300/440/550 Newbie intro

[Iniquite]

Hey, I just registered here because PWCToday cant get their $hit straight. I figured I'd introduce myself and my ski. I spent about a year slowly building my PJS ski centered with T3 cylinders I scored in a pair of skis I bought for $250. I got PJS duel carb intake, PJS full exhaust and mani, PJS exit and turn nozzle and PJS ride plate. I sent the cylinders to Robert Sand to bore them and get new wiseco pistons windowed. After a big ordeal with him I got them back but wasnt too happy with the pistons. The holes where not done right and he got single ring pistons. I built the PJS cylinders on a 440 trued and welded crank and a PJS head on top with about 185 in both holes. I got the motor together over the winter and got it fired up. Sounded great and was eager to get it on the water.

The big day finally came yesterday. I got wet and it was running great, tons of power. Then, about ten minutes in to the ride, I lost a cylinder. Once I got it home I pulled the head and found out what happened. It looks like the ring was catching on a port and caused pieces to get in to the chamber. Head and piston are trash and I get to start my build over again right at the beginning of summer. Ill be doing all the machining myself this time.

 

[Matt_E]

Nice ski. Sorry about the topend, it's the worst time of the year.

 

[cookn]

Im guessing the ports were not chamfered enough causing the ring snag. Maybe the bore was a little tight for the forged wisecos. now you can get the correct double ring pistons. I have also heard of people running the pjs cylinder without the boost ports cut in the pistons.

 

[Iniquite]

The windows are just to get airflow under the piston and help cool it off. It helps prolong the life of the piston. I could run it with out them and not hinder any performance but I might as well put them in. Yea your right there where two ports that didnt get chamfered at all. I could contact Robert Sand but I already know he wont do anything about it.

 

[Matt_E]

The windows are just to get airflow under the piston and help cool it off. It helps prolong the life of the piston. I could run it with out them and not hinder any performance but I might as well put them in. Yea your right there where two ports that didnt get chamfered at all. I could contact Robert Sand but I already know he wont do anything about it.

In piston port motors, those holes have a function other than just cooling.

 

[cookn]

It is not a piston port. The so called windows that PJS cut in the pistons for these reeds cylinders, i believe were to boost the charge going to the crank case, this seems to be the general idea on what i have read at least. I have also seen the windows cut in a bunch of different configurations. In stock pistons there are usually small just under the rings to help oil the rod bearing. I had a piston port running reed motor pro-X pistons and they didn't have any holes and it ran for years. I think its all what makes you feel good when you build up the motor.

 

[Ĥölënböt]

wiescos are trash use wsm or pro x next time

 

[Matt_E]

Is that a general statement or applicable only to 550's? :thinking:

 

[Iniquite]

I personally prefer forged over cast but I have not run pro x or WSM. Wiseco has never let me down.

 

[cookn]

Agreed there is nothing wrong with wiseco. WSM is bottom line. If you have had a bad experience with forged pistons in your 550 then your machinist is probably to blame.