Piston Clearance

[Big Kahuna]

I dont. Just try and make you think that I might.................

 

[Freakrider]

all pistons can be seizeco's
its all about how to setup the engine package
you should know...you have been here a long time and that was a lame statement
do a search plenty of seized cast pistons
its the nature of the beast with a open water cooling system

granted the wiseco yamaha 760 piston #757mo8500 are heavy and need to be clearanced more
wiseco stopped the pro-lite series a long time ago unfortunately for us performance nuts

Do you mean Wiseco stopped the pro- lite series for the yamaha sizes ? Reason I ask is because Weisco still sells the Kawasaki 750 flat top pro- lite that are used in the XS900R.

 

[Dartman]

Do you mean Wiseco stopped the pro- lite series for the yamaha sizes ? Reason I ask is because Weisco still sells the Kawasaki 750 flat top pro- lite that are used in the XS900R.

dont know about kaw 750 pistons
just talking about the 760 yamaha piston like the 85mm size

 

[Midlake Crisis]

Machinist says I am safe to bore to 81.5mm -
Do I buy full price 81.5mm ProX Pistons, or half price 82mm pistons and have him go bigger with the cylinder bore?

i.e. is it worth it so save $100 to go another 1/2 size over?

 

[DAG]

Machinist says I am safe to bore to 81.5mm -
Do I buy full price 81.5mm ProX Pistons, or half price 82mm pistons and have him go bigger with the cylinder bore?

i.e. is it worth it so save $100 to go another 1/2 size over?

82mm is the new bore standard. No reason at all for 81.5 when 82mm are so cheap. Hit up @Wizards Powersports for a deal on pistons

 

[Big Kahuna]

61X cylinders start to really come alive at 82mm even more so at 83mm

 

[CJSHAW636]

61X cylinders start to really come alive at 82mm even more so at 83mm

in a similar situation with my 61x right now, do you need to do anything else to run at 82mm? (Domes, ports, etc?) stock 61x with a coffmans system, project ski

 

[WFO Speedracer]

OEM piston to wall clearances are set up for a lengthy break in period and tend to be on the tight side, years ago when I started working on Seadoos their piston to wall was set up at .025-.030 the engines kept having seizure issues and our shop stayed very busy rebuilding top ends, customers were not happy to say the least, I looked at the clearances and said that's way too tight and I started setting them up at .004 , most of our top end seizure problem went away after that.

 

[Big Kahuna]

in a similar situation with my 61x right now, do you need to do anything else to run at 82mm? (Domes, ports, etc?) stock 61x with a coffmans system, project ski

Port job would really help!!!!!!!!! 83mm is actually even better, but you are technically at the last bore at that point...... (Not recommending overbore and running 84mm)

 

[CJSHAW636]

Port job would really help!!!!!!!!! 83mm is actually even better, but you are technically at the last bore at that point...... (Not recommending overbore and running 84mm)

Thanks for the help! I’d like to leave some meat on the sleeves in case I run into issues down the road.

 

[fastgtfairlane]

I'm curious how much better going to 83mm from just .5mm at a time is worth. When I had my 62t engine built, Paul recommended going to 83mm and said they really wake up at that bore. I decided to go with it luckily the 62t cylinder is thicker and I still have 2 bores left before needing sleeves.