Big Bore Ironheads
 

In the post a pic forum there's a few with comments about their engines being bored out from 74-88" where can I find some more information about this? if it doesn't cost an outragous amount I might think about ripping the motor apart and put out some more ponies:) and I don't really care about rideablilty or reliability that much anymore. theres other HD's around the house to ride.

RE: Big Bore Ironheads
 

I thought guys learned decades ago that big bores and Ironheads don't exactly go hand in hand. The cases are weak compared to the EVO's. A set 30+ years old ain't gotten any stronger. Sure, people have done it with success and I'm sure someone will chime in and tells us so, but many have also blown the bottom end out of a Ironhead. I think I'll stick to my stock bike and ride it another few decades.:D

RE: Big Bore Ironheads
 

Here is some performance talk from ironhead http://autos.groups.yahoo.com/group/...adperformance/
There is 0.07" pistons avaleable but it isn't recommeted to bore stock cylinders over 0.04" and that's not yes big bore !!

RE: Big Bore Ironheads
 

I had seen some custom made 3.5 inch cylinders on ebay a while back. 1200cc Ironhead on a stock stroke would be awesome.

RE: Big Bore Ironheads
 

I had a 77" stroker, but the bore was just an .020 cleanup job. You wanna play with torque, get stroked. You really can't bore stock cylinders enough to notice any performance increase. Need to go with special jugs, and all the machine work on the cases to make 'em fit, and that weakens the cases even more.

And if you start playing with Sporty power, you'd better get a heavy duty trapdoor for the tranny. Actually, you will get the heavy duty trapdoor, it's just a matter of getting it before or after you blow the old one to smithereens! Plus sooner or later you'll miss a shift and blow the lower right rear corner of the tranny section of the cases. But they make repair kits for there, too!

I knew one dude, a very serious squirrel, who had a 118" Sporty Ironhead. It was one wild motor, but really not for the street.

RE: Big Bore Ironheads
 

You need think really hard if you are using steel trapdoor, it's much easier to replace trapdoor than repair cases :eek:
Atleast if you are using steel trapdoor support bearing in front spocket is good idea...

-sepixlh-

RE: Big Bore Ironheads
 

wasn't steel, just beefier aluminum design. Trapdoor, and sometimes replacing the lower right rear corner of the case, was done as part of the build.