Connecting new pistons

[Jonnyivy]

Hi,.. postie arrived today with my new piston for my 951 Di. I've read the workshop manual to see whats needed to install it and it says there should be thrust washers on each end of the roller bearings. When I looked at both the original ones (one bust, the other still okay ) there is no washers on either. So that means that there is some movement side-ways where the piston fits the connecting rod. When I bought a reburbished crank, which came with the connecting rod already attached, and the new piston kit,... neither had any thrust washers with them. Is this okay to refit them without these washers ??

Jonny

 

[ski-d00]

the original seadoo piston used a loose roller bearing system so you have to use the spacers on each side. it sounds like somebody has replaced your pistons once before. aftermarket replacement pistons usually come with caged roller bearings and no washers are needed.

 

[Jonnyivy]

Yes, your right,.. my pistons have +.50 stamped on them. All sorted now anyway, got them re-fitted tonight and all seems to be smooth while turning the crank by hand. Next stage is to lower the engine into the hull and start working out where the tubes / pipes / connectors all go...

Jonny

 

[Jonnyivy]

I'm hoping someone will jump in here with a short answer,... can you attach a piston to the con-rod the wrong way round ???? (180 degree )
It says to face the arrow towards the exhaust/ inlet ports,.... but my replacement aftermarket one didn't have one on it. (+.05)
I have already got the motor running, but its starting to splutter a bit.
Can't remember what way I fitted it, but if it don't make any differance then I don't need to take the head back off to look !

Thanks,

Jonny

 

[ski-d00]

yes, you can install a piston the wrong way. the correct way will have the the ring gaps always traveling on solid cylinder wall meaning they never go over ports. If a ring end gap goes over a port, it can easily catch the edge and rip the ring to shreds.

 

[Jonnyivy]

Ahhh,... thats the reason,.. fairly simple when I think about it !!

Thank you

Jonny

 

[needforspeed]

Did you bring your piston and cylinder to the boring guy? Reading your post it sounds like you just put a new piston in the old cylinder. I always bring the piston and cylinder to the shop to make sure there is the propper clearence. Even if it is just a hone.