Seadoo XP bogging down/misfiring

[RyanNZ]

Just brought a 1999 XP LTD 951, rebuilt by previous owner but never run in and has been sitting for a couple of years.

Ran fine for the first hour, then suddenly it started bogging down between 2500rpm and 4500rpm. It bogs down and tries to die, and starts surging etc (as if not getting enough fuel). Have pulled the carbs apart and cleaned everything and pulled jets out, but now it's even worse and bogs down at all revs, and will die unless the throttle is held wide open (even then it misfires and splutters, and revs won't go past 5000rpm).

Have replaced the fuel hose, and cleaned the three filters (main filter and 2 x carb filter). Seems to be good fuel flow right to the carburetor. Has fresh 95 octane fuel in the tank (only 10L or so). Have low speed mixture set at factory setting of 1.75 turns, and high speed is wound right in (lean, as this was how it was from the start when it used to run ok). Any other settings I may have incorrect?

So gutted as I purchased it for the holiday season but it's not going! Any help would be much appreciated.

 

[Dr Honda]

Take those carbs apart. If you continue to run the engine that way... you can burn it out.

 

[RyanNZ]

Have taken them apart a couple of times and cleaned out but nothing changes - if anything just gets worse

 

[SabrToothSqrl]

New?

when I rebuild an engine I add oil to the gas for extra lube for break in.

this usually destroys the spark plugs... (clogged with oil gunk)

have you tried new plugs or how do they look?

 

[djredman99]

You should check the compression on the cylinders as well.

You say you have taken the carbs apart, but other than cleaning it have you actually rebuilt them? Tested Popoff pressure? Re-Jet?

 

[kcr357]

Check the diaphragms for a red anodized nub in the middle, if it's uncoated alum. it's aftermarket, throw them away and get genuine mikuni.

 

[Chester]

You might have a bad voltage regulator. Check the voltage at the battery while revving the engine up to about 5000 RPM.

Chester

 

[RyanNZ]

Have put new spark plugs in, no difference.

I've checked compression, and both cylinders are exactly the same at 105psi, I realise this is low but I'm sure it's due to the fact it's still being run in? Its only had about 1.5hr running time if that.

Chester, I've put a voltmeter on the battery and revved to 5000rpm, doesn't go past 12.5V approx., so I'm guessing this means its ok as it isn't going past 15VDC?

Diaphrams have a red anodized stub in the middle, so must be genuine Mikuni?

Djredman99, I havn't tested pop off pressure as I'm not sure on how to do this or have a pump to test it, any basic ways of going about this?

Many thanks in advance.

 

[Chester]

It's not charging then. What was the voltage when the engine was not running? You should see an increase in voltage when you run the engine, not a decrease.

Chester