Wiseco pistons

[bonitoman]

Re: Wiseco pistons

NGK plugs were in the engine. They looked good, even the bad cyl.

 

[Dhadley]

Re: Wiseco pistons

Very typical. <br /><br />The #3 is the hottest cylinder on that motor, especially if someone got a bit crazy with the RVT when they rebuilt it the first time. You may not find anything other than it had the wrong plugs. <br /><br />Good info!

 

[bonitoman]

Re: Wiseco pistons

What plugs would you suggest to be in that 60 degree and what is RTV? Are you referring to the gasket material around the head?

 

[Dhadley]

Re: Wiseco pistons

The book calls for Champion QL78YC's. I run QL77JC4's in all mine. I like the "tad cooler" heat range. Yes, the RVT is the stuff on the cylinder O rings and around the water passages. I wouldn't use silicone. Ya gotta be careful around the passages that flow from the block to the head. Too much and it will squeeze out and possibly hinder the water flow.

 

[bonitoman]

Re: Wiseco pistons

What exactly do you use on the oring and on the head? I thought triple guard grease on orings and red rtv around the head.

 

[Dhadley]

Re: Wiseco pistons

We've seen it done that way and it seems to be OK. The big thing it not to plug (or partially plug) those main water passages.

 

[bonitoman]

Re: Wiseco pistons

Dhadley, What do you use on the head and o rings to seal everything? Do you get it from OMC?

 

[dixie420]

Re: Wiseco pistons

so your gonna bore one cylinder .040 over standard, and leave the other three .030? i can see alot of reasons this is a bad idea. most importantly the size difference will cause the engine to be out of balance. you cant expect to keep bearing in a motor like this. and no, doing one cylinder on the other side will not work. plus the heat is a big factor, that cylinder will be hotter than the rest, pull more fuel, expel more exaust and throw off the harmony of a fine tuned motor. if you were my mechanic i would fire you.

 

[BRIAN03]

Re: Wiseco pistons

Balance is not the problem. The aftermarket pistons take that into consideration. We will only bore an engine square (all the same). I dont think he's looking for a job either. If we can't get them all the same bore. We sleeve the one that will bring it to the other bores. If you want to bore one only. We say take it to some else.

 

[rodbolt]

Re: Wiseco pistons

hello<br /> dude I normally desire to replace all the pistons with the same size not due to any minor balance or displacement differences but due to piston skirt to cyl wall clearence. that said my poor 120 VRO has .030 on number 3 due to my buddy forgot to loctite a reed screw back in dec of 95. I put a .030 omc piston in it then and bought the rig in 99 and it runs 4800-5200 anywhere I go. I either idle or run and have since 99. so the balance issue is a dead one.<br /> the first guy that replaced the power head sometime in the mid ninties did not check the reeds very well but in 95 the pistons and cylinder walls looked great with exception of number 3. a screw is a terrible thing to lose . but you are correct in you must ID the piston manufaturer. wiesco pistons require a different bore than factory pistons. if the machinist is not aware that you are going to use wiesco pistons it will fail. a factory bore size or any multiple of oversize wont work for wiesco pistons. <br /> good luck and keep posting

 

[Dhadley]

Re: Wiseco pistons

All 31 series Wisecos use the factory spec for boring.