GP1200R new piston destroyed - PWC Forum: The best hang-out for Personal WaterCraft enthusiasts
LinkBack Thread Tools Display Modes
post #1 of 2 (permalink) Old 06-23-2009, 09:41 PM Thread Starter
Junior Member
Join Date: Jun 2009
Posts: 1
GP1200R new piston destroyed

I have noticed quite a few posts on gp1200r eating pistons. What causes this. I have a ski with a little over 100 hours on it and it sounded like some piston slap in the motor. So I pulled it down and checked the cylinders which seemed ok but the pistons were worn. I put in three new pistons and first time out the center piston is destroyed, hole burned through the exhaust side and top of piston next to exhaust port looks burned. I used all new gaskets and the other two pistons look ok. I guess I will have to get the center cylinder sleeved. Should I do them all or can some tell me what usually causes this.
o2tech is offline  
Sponsored Links
post #2 of 2 (permalink) Old 06-24-2009, 09:15 AM
Senior Member
Join Date: Jun 2009
Location: Australia
Posts: 323
The 1200P/V motor runs about 2-4thou clearance. I have tried that many pistons in stock skis and nothing compares to the genuine Yamaha pistons and barrels. If you have your barrel re-nickalsiled you may have a problem. The nickasil just seems to peel off on the exhaust side no matter how rich you run it. OEM is expensive but they come with a size matched piston and WORK. If you are running OEM and it is failing check the power valve adjustment and carb settings. The fact that you have recently replaced the pistons to me means you may have installed the rings upside down? And don't get re-sleeved barrels for those motors, I can tell you a hundred reasons but they just don't work! Trust me, I have done hundreds of those motors!
GCwaverunner is offline  
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the PWC Forum: The best hang-out for Personal WaterCraft enthusiasts forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome