Whats the max bore & stroke you can get out of the points atc 90 motors?

[Shorty]

What the title says. I'm pretty sure its 61x61??

[shortline10]

I have a 61.5 stroker but 61mm on the cylinder is max unless you plan on moving the head studds out .

[Shorty]

I have a 61.5 stroker but 61mm on the cylinder is max unless you plan on moving the head studds out .

Ok but where can you find a jug & head for the spaced out head studs?

[shortline10]

Ok but where can you find a jug & head for the spaced out head studs?

All custom fab stuff .

[Vealmonkey]

Well, really the jug and head aren't custom fabbed, they are just taken from other machines. The fab work is really in the cases and the internals of the engine. And there is alot more to a big bore 90 engine than just 61x61. It depends on wether or not you have a stroker rod or you are using a stock length rod and a stroker plate and all kinds of stuff like that. The planning and building and assembling of a racing big bore 90 is quite extensive really. And you have to know if you are burning high ocatane gas or running alcohol. There is the blueprinting of the internals which can be a time consuming task. There are all kinds of tricks, too numerous to mention in a paragraph. The actual time and costs to build a race worthy 90 engine are pretty staggering. If you know alot of the tricks and are doing the work yourself, then of course the costs are substantially less, just mainly your time and labor, but to pay someone to do that kind of work, let alone finding someone willing to do it or who remembers all the tricks, well, best of luck with that. Let alone finding all the parts to even do such a build nowadays is really tough. Some of us have been either sitting on parts for awhile or are beating the bushes to find the real hard to find parts to do such a thing. These parts haven't been made in years. And powroll doesn't stroke the cranks out as much as they once did since now these parts are over 20 years old and may not have the life expectancy they once had. How many people on here go to the trouble of balancing a piston and connecting rod assembly for a atc90? And that is but one of many things that you should do to even begin to build a real performance big bore 90. And once you spend alot of money on hard to find parts and assembling everything with more love and care than most honda 90s have seen in along time, who's to say the engine won't come apart on you in 15 minutes? Well, if you did everything right it shouldn't, but it does happen, even to the best. It's really a whole lot more than just putting a stroker crank and big bore piston in a 90 engine and slapping it together overnight, trust me on this one. It's not for the impatient, faint hearted or for the shallow pocketed, that's for sure.

[Vealmonkey]

And I almost forgot, you can go bigger than 61x61. Like upwards of 200ccs!