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Discussion Starter · #1 ·
I've got my 73 ironhead stripped all the way down for rings, gaskets, a new 2nd gear, and new needle-bearings. The rod bearings and such seem to be in pretty good shape, so i'll be leaving those alone for now. The side to side play is very minimal.

What things should I do while I'm inside the motor that will give me a smoother ride or a longer engine life? I'm not looking to hotrod, just mods that make good mechanical sense. Automatic timing chain tensioner? Beefier pawl carrier? Tamer Style Thrust Collar? Any ideas and a brief explanation of why they're a good idea would be greatly appreciated.
 

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Hydro clutch ....
 

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Get the crank dynamically balanced.

If the engine mounting bolts are not a nice snug fit in both the frame lugs and in the engine cases, that can also cause excessive vibration. The top bike builders ream/drill the cases and frame to accept slightly larger diameter bolts that fit snugly.

Think about lowering the compression slightly (thicker base gasket/head gasket) or, if you're buying new pistons, slightly lower compression pistons. The engine might put out slightly less power but it'll be easier to start and less vibratory.

Lowering the final gearing (one tooth bigger sprocket on the front, or two or three less teeth on the rear) will give you lower rpm at highway speeds, better gas mileage and less vibes.
 

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Discussion Starter · #4 ·
Matt - I've heard a hydro clutch is a good idea, but why? I'd prefer to have less fluids to leak, if possible. That's one of the reasons I'm going dual drum on this bike. KISS method.

Glider: plan on a smaller rear sprocket already, so good call on that one. One of the main things i'll be doing on this bike is commuting to work, so lower RPM's on the highway are good for two things, MPG and longevity. =)

Never thought about lowering the compression. I very well might do that. Where would I find intentionally thicker head-gaskets?

I need to find a shop that I trust in the Dallas area to balance my crank. I'm eternally suspicious of machineshops. If anyone has a recommendation, I'd love to hear it.

Not sure exactly what you mean about the motor mounts - unless you're saying to make the bolt holes larger than needed to allow a bit of wiggle room during install, in order to get a tighter fit and more even pressure on the mounts at the end of the day...? (no, you weren't confusing. I'm just a bit thick in the head at times. Haha)
 

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Extra thick head gaskets for lower comp, seen hem in jp cycles I think.

Hydro clutch to get rid of ball and ramp clutch set up.

Talk to dragstews for balancing. I am sending my entire bottom mend and cases out to him to send back done. He is in Florida.
 

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Discussion Starter · #6 ·
I'd thought about doing the same thing, mailing him my entire bottom end. I've seen some of his work on here, and read his responses to questions. I'll PM him and get some quotes.

Why is the hydro better than the ball-ramp? I'd considered doing a hydro clutch and doing a cable actuated hidden M/C. I don't like the handle-bar mounted reservoir. I'd kinda hoped to stay away from hydraulic brakes or clutches, just to avoid having another fluid to keep tabs on, but if it will stay running longer, I'm down.
 

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The ball and ramp setup will not stay adjusted for longer than a week at most. The hydro clutch will let you shift through easy and glide into neutral. If you want to keep the master cylinder off of the handlebars put a remote master on the frame with a cable pull to keep it out of sight.
 

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Discussion Starter · #9 ·
Matt: thanks. Sounds like hidden m/c hydro is going to be the plan.

Thrillphil, thanks! Have you used him yourself? I'll call him for quotes this week.
 

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Rockett, John John in Irving is also a good motor guy. To be honest, Kirk has not done any motor work for me, he does have a great reputation, around here, for being a very good mechanic! If you catch him around closing time, he might drink Coors Original, just a guess.
 

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Discussion Starter · #11 ·
Hmm. Maybe I need to drop in with a 6pack and shoot the shit for a while.

Anyone have any other ideas, as far as longevity mods?
 

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If it is apart apart replace the rod for s&s crankpin, pinion shaft, and gear shaft with new stuff from s&s or Jim's.
 

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Yeah bearings without a question. Look at us adding a grand to your motor
 

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Block off the oil transfer valve also. Its between the crankcase and the primary and is known to allow the oil from your crank area to flow into the primary area.
 

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Discussion Starter · #18 · (Edited)
Thank you guys for all the responses.

Excellent points, good sirs. You're most correct, re-using bearings would be foolhardy. After some research and talking to dragstews, I'll probably replace the rods. Still making my list, at the moment.

I've taken apart several sporty motors and replaced broken things, but I am definately not experienced, and not a machinist. I just take them apart, and replace things that look broken. This time, I want to build a motor the RIGHT way.

Ideas:

rods
extra thick head gaskets
balance crank
-2 or -3 rear sprocket
Automatic timing chain tensioner
Tamer Style Thrust Collar
needle bearings
hydro clutch
crank pin
gear shaft

Missing anything? This motor is getting expensive. I've been saving, though. I don't want to be back inside this motor in the next ten years, so it's worth it. Plus, I won't ride it like i ride my CB. This is going to be my gentle bike.
 

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Take a look at the oil passages and the interior of the case. Smoothing the transfers of casting flash and whatnot. Especially the area that scrapes the crank, and transfers back to the cam chest. I heard you can polish the inside of the case for a little extra from friction losses.

The heads dont need to be ported cause the ports are huge anyway but they have some smoothing that can be done especially the inside corner below the valve seat. while pretty unscientific, use compressed air at around 30 psi or less to blow through the ports, you can feel the flow layers with your fingers to give you a good idea on how smoothing the casting flash helps.

look at all the gasket surfaces and use a file to make them flat again, such as the two case halves.

check for locating dowels and redo the ones that are missing, chances are there are some that are gone.

look at all the internal threads and clean up the ones that are not so pretty.

check your rockers for a mixed order. the exhaust rockers have an extra oil passage that puts some oil on the valve for a little more cooling. these are often mixed and not right (mine were).

this is stuff you can do on your own and doesnt cost much, but helps you see all corners of the motor.
 
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