heads and cylinders off...
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Intermediate
Joined: Aug 2006
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heads and cylinders off...
My rocker boxes were beginning to leak quite a bit of oil, so yesterday I pulled them (along with the heads) off of the motor. After I did, the tops of the cylinders seemed to have a pretty good lip and so I figure that I'll have them checked while the motor is apart.
My questions is: what are my options for upping the performance of the motor a bit at this point? Does anyone make aftermarket cylinders that significantly increase the displacement?
Also, what sort of things should I check while it's apart?
It's a '73 Ironhead that I bought about a year ago. It runs well, overall. Here are photos of the front and rear pistons. How do these look?
thanks,
Chris
My questions is: what are my options for upping the performance of the motor a bit at this point? Does anyone make aftermarket cylinders that significantly increase the displacement?
Also, what sort of things should I check while it's apart?
It's a '73 Ironhead that I bought about a year ago. It runs well, overall. Here are photos of the front and rear pistons. How do these look?
thanks,
Chris
Road Warrior
Joined: Nov 2006
Posts: 1,441
Likes: 791
From: Heart of Dixie
RE: heads and cylinders off...
The pistons look pretty good to me. There aren't many (if any) big bore cylinder/piston kits available for ironheads any more. You can go with a bigoverbore and high compression pistons and dual-plugged heads (practically a necessity with high compression pistons), and a good valve job, but you start to get into a money pit the more you do.
Stellar HDF Member
Joined: Feb 2006
Posts: 3,035
Likes: 17
From: Houston Texas
RE: heads and cylinders off...
ChrisB....
When you look at pistons what you want to look at are the skirts, not so much the piston tops. The skirts are what get galled and scratched, especially if there is an issue from a shortage of lubrication or broken piston rings.
From the small detail I can view of the skirts, they look pretty good, but you are the one who can look at them closely and I urge you to do so.
In my opinion I would try to discourage you from trying to increase the displacement of the Sporty. There are some big bore cylinder kits out there but if you buy a kit then the crankcases have to come apart and there is considerable machine work to be done so that these replacement cylinders can fit down into the hole in the cases. This kind of thing starts to eat money at the speed of light. Jay Leno can do it but most of mere mortals should pass on this exercise.
I would bore out the cylinders just enough to clean up the walls and no more. By keeping the boring increase to a minimum you have bought yourself more rebuilds later down the line.
You can bore it out to .070 oversize and you will not realize any more power increase, but you have wasted the cylinders because they have no more life left in them. Bad idea................pg
When you look at pistons what you want to look at are the skirts, not so much the piston tops. The skirts are what get galled and scratched, especially if there is an issue from a shortage of lubrication or broken piston rings.
From the small detail I can view of the skirts, they look pretty good, but you are the one who can look at them closely and I urge you to do so.
In my opinion I would try to discourage you from trying to increase the displacement of the Sporty. There are some big bore cylinder kits out there but if you buy a kit then the crankcases have to come apart and there is considerable machine work to be done so that these replacement cylinders can fit down into the hole in the cases. This kind of thing starts to eat money at the speed of light. Jay Leno can do it but most of mere mortals should pass on this exercise.
I would bore out the cylinders just enough to clean up the walls and no more. By keeping the boring increase to a minimum you have bought yourself more rebuilds later down the line.
You can bore it out to .070 oversize and you will not realize any more power increase, but you have wasted the cylinders because they have no more life left in them. Bad idea................pg
Cruiser
Joined: May 2007
Posts: 149
Likes: 2
RE: heads and cylinders off...
I'm with Pinion Gear on this. If you want a little more performance, update to a Keihin carb and p cams and buy a good set of pipes. A set of progressive springs in the frontend will also help more than you might expect. I've turned mid-thirteens on a well-tuned stock bike, and for the first eighth mile or so even present-day performance bikes aren't that much faster than a good running Sporty. Maybe I'm just old, but how much faster do you really want to go?
Road Master
Joined: Aug 2006
Posts: 751
Likes: 6
From: 500 miles south from Artic Circle
RE: heads and cylinders off...
PG is right no bore if isn't absolutely needed, most of IH performance comes from cylinderheads
you might want to look what Tom Gordon has on his mind, give him a call.
you might want to look what Tom Gordon has on his mind, give him a call.
Thread Starter
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Intermediate
Joined: Aug 2006
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RE: heads and cylinders off...
Thanks for all of the replies everyone. I'm going to leave well enough alone for now and just have a little work done on the heads- replace the valve guide seals and get a valve job.
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