Thinking of building my engine this winter....

[Hdale85]

So I was curious, what's the biggest bore you can run without sleeving? Will the jug take an 85mm piston? Or is that likely just taking it too far?

Also will a +7mm crank work fine without doing anything?

Maybe I'm stupid here.....but trying to see if I can get it up to 400cc's without any major modifications like sleeving the case/jug.

 

[duneracerweston]

it can take a 85mm without boreing but thats really far imo to punch one out thats .080 over but alot of guys run the 85mm 366 big bore

and for the +7 crank i think its a drop in but you have to run special pistons at .040 over to do that but i may be wrong

 

[DeadLastRacing]

yeah. .80 bore is an 85mm piston. Biggest yo can go on stock sidewalls.

if you stroke it that much, you have to mod the case. I think +4 is as long as you can go with a non case mod.

 

[duneracerweston]

and that with .040 over puts you close to 379cc if i remember right

 

[Hdale85]

So probably looking more at like 380cc's without case modification?

Does someone make an 84.5mm piston? With that and a +4 that would be 384cc's. Just figuring if I'm going to bore and what not I might as well go as far as I can without killing too much reliability. I could probably afford to do a 420,430,446 but I'm not sure I want to risk it that far.

 

[Hdale85]

Also I think getting up above 400cc's might be stepping into the diminishing returns area.

 

[elwood]

you can use the hot rods +7mm stroker without case mod but they don't make it anymore so ebay and if you break it no replacement from hotrods. You are supposed to run their stroker piston that is an 84mm with it. Another option on pistons is get ahold of JE and talk to them about making you a custom one if you want a bigger bore. There is a thread in here somewhere that talks about all of this, I called hotrods and the tech guy didn't know they even ever had a +7mm I argued with him and he found it but it was last in production back in the 90's I think

 

[Hdale85]

There are a few places that will modify your stock crank I know, but yeah I found a few places that have +7mm cranks but I don't think they are hot rods?

So Hot Rods has an 84mm piston that'll work with the +7mm crank and not require sleeving? That's ALMOST 400cc's, 396CC's.

 

[elwood]

yep here is the crank http://cgi.ebay.com/ebaymotors/YAMA...189133QQptZMotorsQ5fATVQ5fPartsQ5fAccessories
and here is the piston http://cgi.ebay.com/ebaymotors/YAMA...937247QQptZMotorsQ5fATVQ5fPartsQ5fAccessories

 

[Hdale85]

200 for a piston? That's a bit much...I think I contacted this guy once and he'd do the kit together for like 400 something.

 

[elwood]

let us know if you find it cheaper

 

[Hdale85]

I think it was the same guy on ebay that sells the crank and piston separately.

Ok I looked through my emails and it was this ATVUnlimited guy, he said 520 delivered. Most pistons are 100-150 though for the nicer JE, Wiesco and so on. That's why I said 200 seems a bit much for a piston.