air fuel mix problems

[Xs400_4_life]

2 into 1 on and she purrin like kitten

 

[Xs400_4_life]

just took her for a spin oh my fing god im inlove all over again

 

[xschris]

You may be able to get away with the 145's. Drive the bike for a while and if there is no bogging up to the red line and the plugs look good then I would not worry.

 

[Xs400_4_life]

Ok thanks now just need some sun

 

[Xs400_4_life]

Well now i think she is running too lean in the mid range. she starts up good and idles but after riding for 2 or 3 min it dies when i stop if i dont keep it at like 3000 rpm. pulled the plugs they dont look all that ashy but ill post a pic in a few. any thoughts?

 

[Xs400_4_life]

what do you guyd think

 

[xschris]

If it dies at idle it's the pilot circuit. Do you have the idle set at 1200 rpm's when it is warmed up? What pilot jets are you using and where are the mix screws set at. The plug looks good.

 

[xschris]

If it was lean in the mid range the bike would surge or stumble in the 4-6k RPM range or at cruising speeds (55-65mph).

 

[Xs400_4_life]

It has a 45 pilot, 3 turns on the screw and is idling at 1200. It only dies after ive been riding i cant make her die in parkinlot

 

[Xs400_4_life]

and she is running really hot

 

[xschris]

What is the temp at the head by the plug. Remember these bikes run 270-290*f at the head normally.

 

[Xs400_4_life]

dont have a way to test. it just seamed way hotter then i normaly would have been when running for 30 min.

 

[xschris]

With the needles in wrong before it was most likely running cold with all the fuel it was getting. If you running ok but after a long ride it stalls out at idle maybe the tank vent is plugged and the bike runs out of fuel. You can try 3.5-4 turns out on the mix screws if the vent is ok and see if that helps at all.

 

[Xs400_4_life]

Ok ive checked the vent its good. I tried 3.5 and 4 turns, didn't seam to make any change. Its more like it dies When it gets fully warmed-up. A guy at work said it could be a lack of compression what do you think?

 

[xschris]

Have you set the valves? If not I would do that and check the compression.

 

[Xs400_4_life]

ok ill do that this weekend any tips

 

[xschris]

There are a few threads on this in the forum. I think will (bcware) even has a video on it.

 

[xschris]

http://www.xs400.com/forum/showpost.php?p=119439&postcount=14 Here is a good one. I use .004 for intake and .007 for exhaust. When turning the engine to get TDC always go forward to hit the mark NEVER back as this will put slack in the cam chain and the adjustments will be off.

 

[Xs400_4_life]

ok i got the feeler gauge and compression tester today, i did not have much time when i got home so started her up and let her run for like 20. then i shut her down and tested the right 120, then the left 90 . i will set the valves when i get home tomorrow and retest but i dont think its going to do much goo with that much of a discrepancy. any thoughts or tips on my highly probable top end rebuild?

 

[xschris]

With a cold motor put a table spoon of oil in each cylinder then do another compression test( make sure to hold the throttle wide open when doing it so the motor gets air in it.) If they both go way up then it's the pistons/rings bad. If nothing really changes then it's valves.