks for any help. I just want to find the problem and its driving me nuts that you never know what your going to get on top end when you floor it.
 

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I've never heard of a 700sxr getting that bad of mileage .you have a problem, those sleds should get at least 10- 13 mpg. Start by checking your jetting! even with pipes
 
good suggestions to check so far but you never mentioned the jetting specs you have in the carbs......?????

set up right,it should get 9-10mpg
 
OK I am pulling carbs tonight or tomorrow but here is what I recall.

150/150/150 Mains
3/4/3 Needles
1.5 Air Screw
I think 47.5 or 50 Pilots (I get a hanging idle on occasion so I think I need to go up a size.)

So I have brand new 147.5 jets. I think Im going to replace the reeds, and install those. Tried reading piston wash but pistons and domes are very clean. Too clean. Not sure if this is from rich condition?
 
if your running pipes ...good luck on trying to get rid of idle hang. the resonance of those pipes makes it virtually impossible to get rid of the hang!
 
To be honest if I can get the top end dialed in repeatably I don't care about the hanging idle. I have no problem bipping the choke :) I must be pooring fuel through this thing to get 65 miles per tank on 11 gallons. Not sure how if I am jetted per bender like other users...
 
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