98 XPL max 6000 rpm

[Mekanix]

Worked on a friends 98 XPL last year and it was awesome. This year he takes it out and it maxes out at 6000 and gradually creaps up.

Also low end is rough and rich.

He tells me the things he tried. Like new rave valve, new plugs and new battery.

It ran slightly better with the airbox off.
Hits 7000 with the gas off and it running on what's reserved in the carbs.

So I'm thinking stuck needle and seat or needing carb kits.

Not sure what happened over the winter but going to dig into the carbs soon.

Anyone ever run into this 6000 rpm wall ?

 

[mikidymac]

Absolutely, carbs and fuel system. Don’t keep running it and without the airbox.

 

[Mekanix]

It was just a quick one shot test. As in out of the hole hit 7000 right away and off again.
Airbox back on and maxed out at 6000.
That was just for quick troubleshooting, As in rich or lean. It wants more air so its either choking for air or way too rich...

Lines and selector were all new as well.

 

[Matt Braley]

Make sure there is no water in the pump.

 

[Mekanix]

I'll look specifically for that when I have them apart. Thanks Matt.

 

[etemplet]

I will be following this... I have 98 XPL waiting in the wings.

 

[Mekanix]

Just redid the carbs. Didn't find anything

Only thing I can think of is that the needle and seats were leaking, or the o-ring around them was.

Everything looked great and clean inside and there wasn't anything obvious.
Even the return line wasn't clogged.

This worked great last year and its only after coming out of storage that this is an issue.
No precursor.

I'm treating it like its unable to reach maximum rpm.

I know it likes to be leaner on top end by removing the airbox.
I know the carbs are now good but not tested.
I know the raves are opening and solenoid works.
I know the pipe cone is getting cooling water ( hmm i wonder if the regulator is flowing too much ??
Compression is still good.

I wonder if I have a bent rod scenario here...
Or maybe somehow retarded ignition..
Or leaking reed valves. But low end is crisp and strong. so...