Ive got a 1978 Ironhead that id like to build up a bit with my father, its a 1000cc and i was wondering what my options are with it, id also like to know if i could bore it out to make it a 1200 or if id be better off doing a motor swap, i honestly dont even know if thats possible, as you can probably already tell i dont know a lot mechanically about motorcycles, im a mechanic but for things that use 4 or more wheels, id appreciate any input and advice, thank you

 

No performance advantage can be obtained by over-boring the cylinders; that process is used only for rebuilding a worn engine. It can be over-bored .010", .020", ..., .070" then new cylinders are needed.

More power can be obtained by stroking, but it is an expensive process and usually reduces engine life. For a street bike it is best to stay with the stock engine size.

Consider high performance, high compression pistons, hot cams, head work, etc. I am not expert on these topics.

You might find this book published in 1984 ...

V-Twin Thunder!
A Handbook of Performance Modifications for Harley Davidson Motorcycles
Carl McClanahan, Mike Arman

It is out of print, will never be produced again, may be found from time to time on eBay, Abebooks, etc. Be prepared to spend way over $100 for a copy.

 

thank you, i appreciate the advice

 

I did a rebuild on my 1975 sportster,pistons .030 over,just for rebuild perposes , i also filed my intake ports out,from the factory they were very rough,so get them smooth,and this will help with getting more air in.You will not feel much difference with a 1000 to 1200,but in the cost to change your motor will be lots of $$.

 

Also, if anyone knows, did these bikes come stock with a 4 speed?

 

Transmission is essentially the same from 1957 to about 1990 - 4 speed. There is no reasonable possibility of a 5th gear.

 

Post some pics of that bad boy as you go