Mods for 91 FLHTCU
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Joined: Dec 2013
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From: Dayton Tn
Mods for 91 FLHTCU
What would be some good mods for my 91 ultra? So far I got a k&n air filter and the rest of the bike is stock. I know I need a good set of pipes but will changing the head pipe make that much difference?I know I want to put a 21 on the front and lower the bike a bit..Some good engine mods is what iam really looking for..thanks in advance
Ultimate HDF Member
Joined: May 2006
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From: Ohio
Look, there are only three things to concentrate on:
1) Make it go.
2) Make it handle
3) Make it stop
Everything else is optional.
You've started to make it go. Remember to balance your mods. Since a motor is an air pump, free flow intake requires a freer flowing exhaust which requires re-jetting to rebalance the fuel needed.
To extend this further, replacing the factory cam will wake up your motor but only if you have done all of the above.
I'm not a fan of either 21" front wheels or lowering a bagger because it does not meet any of the three items I started with, but wtf, it's not my bike.
1) Make it go.
2) Make it handle
3) Make it stop
Everything else is optional.
You've started to make it go. Remember to balance your mods. Since a motor is an air pump, free flow intake requires a freer flowing exhaust which requires re-jetting to rebalance the fuel needed.
To extend this further, replacing the factory cam will wake up your motor but only if you have done all of the above.
I'm not a fan of either 21" front wheels or lowering a bagger because it does not meet any of the three items I started with, but wtf, it's not my bike.
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Joined: Jun 2007
Posts: 45,429
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From: Bedford UK
Team, you are mixing up two things here, one is wanting improved performance, the other is wanting to customise it. Now while I am not a traditionalist, I fail to see any merit in large narrow front wheels, which risk messing with both 2 and 3 in Beemer's list. You are also working with an old bike for which the parts that are available for recent models may not fit.
As for your questions, a change of head pipes isn't necessary, but decent mufflers will give a small improvement, as will a new ignition module. The reason for the latter is that the stock unit uses advance curves to keep EPA happy. Raised CR and ported heads all help, but IMHO don't try to mix and match yourself, call an established tuning shop for advice. They will be able to supply all you need and a set of components that will all work together.
As for your questions, a change of head pipes isn't necessary, but decent mufflers will give a small improvement, as will a new ignition module. The reason for the latter is that the stock unit uses advance curves to keep EPA happy. Raised CR and ported heads all help, but IMHO don't try to mix and match yourself, call an established tuning shop for advice. They will be able to supply all you need and a set of components that will all work together.
Stellar HDF Member
Joined: Oct 2005
Posts: 2,379
Likes: 226
For making affordable, proven mods to your evo, this is some good reading for you below... Depending on your budget, you can build a stage 1, stage 2 or stage 3 level motor from your stock Evo.
http://www.nightrider.com/biketech/hdbuildstage2.htm
http://www.nightrider.com/biketech/hdbuildstage2.htm
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From: Ohio
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Joined: Jan 2011
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From: Michigan 15 Minutes East Of Hell
The mufflers ( and exhaust pipes ) on your scooter are "flanged" if they haven't been upgraded. "Slip Fit" mufflers are not compatible. You'll need to use the head pipes of of a later model bike ... Hope this helps.