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99 xc 700 carb help

brianxc700

New Member
Messages
3
Age
51
Location
ohio
Country
USA
Years Snowmobiling
30
Snowmobile
xc 700
indy trail
last fall i pulled carbs and took bowls off and sprayed them out with carb cleaner and replaced all fuel lines .didn't fire it up till now . cold it fires up sitting there warming up at idle it hiccup's and dies . if you give it some throttle before hand will stay running but bog's down a bit and just smokes fiercely . rode it and it runs very well no problems mid range or top end . while it is hot idling no smoke but after 15- 20 seconds it will hiccup and die . rideing and stop and idle 6 seconds it ok seems like the longer it idles is when it dies . pulled the plugs and they light tan perfect not to rich .
cold it only idles about 1100 rpm i thought about turning the screws with black knob on the side in a bit should make it idle faster? theses are the keihin d slide carbs they were pretty clean when i pulled the bowl off the bottom . any input on this appreciated
 

850Switchback

Member
Messages
51
Age
45
Location
CT
Country
USA
Years Snowmobiling
30
Snowmobile
2020 Switchback XCR
Yes the black knob is the idle adjustment. Did you mess with the other screw( air screw) on that side of the carb? That will affect idle as well, should be out 1.5 turns.
 

brianxc700

New Member
Messages
3
Age
51
Location
ohio
Country
USA
Years Snowmobiling
30
Snowmobile
xc 700
indy trail
Yes the black knob is the idle adjustment. Did you mess with the other screw( air screw) on that side of the carb? That will affect idle as well, should be out 1.5 turns.
well i got to messing with this today and the air screws on both carbs was only turned out 3/4 of a turn . i turned them out 1.5 turns and went one flat in on the black knob screws . fired it up and seemed to make a difference it stayed idling without snorting and bogging out and dyeing. only way theses screws would have got turned in to 3/4 turn would been done by my dealer when it was there 6 years ago and then it was riding in the UP Michigan after that was the last time it was rode .
this should only affect the idle mixture right ? don't want to burn this down
 

850Switchback

Member
Messages
51
Age
45
Location
CT
Country
USA
Years Snowmobiling
30
Snowmobile
2020 Switchback XCR
The pilot circuit is always adding fuel and controls from idle up to 1/4 throttle.
So its definitely rich if that cleaned it up, but sounds like its still not right. I found the settings for 99 and turns out that screw should be at 1 turn, which would be less air and run richer. The 1.5 turns was from my 2000 700 service manual even though the carbs are the same. That pilot circuit was always a headache in those sleds.
Something is still adding fuel that shouldn't it sounds like if it ran good at the old settings the last time you ran it 6 years ago. I would check the floats & fuel needle to make sure there's no dirt hanging it open slightly, there's no seat in a Keihin or else I'd say replace that. Also check the chokes to make sure they are clean and not possibly leaking.
Another possibility is the reeds have gone bad. As I mentioned in another thread recently one of my friends has a 02 600 he bought new for the wife that saw little use over the years, pulled it out last year for his son to use and it wasn't running right at idle. The reeds had lost alot of tension from age and were no longer fully closing. Does it look like its spitting alot of fuel/oil into the airbox?
 

brianxc700

New Member
Messages
3
Age
51
Location
ohio
Country
USA
Years Snowmobiling
30
Snowmobile
xc 700
indy trail
The pilot circuit is always adding fuel and controls from idle up to 1/4 throttle.
So its definitely rich if that cleaned it up, but sounds like its still not right. I found the settings for 99 and turns out that screw should be at 1 turn, which would be less air and run richer. The 1.5 turns was from my 2000 700 service manual even though the carbs are the same. That pilot circuit was always a headache in those sleds.
Something is still adding fuel that shouldn't it sounds like if it ran good at the old settings the last time you ran it 6 years ago. I would check the floats & fuel needle to make sure there's no dirt hanging it open slightly, there's no seat in a Keihin or else I'd say replace that. Also check the chokes to make sure they are clean and not possibly leaking.
Another possibility is the reeds have gone bad. As I mentioned in another thread recently one of my friends has a 02 600 he bought new for the wife that saw little use over the years, pulled it out last year for his son to use and it wasn't running right at idle. The reeds had lost alot of tension from age and were no longer fully closing. Does it look like its spitting alot of fuel/oil into the airbox?
the airbox dry . i do have some aftermarket reeds in this put them in around 4k miles it has 9500 on it now . also rebuilt the top end (pistons rings ) only has 1k miles since . found a polaris service manual online and thought about pulling the choke plungers out and checking them and also thought of pulling the air screws out and lightly blowing some air in passage . i didn't mention i had some mice get into this couple year ago they chewed right thru the foam cleaner in hood and had bird seed in air box all the way into carbs .that is when i took them off and blew them out and sprayed carb cleaner thru everything DAM MICE !!!. like i said only at idle this thing runs great mid to wide open it will stretch your arms out hanging on. ran 1 and 1/2 tanks gas thru this and had it treated heavy with seafoam to help clean anything out
 

850Switchback

Member
Messages
51
Age
45
Location
CT
Country
USA
Years Snowmobiling
30
Snowmobile
2020 Switchback XCR
Check the choke first, I vaguely remember having one stick on reassembly once. Its possible something is in that air screw as well given the mice issue. Hopefully nothing got past the carbs and into the reeds, if they are Vforce Delta 2's you might want to check them as there is an updated petal available for them since the originals had issues.
 


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