help me choose a piston

[1998yamahawarrior]

By luck I have got the money quicker than I thought for a replacement piston. Well to keep everything as is setup wise requires racing fuel, which I can get at multiple places around me. Well now since that I want a little input from our great members. Do you guys think I should stock with the 10.5:1 JE or go to the 12:1?

 

[Gen1Pat]

I say go with the 10.5:1. It's still going to have a good hit, you can run pump gas, which means that it is going to be easier to fuel up when you are away from home. It also means that you can run your Dyantech with less worry that it will detonate again because of ignition timing. Also, you can use a thinner base gasket to get the comp closer to 11:1. You had said earlier that the head was decked .015". That being said, I'd stick to the "smaller" piston.

 

[YAMAHAULER]

I agree with Pat just makes a lot more sense

 

[lbjamm]

X2 with what Pat said. You can fuel up almost anywhere.

 

[duneracerweston]

Don't even ask my opinion... :evil:

 

[1998yamahawarrior]

Let me guess Weston your the lone 12:1 vote!!

 

[frit91]

My $0.02, I would go with the lower comp because there is no where around where I live to get racing fuel. But if I had easy access to it like you do it would make it a tough decision. As far as being easier to run pump gas when you leave to go on a ride somewhere else where race fuel may not be readily available, just fill some cans at home before you leave and you have no refueling issue. That being said I would still probably go with the 10.5 to 1 piston as it has been my experience that the lower compression is just overall easier on components. I am just glad to hear Jar-Jar isn't going to be on the shelf for very long.

 

[Gen1Pat]

My $0.02, I would go with the lower comp because there is no where around where I live to get racing fuel. But if I had easy access to it like you do it would make it a tough decision. As far as being easier to run pump gas when you leave to go on a ride somewhere else where race fuel may not be readily available, just fill some cans at home before you leave and you have no refueling issue. That being said I would still probably go with the 10.5 to 1 piston as it has been my experience that the lower compression is just overall easier on components. I am just glad to hear Jar-Jar isn't going to be on the shelf for very long.

I've thought about doing that myself, but, what happens if you run through all of your fuel supply? I'll just stick to pump gas. You can still have a dynamite engine without pushing max compression. Like I said above, 11:1 seems to work perfect for me.

 

[1998yamahawarrior]

Well if Westons calculations were correct Im already at or a little above 11:1 with the piston and shave running the 10.5:1 piston. Anyone have access or know what a stock warrior head should measure before any surfacing? I havent come across a spec for it yet.

As for planning with race gas for trips, when we go up north the farthest trip Id still have roughly a quarter of a tank left. I do have a thought to run race gas even with the lower compression for safety, but make it still doable for pump gas. I really like the added umph the setting 3 on the dynatek gives!!

When I order the parts for putting it back together Im gonna add in Im thinking a 15 tooth front sprocket, possibly a 14 tooth just so I have a choice depending on what Im doing. A 15 would be great up north so Im not wound out keeping up on the straight streches. a 14 would be good for messing around and then I would still have the 13 tooth to for showing off!!! LOL

 

[Gen1Pat]

Your recent piston failure must have been from the Dynatech. I'm running the 11:1 Wiseco, with a little shaved off the head, and am having no issues. I am using a stock cdi though. And, on my Honda, I've got 11:1 big bore with a 400ex dynatech and it runs well on 93.

 

[1998yamahawarrior]

You wouldnt happen to know what the thickness of a stock head and the proper measurement point are would you Pat? If I do decide to just go with the 10.5:1, I wanna make sure there isnt more than the .015 shaved. If there is that could be another explanation to the detonation as Weston calculated with just the .015 off and that put me a little over 11:1, but we also figured the megacycle 252x1 would bleed some of that down a bit too. I just wanna get all my ducks in a row no matter what direction I go. The 12:1 being easiest because I mainly other than making sure clearances is just adding race gas. At either point Ill probably be turning down the dynatek till I know where I stand with either choice.

I really dont want to have to spend money on a 3rd piston!!!! LOL

And I have until Friday to decide, thats when I get the money that fell into my lap because of someone that has more money than brains!!!

 

[Gen1Pat]

No I don't know what the factory deck is on the head. If .015" was taken off, you can get a base gasket, or head gasket, made with and extra .015" thickness.

 

[1998yamahawarrior]

Well Ive decided to go with the 10.5:1 piston agian. I plan on getting another Cometic EST head gasket, since it held together so well with what was going on in the cylinder!! Now on the seach for one I find Summit carries them now. They list a few different thickness's. Im gonna try to remember to grab my old one and measure it at work. Im planning to get the thickest one they show which is .027". Im actually hoping that I measure the old one and its the other thickness listed at .010. If it is the thicker one would put me back to where it was before being shaved. Heres a link to summits search for head gaskets:
http://www.summitracing.com/search/...ype/powersports-head-gaskets/bore-mm/85-000mm

 

[1998yamahawarrior]

Piston is ordered, now to find someone that can get me the head gasket before July and without charging $17 dollars shipping. Cometic is the high shipping and eBay and summit are the over 2 week wait. Anyone know if some one has them actually in stock so I could get one next week.