1995 XP Rebuild

[NoahDobie]

I rebuilt the fuel pump and pulse cover again, so that must be good if there was an issue. It will fire right up if I crank it but it only 1 cylinder seems to get hot after I run it for about 15 seconds. Only the PTO plug gets warm, but they both are getting spark. I think this is the problem with the ski, not the carbs.

EDIT: Yep, confirmed it. Its running intermittently on 1 cylinder but it cuts out a lot. Sometimes it will run great, but most of the time its running off of 1. Was able to pull the mag boot and it was still running at 1600rpm.

 

[JeremyD615]

What’s your compression at now? If you’ve got fuel and spark, there’s no reason it should be running on one cylinder...

 

[NoahDobie]

Compression is about 140 in mag and 145 in pto cylinder when its cold. Which seems low for a fresh motor. Anyways... it will run for about 2 seconds properly when I first start it and then runs off of 1 cylinder but if I give it some throttle it seems to run on both. So I think it has something to do with the low speed jet or adjuster on the Mag carb. Is this a common issue?

 

[mikidymac]

Not sure on the 1995 but the 1996 will do all kinds of weird things when the voltage regulator goes out. I would try running it with the red wire disconnected from the voltage regulator.

 

[NoahDobie]

Well, I guess I've narrowed it down now. I took off the red wire off the regulator and it ran the same. When its been sitting overnight and I fire it up it runs good, idles at exactly 3000 for a few seconds on startup then it dies off in the MAG cylinder. If I give it throttle it runs perfect. So it must be something to do with the low speed jet or the low speed screw. Not sure why though, I have unplugged all the jets and everything is on stock settings. Any ideas?

 

[NoahDobie]

Went through the carbs again cleaned everything... still no luck. One cylinder doesn't work on idle but if I give it throttle they both go. Do I bite the bullet and get a new coil? Thats the last thing I can think of

 

[JeremyD615]

The one coil fires both plugs, so I don’t think that’s your issue. Did you make sure the carbs are in sync? Maybe one is closed while the other is cracked enough to idle...

 

[NoahDobie]

Yep, they are fully synced up. All settings are exactly the same. I'm thinking it might be something to do with the needle and seat on the mag side carb... not sure, but I might as well try it. Seems pretty hard to find the 1.2 needles around here though, and I really don't want to order it and waste even more time...

I had almost perfect pop-off though, so really not sure if the needle is what it could be.

 

[NoahDobie]

While, I'm waiting to find some needles, I was messing around with he buzzer, because it doesn't work, I tested it with a battery and nothing, but even coming from the connector it is putting out .12 volts when the key is on? Is there possibly a bad ground that is causing the other issues as well? or is it something with the mpem?

 

[JeremyD615]

Yep, they are fully synced up. All settings are exactly the same. I'm thinking it might be something to do with the needle and seat on the mag side carb... not sure, but I might as well try it. Seems pretty hard to find the 1.2 needles around here though, and I really don't want to order it and waste even more time...

I had almost perfect pop-off though, so really not sure if the needle is what it could be.

I’m not taking about settings being different, I’m taking about the physical linkage being synchronized. If you have one carb completely closed at idle and the other cracked open, you could see the engine idling on one cylinder.

 

[NoahDobie]

I’m not taking about settings being different, I’m taking about the physical linkage being synchronized. If you have one carb completely closed at idle and the other cracked open, you could see the engine idling on one cylinder.

Yes I set the linkage correctly. They are both open the same amount

 

[NoahDobie]

Messing with the carbs again, ordered new needle and seats because the ones in there were 1.5 and I need 1.2, so I figured that must be part of the problem. But no matter what I do when I try to test pop off air leaks out of the needle when I try to put the new 1.2 in. Any ideas?

 

[JeremyD615]

Messing with the carbs again, ordered new needle and seats because the ones in there were 1.5 and I need 1.2, so I figured that must be part of the problem. But no matter what I do when I try to test pop off air leaks out of the needle when I try to put the new 1.2 in. Any ideas?

Where did you get the needle and seat? They were replaced as a set, correct?

 

[NoahDobie]

I've now put some brand new genuine mikuni 1.2 needles and seats into the carbs. Also bought a mint condition MAG side carb to replace the old one. They are both popping at about 51psi and holding pressure nicely. When I turn the gas to the on position and leave it for a while it fires up instantly and at a good rpm. Then after a few seconds it will die out in 1 carb, now it dies in the PTO carb since I've put the new one on. It will die in the one then idle around 1600rpm and as soon as I give it a little bit of throttle it will shoot up around the right rpm. So then I turned the idle adjuster up about a half turn and it worked better idling at almost exactly 3k rpm and I could rev it and everything. So now, everytime I start it the engine seems to start up on the MAG cylinder and after about a second the other one kicks in. Is this normal or has anyone experienced this? I feel like I'm so close now.

I have a video I posted so you can see what I'm talking about. About halfway through I cranked the idle adjustment screw up and then it sat pretty nice around 3100 rpm. Now this is how I've left it, but when I start it now with these settings it seems to fire up on the MAG side cylinder before the PTO side.
Video Link Here