Runs great then bogs

[pwgsx]

Well I took my 96 XP out for the first run this summer, ran great for 10 mins and then it bogged down and wouldnt run. It would putter along but giving it any gas would almost kill the motor. Got to shore and looked it over and found nothing wrong. Started it back up and it was back to normal for about 3 mins and then it bogged again. Let it sit for about 30 mins and once again it started like a champ and ran great for 5 mins or so and then the same. I know its not the carbs as they were rebuilt last fall, I put new plugs in just in case, the ski last fall ran like a champ and was winterized. I want to say its something electrical but where do I start?

 

[Mekanix]

3 possibilities.

1 carbs are clogged again of the filters are clogged.
2 tank isn't venting or allowing air in so its creating a vaccine in the tank.
3 electrical (as in the regulator is bad ) this behaves like a rev limiter though.

Only other thing is that your running too hot and lean and its seizing when its up to temp.

 

[pwgsx]

Well when I got the ski I did the carbs, fuel lines, dumped the tank and cleaned it, also installed new vent lines and the one way valves. Im 99.9 % sure the carbs are clean. When you say the regulator going bad behaves like a rev limiter......do you mean the ski will still run but only to a certain RPM? What happens is I can be at half throttle or WOT and it just suddenly dies down to just above idle, if you give it gas it just stumbles and doesnt respond.

 

[Mekanix]

Yes it feels like its bouncing off a rev limiter set at like 4000 rpm.

Yours feels like a lack of fuel or overheating.
I'm worried its overheating, running lean and scoring the cylinders.
If its not running lean try running with the gas cap loose to eliminate the gas tank vaccume as a possibility.

What do the plugs look like when it's doing that? As in when it drops to idle. Shut it off and check plugs.

 

[pwgsx]

Ill have to check plugs right when it does it but I just pulled them and they look great, a little wet but not lean at all.........Now back in the day I had a KX250 dirtbike that ran great and 15 mins it would bog kinda like this. However it would die and you could not get it started unless it sat for over 1 hr. Then it was fine till 15 mins. It ended up being the stator was bad when it got to a certain temp. Thoughts on this??

 

[Mekanix]

Pickup coil could be getting hot and you get the same issue or same thing with the cdi but i haven't seen this myself.
I've mostly seen a lack of fuel do this if its not a regulator/rev limiter issue.
When it Boggs down can you pull the choke and recover?
also can you check the battery voltage while running. Over 13-14v and it means trouble with the regulator.

What's the compression ? Just curious.

So for the run

Check igniter coil resistance and resistance to ground.
Loosen fuel cap
Unplug regulator red wire
feel for hot engine
check plugs
try choke to see if it responds or dies.
check battery voltage while running until it acts up

 

[Matt Braley]

It's a 96..... another bad regulator/rectifier.

 

[mikidymac]

It's a 96..... another bad regulator/rectifier.

When mine went out it would run fine then loose power then only run on one cylinder then back to being fine. Runs perfect now with the new one.

 

[pwgsx]

When mine went out it would run fine then loose power then only run on one cylinder then back to being fine. Runs perfect now with the new one.

Any test for this or just replace it and see?

 

[Mekanix]

Any test for this or just replace it and see?

Unplug the red wire and run it.

 

[Matt Braley]

Yes but don't run it very long because without regulation you will be throwing too much voltage at the system in the higher rpm range.