XP 720 Wrist pin free play

[Lloyd UK]

Hi all, new on here, excellent forum!

I have a 717 seadoo xp with a broken up small end bearing.

Have pulled the motor apart and it definately needs a new piston and bearing etc, no problem there.

The con' rod is my concern!.........

I placed the piston pin and bearing from the good side into the bad side to check for free play and a tiny amount is present, whereas when it is placed in the undamaged side, NO free play is there.

Is this going to be new rod required? There is no scoring or blueing in either the rod journal or pin, so initially I thought I had been lucky, but this 'play' has me concerned. I don't want to rebuild it, just for the little end to break up and destroy the motor again!

Cheers for any advice.

Lloyd

[wetherby]

Re: XP 720 Wrist pin free play

Hi, and welcome aboard,

Take the wrist pin out, and insert it and the bearing into the rod. Does it go in smooth, or tight. The turn it while in the rod. Does it spin free, or is it bound tight.

Either of the latter of the two, and you might have problems. I haven't seen a used wrist pin bearing with tight tolerances, as these take the worst beating with normal use.
Personally, I would buy a piston set, and do both. At this point, if it is the connecting rod, all you would have to replace is a crank kit, and a gasket set.

Del

[Lloyd UK]

Re: XP 720 Wrist pin free play

Cheers Del.

When the used but good pin and bearing are pushed into the slighly worrying rod (!), they go in smoothly and rotate fine with no binding.

If I rock the pin whilst it is in there I get maybe 1mm of free play measured at the very ends of the pin.

Also the central drive gear for the oil pump drive has shifted on the shaft and is no longer central.

I am not sure of anywhere in the UK to buy the overhaul kit or have it fitted? Seadoo dealer says new crankshaft but that is way too costly!

[John Kubiak]

Re: XP 720 Wrist pin free play

SBT exports!

[Lloyd UK]

Re: XP 720 Wrist pin free play

Hi, thanks for the post back.


Have contacted SBT before I began posting on here and you wouldn't beleive the cost involved!

$318 just for shipping, add to that $160 for me to send my crankshaft first for exchange purposes and $275 for a crank, it soon becomes very expensive!


DO SBT just sell the overhaul parts for the crank?

[seadoohx]

Re: XP 720 Wrist pin free play

i can sell you an oem rebuild.. yes.. oem from seadoo in the seadoo wrapper for 325
and you can just pay me like 50 bux for the core charge so i can buy a used core here in the states to send in..
i can have the crank shipped to you for around 40 50 bux.. thru usps airmail
sound better?

[wetherby]

Re: XP 720 Wrist pin free play

I guess next time I'll read more into a post before responding.

Lloyd, it sounds like the rod is kaput. I'd go with seadoohx on this one. Or hope to find a reputable rebuilder in the U.K.

Sorry for the confusion, sometimes I read too fast, and just get the highlites.

Del

Bubba, Texas

[Lloyd UK]

Re: XP 720 Wrist pin free play

Hi guys,

Thanks for the post back.

About to set off to work so will reply properly tonight!

Was going to get a rebuild kit from Jetskimechanic website, but will work out the costs later and let you know.

That ready built crank sounds good :emoticont

Hmmmmmm......

[Lloyd UK]

Re: XP 720 Wrist pin free play

Took the crank to an engineering company today and they said they were unable to help.


Then I had a brainwave!

Called a few motorcycle shops and one gave me a number for a guy who specialises in 2 stroke crank rebuilds. Gave him a ring and he reckons he can source ski crank parts and of course fit them. Have arranged to drop it off to him tomorrow.

Shall let you know how I get on and thought I would post this in case it helps anyone else here in the UK find help with there ski crankshafts!

[Technical Support]

Re: XP 720 Wrist pin free play

No we don't just sell rods. No you can not have any slop in the bearing to rod. You need a new crank.

[seadoohx]

Re: XP 720 Wrist pin free play

make sure hes not some backyard crank rebuilder.. these cranks spin very high rpms(7250 on my 720 hx) and tolerance is VERY critical..
make sure the crank is not bent
If he has any doubt about rebuilding it you had better run the other way...or you will be tearing it apart just as soon as you get it together..
Trust me i have been down that road.. Its not JUST a two stroke crank ..but a rotary two stroke with oil seals.. it also has the center rv gear that will give you nightmares if not perfectly centered.. and it will try to slip on you when it gets hot.
good luck

[Lloyd UK]

Re: XP 720 Wrist pin free play

I am going to be careful but am pretty happy he knows his stuff.

He prepares race team cranks and remember race 2 stroke bikes rev to well over 15,000!

Am also going to tell him that the gear must be dead central etc following your advice, thanks. oh, and also the press fits need welding on rebuild to avoid slip.

If his quote isn't much cheaper than yours for an OEM crank, then I may still take you up on that offer. How long does the shipping service you are using take to get here?

Thanks my friend,

Lloyd

[Lloyd UK]

Re: XP 720 Wrist pin free play

Well, took it to him today and what a professional setup / lovely old chap!

He has done several ski cranks b4 and before I said anything he informed me the gear had slipped and should be dead central / the press fits will need welding upon rebuild and he spotted the con rod small end problem before I told him why it needed the work. Very confidence inspiring!

He gave a 2 week / £200 estimate for the work, which includes new rods / seals / and bearings complete.

If anyone in UK, particularly Kent wants his details feel free to ask!

Will let you know how she fares following the work in a month or so :emoticont

Thanks all for your help!

Lloyd