97 xp hard start runs really rough

[Tylorharoldson]

Hey guys,

I'm beyond confused. I recently purchased a 97 xp and can't seem to get it running right. When i bought it compression was at 140-150.

I rebuilt the carbs
Put new gas in
Replaced the fuel lines that go to and from carbs
New starter
New solenoid
New spark plugs

Even after all of that I can get it to start, ONLY by putting gas directory into the cylinders. It takes a while and will only fire up after a few seconds of holding the throttle wide open. Even when it's running, it's running really rough and sputters. I'm ready to leave this thing at Lake and never look back.

 

[JJinSC]

One simple thing to check first. You could be drawing air. Did you replace the fuel selector valve and o-ring on water separator filter?

 

[Tylorharoldson]

I did not replace either of those things. To be honest I'm not quite sure what exactly those are. Also When you say "drawing air", would that explain why when I take my gas cap off it sounds like I opened up a shaken bottle of soda?

 

[Trooper182]

The fuel selector valve is the valve the fuel on/off/res knob is attached to. The o-ring is on the plastic bowl that the fuel filter is attatched to

 

[JJinSC]

I did not replace either of those things. To be honest I'm not quite sure what exactly those are. Also When you say "drawing air", would that explain why when I take my gas cap off it sounds like I opened up a shaken bottle of soda?

That symptom indicates your fuel vents are not working properly and depending which one is not functioning your are either creating a vacuuming creating a no fuel condition or excessive pressure which can cause your engine to flood. See how it cranks and runs without the fuel cap on.

 

[Tylorharoldson]

That symptom indicates your fuel vents are not working properly and depending which one is not functioning your are either creating a vacuuming creating a no fuel condition or excessive pressure which can cause your engine to flood. See how it cranks and runs without the fuel cap on.

Thanks for the advise. I tried it without the cap on and the same symptoms appeared. I also cleaned the fuel selector (didn't replace) and did replace the o ring on the fuel filter. tried starting again and it ls the same thing. Will only start with the throttle wide open. Once started it sputters and sounds terrible.

 

[JJinSC]

Replace the fuel selector. You cannot clean them and when you try it makes them worse. They are prone to letting air leak in to the fuel delivery system.

 

[Tylorharoldson]

Replace the fuel selector. You cannot clean them and when you try it makes them worse. They are prone to letting air leak in to the fuel delivery system.

Will do! I'll let you know how it goes when get it in.

 

[mikidymac]

Did you use genuine Mikuni parts for the carb rebuild?
Did you replace the needles and seats?
Did you change the pop-off springs?
Did you test pop-off and leak down?

 

[dr00andrew]

Even when it's running, it's running really rough and sputters. I'm ready to leave this thing at Lake and never look back.

dont leave it at the lake and never look back. believe me, i understand how frustrating it can be when you are working on something and just cant get it to run right. you are getting some good advice from well known users on here. try out what they are saying and eventually you will get it. you have good compression and thats the biggest part of the battle