Need some direction to improve fuel mileage

S

Southpaw

New member
Joined
Sep 18, 2019
Messages
48
Location
At home
Ok Kids, Heres the story: Couple weeks ago i finally got to get the 98 XTC 700 out on the trails for the first time. Getting 5 miles to the gallon i realize these are gas hogs but DAM. Idles good and runs smooth above about 6k rpm but wont seem to get much over 60 mph does wind up to 8k. Runs rough 2k to 6k. End of the day pulled the plugs there black as night.. OK carb problem i figured. So pulled the carbs and inspected. Now i havent done a full breakdown yet... Checked for correct jet sizes, checked float heights, Checked fuel enrichment seals all seems well. Have not confirmed needle setting and found pilot screw for PTO side out 2 3/4 turns other 2 out 2+ turns. Book says 1 1/2 turns. Dont think thats the smoking gun but im just learning about flat slides so maybe?? Looking for some thoughts and direction maybe something im overlooking. Thank you in advance
 

damn. is that thing geared for the mountains or a really long track? that sled should be averaging 11-13 mpg all day as a 121 or 136. i would start with checking the reeds and then pull the clutches apart and clean them. throw a new primary spring on it and a new belt and see what it does. sounding like belt is glazed and clutches are slipping. that sled should rev to 8600 +/- 100 rpm.
 
I think the the clutches are definitely in need of attention. Thinking the poor fuel mileage is a combination of the fuel mixture incorrect and worn out clutching. Is it common to lower the needles on these one notch. All my running issue seems to be between 1/8 and half throttle??
 
I would go through the carbs with a thorough cleaning, don't forget to look closely at the pilot jets and the needle/seats. Also go through the clutches, clean and replace any worn parts.
I wouldn't adjust or change anything (except getting the pilot screws where they should be) until knowing both are clean and in good condition. Then run it and do plug checks at low, mid, and peak rpms to know how jetting is. Dirty carbs can give you very false jetting readings.
 
Being so fare out on your idle screws will affect alot! I run mine at 1.75 turns out. Factory stock 1.5 is a tad too lean, and 2 turns is super fat and performance is effected off the launch...

Many do ( as me) runs the needles one full notch dropped with two washers under with excellent results
Across all three carbs. I have excellent mid range response from this. But your area and fuels may lead to a slightly different combination to be optimal
 
Last edited:
Vincent said:
Being so fare out on your idle screws will affect alot! I run mine at 1.75 turns out. Factory stock 1.5 is a tad too lean, and 2 turns is super fat and performance is effected off the launch...

Many do ( as me) runs the needles one full notch dropped with two washers under with excellent results
Across all three carbs. I have excellent mid range response from this. But your area and fuels may lead to a slightly different combination to be optimal
Click to expand...
Don't understand the washers under the needle. I have done that with needles that aren't adjustable to fatten up the mid-range. Are they thinner than the distance between clip settings?
 
Yes they are an "inbetween" notch adjustment. Factory stock is 3Rd notch on the needle with two washers underneath the E clip. If your carbs needles don't have the two plastic washers under the clip, someone has removed them.
 
Last edited:
I found those washers guys seems someone has already moved the E clip up one notch already. Got the first carb stripped down and through the ultrasonic cleaner and reassembled. Boy these flat slides got a lot of parts. Im really missing the old CV's and round slides LOL
 
Your poor mileage is because the main nozzles are worn out. However, they are starting to discontinue this part.
 
You must log in or register to reply here.


Back
Top