2003 Yamaha XLT 1200

[Aughrim]

2003 Yamaha XLT 1200 seized on number 3 piston and starting to seize on number 2.

Jet ski was a Japanese Ski that was imported into Ireland. Customer ran it for a short time when imported first it was down in power so he got another shop to carry out a top end re build where they fitted WSM pistons and bored and sleeved cylinders rather than plating. Jet ski was returned to customer from previous shop with it making a loud knocking sound on rev up. He continued to use it for a short time until it got worse and brought it to our shop.

I did a compression test and removed the cylinders showing the damage to the second and third piston.
Informed customer and it has sat in storage for the last three years while he decided what he wanted to do.

It's now back on our shop to get repaired.
It's hard to get anyone that actually has the knowledge to know what caused it in Ireland and someone who doesn't want to cut corners on a rebuild, so any help would be appreciated.

I'm not sure if it's been an issue since this ski was imported that's caused it or since the other shop did a top end rebuild.

Would the jetting I presume be different from Japan to Ireland? Main jet 112.5 and Pilot 95 currently fitted.

What quality are WSM pistons?

Is it better to try get new cylinders rather than re bore and oversize sleeves already fitted?

The customer wants to try use genuine or best quality parts as he doesn't want to have issues in the future and wants to keep the ski even though it would be cheaper to get a newer replacement.

I will attach pictures that hopefully might help, oil pump is still fitted, on the side of Ski it has Factory pipe fitted so I'm not sure if cat is fitted, I didn't get to look at the exhaust yet.

Also on the crankcase between the 2 and 3 cylinder where the two bearings sit seem to have wore into the bottom crankcase leaving a slite lip between the bearing each side and the labyrinth seal.

 

[WFO Speedracer]

Does the Japanese model even have a Catalytic converter in it or is it like the European model.

Stock jetting on US models is 117.5 main and 87.5 pilot jet , does it have accelerator pump carbs , I am trying to make some sense out of those jetting specs.

Way leaner main jet on a ski that already has too small main jets on it and much larger pilots , weird , maybe with that big of a pilot you can drop the mains down that low using the stock restrictive airbox , not sure on that one. Jetting depends on altitude

My guess is it going to depend on where in Japan their elevations are all over the place but the two big lakes Biwa and Yamanaka are vastly different altitudes Biwa is at 276 ft and Yamanaka is at 3217 ft.

I guess what matters most is what altitude are you setting it up for now ?

 

[Aughrim]

I'm not sure about it having Catalytic converter, will be able to check in the morning.

I'm not sure about accelerator pump carbs either. I think it does have, how can I tell which carbs it has?

I'm not sure what part it came from but knowing it was imported from Japan raised a flag that it might be jetting issues that is causing seize?

It will be running in an altitude around 185 ft.

 

[WFO Speedracer]

Those jetting specs I posted for the European model skis should work for you then, I just wanted to make sure you were not at some high altitude.

My suggestion is rejet to those specs and ditch the Cat and the oil pump, premix it at 50-1 , If the customer does not want to premix the leave the pump, run all new lines and safety wire everywhere the hoses connect , no zip ties , also change out the power -valve lever links or install Waveeater clips , if it's already apart I would do the lever links personally.

My concern with the jetting you have now is that sounds ridiculously lean on the main jets to me, if he want's it all stock go with the European jetting specs , if he will go for individual flame arrestors go with O-side bills jetting specs , but it will run a lot better and be more reliable with the O-side Bills specs..

Choke shaft removal , there are a lot of opinions on this , here is mine don't do it , I leave the choke shafts alone and just pull the cable out and replace it with a primer , if you do pull the choke shafts out only use the O-side Bill jetting specs and those only work with aftermarket flame arrestors.

I put primer kits on these skis because otherwise you will wear the starter out trying to crank them , when hooking up the primer buy a tee fitting for the primer line, cut the accelerator pump line exiting the pump and tee into that line with the tee fitting, it makes for a really clean installation that is reversable and since the acell pump nozzles have check valves in them even if the primer goes bad it cannot suck fuel in through the primer lines, not possible .

Cylinders , personally I would find a set of good used cylinders or buy new ones from WSM , the cast iron relined cylinders have to run way more clearance because they cannot dissipate heat they way the Nikasil cylinders can, the Nikasil cylinder offer almost instant heat transfer, the cast iron cylinders are well cast iron which retains heat , most of his noisy engine probably stems from the almost double piston to wall clearance needed to run those pistons in a cast iron bore.

You can always buy three pistons and have those cylinders bored and sell them to someone that doesn't know any better SBT does it every single day.

Barring something metal getting loose and running through the engine or an oil line coming loose those Niakasil cylinder will last forever especially if you premix the ski .

Pistons WSM make excellent pistons , on these I would rather run WSM , Pro X or OEM pistons , either one will work just fine , the nice part is if you order the WSM cylinders and piston you just put it back together with no worries about clearance .

I think you already know these are very expensive engine both to buy parts for and to build laborwise, don't let the customer undercut you on the price , especially if no one else there want to foll with it , good work isn't cheap and cheap work isn't good.