95 XP engine surges at full throttle

[mtaylor]

i have a 95 xp 717 and at wot it surges from about 8 to 6 rpm like "vuuum vumm vumm" if you let it sit, or let of throttle it wont do it. I been through the carbs and checked everthing and it all seems fine

i had the fuel lines off the carbs and ran motor on starter for about 20 sec and it started to do the same thing when it was turning over just on the starter

any ideas?

[dsolie]

Re: 95 XP engine surges at full throttle

Any exhaust leaks? Pump in good condition (pump oil is clean and no water in it?)?

does this happen all the time, or just when the motor is warm etc.

[mtaylor]

Re: 95 XP engine surges at full throttle

no leaks , oil good

it started after riding for a while a few weeks ago

it only does it after riding at full throttle for a few seconds and keeps doing it until you slow down for a min or stop then when you go full throttle it does it again

whats wierd is that it seems to do it when its cranking as well...when I cut the fuel off to it makes me think the coil is bad?

[dsolie]

Re: 95 XP engine surges at full throttle

What do you mean it does it while cranking?? The starter only spins the motor at a few hundred RPM's.

Could be a lot of things, poor fuel delivery in one carb, faulty rectifier, fuel lines sucking air, CDI rev limit failing etc etc. Try and start with that list.

[mtaylor]

Re: 95 XP engine surges at full throttle

i mean when its turning over it goes fast slow fast slow fast slow like its doing at high rpm's when running

how do I tell if its the rectifier or other electronic parts?

[Rocky 1]

Re: 95 XP engine surges at full throttle

if it does it just tring to start it i would pull the pump and see if it does the same thing. check the pump bearings. with the pump off see if it still pulses

[dsolie]

Re: 95 XP engine surges at full throttle

I agree.. On the starter, it should be a constant spin.. Pull the pump. In post#2, that's why I mentioned condition of the pump and pump oil.

[astral]

Re: 95 XP engine surges at full throttle

Remove the pto cover from the drive shaft and remove the spark plugs and spin the drive shaft/pto over by hand and feel for any restriction.
If you think its a rectifier problem disconnect the rectifier and take the ski for a spin.