I have a 2006 Ultra Classic with a trike kit on it so it's a heavy girl. I have a spare set of jugs from a 96 and was thinking about boring them out. Initially was looking at going to 95 inches but of course got thinking about going bigger. So, the question is considering this is a trike, what is the largest I can safely bore out these cylinders? Also, any suggestions for pistons?

 

The debate of not having a timken bearing on the crank comes up. 95" non epa is nice. Can't say for trike

The jugs on 96" are the same size as your 88 jugs. To get to 96 they stroked. For you to get over 95/98 you need to stroke. If you are going to remove the engine I would consider timken conversion.

 

The timken, or lack of it, is not the issue with the cranks. Never was.

 

Around 2004 or 2005 they did change cranks. But many felt removing the timken in 2003 was not good.

Either way those jugs won't work for him.

 

Do the 95" kit with a bump in compression ported heads and a good torque cam,that will really wake it up a lot.
A 103" stroker kit would be nice but that gets way more expensive.

 

The 95" is the most economical low buck way to get bigger horsepower. (I had one for 172,000 miles (203 cam) and it was reliable.)

If money isn't an issue, a 98" option with worked heads from a builder (Hillside?) would get you even more (but at greater cost of course.)

I wouldn't mess with a properly aligned ( < .003") 2006 crank.

 

Oh, it was with 2003 cranks. Number have blown up when you pumped the motor up.. HD did update the bearing and changed the torque procedure on the comp nut.. 06 should be OK tho..

 

The comp nuts are different in my 5 speed and 6. But the manual printed in those eras, I think have very similar tq practice. I beleive both just have a value to tq to. As opposed to marking and going another 90 degrees or whatever they have now.

 

OP, call Scott at Hillside, he'll get you set up with exactly what you want with no BS and at reasonable expense. Great guy to talk with. You can send him those jugs and your heads and he'll fix them up right.

 

98" is the limit unless the crank is changed and once you pull the motor for a stroker kit there are many options for a variety of larger displacment motors which is a simple function of how much money the OP has/wants to spend.

It is possible to build a pretty strong 98" motor (I would not stop at 95") but it takes planning and parts the play well together. I built a 98" motor year before last shooting for 120/120 numbers but missed the mark; had to settle for 115/115. Not saying 120/120 is not possible but if the OP wants more than 115/115 a crank is in his future.

I don't know what the gearing is in the trikes but in addition to increasing displacement, perhaps a gearing change might be worth looking at.